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Publications

SPECIFICATIONS AND TOLERANCES

FOR

COMMERCIAL WEIGHING AND

MEASURING DEVICES

HANDBOOK OF THE

NATIONAL BUREAU OF STANDARDS

M85

1929



DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

George K. Burgess, Director HANDBOOK OF THE NATIONAL BUREAU OF STANDARDS, M85

SPECIFICATIONS AND TOLERANCES

FOR

COMMERCIAL WEIGHING AND

MEASURING DEVICES

Miscellaneous Series, M85

(Superseding Handbook No* 1)

January, 1929

PRICE 50 CENTS

Sold only by the Superintendent of Documents, U. S. Government Printing Office Washington, D. C. UNITED STATES

GOVERNMENT PRINTING OFFICE

WASHINGTON

1929
ndarda

'i Ay F-i t fir 1 5"

-h U 3
CONTENTS

Page

Preface - v

Part I.—GENERAL

Judging the suitability of use of commercial weighing and measr* uring equipment 1 Part H.—SPECIFICATIONS AND TOLERANCES FOR COMMERCIAL WEIGHTS AND MEASURES AND WEIGHING AND MEASURING DEVICES, AS ADOPTED BY THE NATIONAL CONFERENCE ON WEIGHTS AND MEASURES AND RECOMMENDED

BY THE NATIONAL BUREAU OF STANDARDS FOR ADOPTION

BY THE SEVERAL STATES

Introduction 18

Specifications and tolerances 23

Linear measures 23

Fabric-measuring devices 25

Taximeters 30

Liquid capacity measures 37

Glass graduates 39

Milk bottles 44

Lubricating-oil bottles 46

Liquid-measuring devices 48

Grease-measuring devices 63

Vehicle tanks 68

Dry capacity measures 72

Berry baskets or boxes 75

Scales 76

Platform scales 82

Large-capacity automatic-indicating scales „ 90

Wheel-load weighers 92

Counter scales 92

Suspension scales of the lever type 98

Spring scales 98

Straight-face spring scales 102

Computing scales 104

Cream-test and butterfat-test scales 108

Prescription scales and balances 110

Weights _ 116

in
IV CONTENTS

Part III.—CITATION TO CERTAIN CODES OF SPECIFICATIONS

AND TOLERANCES FOR COMMERCIAL WEIGHING AND MEASURING DEVICES, OTHER THAN THOSE ADOPTED BY THE

NATIONAL CONFERENCE ON WEIGHTS AND MEASURES

Page

Introduction 1 20

General specification for scales 121

Railroad track scales 121

Two-section, knife-edge railroad track scales „ 123

Hand-operated grain-hopper scales. 124

Automatic hopper, hand-operated hopper, and railroad track

scales used for weighing bulk grain 124

Motor-truck, built-in, self-contained, and portable scales for railroad service 125

Wagon and motor-truck scales 126

Moisture-test scales 126

Liquid-measuring devices „ - 126

Electricity meters ^ . 127

Gas meters . 128

Water meters __..„- 128

Leather-measuring devices „ 129

Clinical thermometers— - 129
PREFACE

This volume is the second of the series of three handbooks

which are designed to replace that earlier publication of the

National Bureau of Standards known as Handbook No. 1, Manual of Inspection and Information for Weights and

Measures Officials. The first volume of the series has already

been published as Handbook No. 11, Weights and Measures

Administration; the third volume, which is planned under the

title Weights and Measures Technology, will probably be

published in about a year from the date of the present

volume.

The principal object of the present handbook is to present

in form convenient for handling and reference the specifications and tolerances recommended by the National Bureau

of Standards for those classes of commercial weighing and

measuring devices which are customarily examined by State

and local weights and measures officials. This group of

specifications and tolerances corresponds to the several codes

adopted by the National Conference on Weights and Measures. This material comprises Part II of this publication.

There are, however, some classes of commercial weighing

and measuring devices which, although properly coming

within the scope of the authority of the weights and measures

officer, are, by reason of lack of suitable equipment or suffi- cient personnel, regularly examined by only a few such

officers. Specifications and tolerances for some of these

classes of equipment have not been considered by the National

Conference on Weights and Measures and are, moreover,

not of primary interest to the weights and measures officials of the United States as a whole, Nevertheless a handbook

v
VI PREFACE

on specifications would be incomplete if published specifications and tolerances of this character were to be ignored,

and, accordingly, in this volume there is given a very brief

description of the scope of the more important of the existing

codes affecting apparatus of the character in question which

have come to our attention, together with references to sources from which the complete texts of such codes may be

secured. The person who may be interested in such codes

is therefore informed where he may secure the specifications

and tolerances which are not given in full herein. This

material comprises Part III of this publication.

Finally, there is a subject closely related to specifications

and tolerances upon which it is considered appropriate that

some comment be offered at this time. This is concerned

with the general considerations underlying the selection and

approval of devices for various commercial uses; in other

words, with the efficiency of utilization of equipment. It

is the purpose of this discussion to emphasize the importance

of the subject and especially to develop its relations to the

specifications and tolerances which are presented herein.

This discussion, prepared by F. S. Holbrook, of the Bureau

of Standards, is entitled "Judging the suitability of use of

commercial weighing and measuring equipment/' and it comprises Part I of this volume.

While primarily prepared for the information of the State

and local weights and measures officials of the United States

and manufacturers of commercial weighing and measuring

devices, it is believed that interest in the material presented

in this handbook will by no means be confined to these

groups, but that it will be of much assistance to other interests as well. The codes contained herein form the basis for the

State and local regulations governing such devices in practically all parts of the country and in very many cases are
PREFACE VII

identical with such regulations. Industrial and manufacturing concerns and purchasers in general will thus find set forth standards for materials, design, construction, and performance which have been carefully worked out over a

period of years and have received general indorsement.

They maj^, therefore, safely be accepted as criteria for the purchase and maintenance requirements for the noncommercial

as well as the commercial weighing and measuring equipment

of such concerns. Finally, every purchaser of weighing or measuring equipment may find the discussion on the selection and utilization of such equipment of some assistance in

choosing the devices best adapted to his particular needs.

SPECIFICATIONS AND TOLERANCES FOR COMMERCIAL WEIGHING AND MEASURING DEVICES

Part L—GENERAL

JUDGING THE SUITABILITY OF USE OF COMMERCIAL WEIGHING AND MEASURING EQUIPMENT

By F. S. Holbrook,

Principal Scientist, National Bureau of Standards, and Secretary, National Conference on Weights and Measures

The contents of this volume will be found to be largely

concerned with recommended specifications and tolerances

with which it is believed that commercial weighing and measuring apparatus of various classes should comply. Experience in the enforcement of weights and measures laws has

amply demonstrated the necessity of the application of such

specifications and tolerances as are herein contained and

there can be no question of the wisdom of purchasing commercial apparatus in compliance therewith.

It is to be recognized, however, that the whole problem

of the procurement of satisfactory apparatus in various commercial uses will not necessarily have been solved, even after

satisfactory codes of specifications and tolerances for commercial apparatus have been promulgated and are enforced

in a given jurisdiction, valuable and necessary as this procedure may be. The painstaking official is sure to find that

ideal conditions are not to be attained by these steps alone

that along with the above other precautions are to be ob1
2 NATIONAL BUREAU OF STANDARDS

served. One of these may be stated as the securing of a proper relation between the piece of equipment employed and

the use to which it is put—the efficiency of utilization of

apparatus—to the end that the best results may be obtained

and the best conditions exist in all varieties of commercial

transactions.

Individual weights and measures officials in striving to obtain the ideal condition in this respect in their jurisdictions

have naturally come to recognize the important part which

the principle involved plays in their work. However, the

subject has, it seems, been but little emphasized in official publications usually in their hands. What information has

been available along these lines has been in the catalogues

or other publications of manufacturers of weighing and measuring devices. In relation to these, in general, we may state

that it is no part of our purpose in what follows to disparage

them as a source of useful information. That some of these

publications contain material of value is not to be gainsaid.

Certainly, in so far as his own product is concerned, the

manufacturer is in an excellent position to recommend specific

types for particular needs. Such suggestions deserve and

should receive the careful attention of the official and of the

purchaser.

It is obvious, however, that manufacturers' catalogues will

almost necessarily confine their discussions to one kind and

make of apparatus; they will not have occasion to present

the whole subject in its broader and more general aspects.

Moreover, since these publications naturally have as their

primary or underlying purpose the sale of specific products, it may reasonably be supposed that the official has often discounted the contents thereof to some extent in the not unnatural belief that the suggestions advanced can hardly be

wholly unprejudiced ones. Therefore such an article as this
SUITABILITY OF EQUIPMENT 3

seems none the less necessary. Likewise, there have not been

available to the ordinary purchaser any general constructive

suggestions which he has recognized as being unbiased, for

the source mentioned above is likely to be discounted in this case as in the other. Again an official presentation of the

underlying principles may serve a useful purpose.

Proceeding to this presentation, it may first be observed

that the purchaser of commercial apparatus will not have

taken sufficient precautions if he merely selects a piece of

apparatus in compliance with the code applicable to devices

of the character of the one purchased, failing to give attention

to any additional considerations. Likewise, the weights and

measures official will not be exercising proper and efficient

supervision over the apparatus in commercial use if he merely

inspects and tests apparatus and seals or condemns it solely

because it complies or does not comply with the specifications and tolerances applicable to it, at the same time

neglecting to examine into the conditions surrounding its use. For while it is to be taken for granted that every piece of

apparatus complying with proper specifications and toler- ances is, in general, a proper one, it by no means follows that

every such piece of apparatus is efficient, or even satisfactory,

for every use. But little consideration will be necessary to indicate the

truth of this postulate. Few would be found to defend practices such as attempting, in commercial transactions, to determine the weight of a ton of coal on a railroad track scale,

of 50 pounds of fertilizer on an autotruck scale, of 10 pounds

of sugar on a portable platform scale, of 5 grains of an ex- pensive or potent drug, to be used in compounding a prescription, on a counter scale, or of 50 milligrams of a radium salt even on a prescription scale. Nor would this be on account

of the fact that the railroad track scale, the autotruck scale,
4 NATIONAL BUREAU OF STANDARDS

the portable platform scale, the counter scale, and the prescription scale were not, in themselves, entirely satisfactory

weighing machines. Each might well be of excellent design

and construction, and in proper condition. It would rather

be because each scale was employed in a use for which it was

not designed and constructed and for which it was entirely

unsuited. And yet, while it is undoubtedly uncommon, it has not been by any means unknown for scales to be misused

in ways not unlike those mentioned.

It is, in short, essential that the purchaser of apparatus

and the weights and measures official, in buying or in ex- amining, respectively, apparatus intended for a certain use or being put to a certain use, should each satisfy himself that

the piece of apparatus selected or employed is well designed

for that particular use. Failure to observe these precautions

may result in the owner receiving unsatisfactory service, and

the amounts of commodity entering into commercial transactions being seriously inaccurate, even when due care is being exercised to secure the best results capable of being

produced by the apparatus employed.

To be sure the weights and measures official will often not

be in a position to condemn apparatus in use even though

he may consider that it is not ideally suited to the use for

which it is employed, nor is it even desirable that he have

such broad powers. However, if serious inaccuracies are resulting, his authority will doubtless be found sufficient to correct conditions either directly by proceeding against the apparatus itself, or indirectly, but perhaps not less effectively, by

proceeding against the amounts of commodities determined.

Also, even in cases where mandatory action is not indicated,

he can furnish valuable service by assisting a prospective

purchaser to make a wise selection on the one hand, or by

pointing out the inefficiencies in the case of apparatus in use on the other.
SUITABILITY OF EQUIPMENT 5

In these cases the official will naturally take care to give

general advice only, covering such points as accuracy desirable, preferable capacity of device, whether one or more devices will probably be needed, etc., leaving to the purchaser in

every case the decision as to the merits of similar products of

the different makers. Also, when the various devices under

consideration all comply with the specifications and toler- ances in force, it will, we believe, be much the wiser course

for the official to refrain from differentiating between devices

designed upon different principles but intended for identical

uses. In other words, considerations such as convenience,

speed of operation, durability, etc., should be evaluated by

the purchaser. We have in mind the undesirability of comparison of the relative merits of beam scales and automatic

scales, spring scales and pendulum scales, piston-type and

visible-type Kquid-measuring devices, and meters, etc.—such

matters as these should be left to the salesmen for presentation. The purchaser should inform himself along these lines

and draw his own conclusions without the interposition of the

official. Failure on the part of the official to observe this

precaution is likely to lead him into serious difficulty even when his motives are above reproach.

Contrary to the practice in this country, which will be

described later, some foreign countries adopt the practice of

officially placing restrictions upon the type of apparatus

allowable for particular uses. To mention one specific ex- ample, in England the regulations corresponding to our specifications and tolerances provide for three classes of "beam

scales" (defined as equal-arm weighing instruments, the pans

of which are below the beam), namely, classes A, B, and C.

To each of these classes are applied independent requirements as to sensitiveness and accuracy. "Special trades"

are then tabulated and the class or classes of scale required

to be used in these trades are noted. Under such conditions
6 NATIONAL BUKEAU OF STANDARDS

the purchaser of a scale, by being restricted in his choice, is guided as to the type to be selected.

In this country we have few such restrictions as these,

and if a proper enforcement of law can be procured without

them it would be our judgment that under conditions as they

exist in this country it is best to allow the purchaser the

greatest freedom of choice. It has always been considered

that were the attempt to be made to lay down particular

requirements for the kinds of apparatus to be put to various

uses, the task of the weights and measures official would be

greatly complicated—perhaps the majority of the weights and

measures offices as at present constituted would find it impossible adequately to enforce the requirements. For these reasons the specifications and tolerances usually adopted here

are general in their character, they are drawn broadly to cover

devices of certain general types, and they do not generally

attempt to define or restrict the uses to which apparatus

may be put.1 Thus the selection of equipment here is more

untrammeled than in England, but for this reason a purchaser should, both on his own account and for the protection of those with whom he deals, feel more, rather than less,

obligated properly to select apparatus satisfactory and adequate for the use to which it is to be put.

In any event even were the attempt to be made to require

specific types for particular uses this object would probably

best be accomplished in this country by rule and regulation

promulgated by the individual offices rather than by specifii There are several minor exceptions to this general statement; thus scales for the sale of foodstuffs other than vegetables at retail shall have graduations of 1 ounce or less (counter

scales, specification No. 10a); baskets of a less capacity than one-half bushel shall not be used

as dry measures (dry capacity measures, specification No. 8) except only for berries and small

fruits (berry baskets or boxes, specification No. 1) ; the pans of scales for the sale of fish or other wet commodities shall be so constructed as to provide for drainage (scales, general specifications, No. 23) ; and prescription scales and balances of class B may only be used in weighing loads o£ 10 grains or more (prescription scales and balances, class B, specifications), etc,
SUITABILITY OP EQUIPMENT 7

cations and tolerances designed for national acceptance.

This is for two reasons : First, the manner of use of apparatus

is, under our system of law, the prerogative of the States, and

they should be left entire freedom to work out these details

in the manner which seems to them best. Second, the specifications and tolerances are not only guides for the weights

and measures official in the enforcement of law but they also serve the very important purpose of advising the manufacturer of weighing and measuring devices as to what apparatus

will be satisfactory in many of our far-flung jurisdictions.

The approval of type by the Board of Trade appears to subordinate this purpose in England. As we understand it, their specifications may be said to serve as general guides

only ; each design produced by each maker is considered on its individual merits, and must be approved before it is put on

the market for commercial use. Since we do not have any

Federal approval of type of apparatus—and State approval

in relatively few jurisdictions—the specifications and toler- ances must become primarily the sole reliance of the manufacturer in judging whether his product will be satisfactory.

They should, therefore, be prepared in the form which will

be of most use to the manufacturer.

It seems, then, best that they be not complicated by

specifications concerning the particular uses to which

specific types may be put. For after all the manufacturer of the apparatus is not, perhaps, primarily concerned

with this—certainly in most cases he can not be held generally

responsible for the use in which a device which he produces

may be employed. When he produces apparatus complying

with the specifications and tolerances he fulfills the only duty

to which he can be held strictly to account. He will, and

usually does, when practicable, go further than this; to secure customer satisfaction; he will endeavor to see to it that the
8 NATIONAL BUREAU OF STANDARDS

purchaser secures apparatus nicely fitted to his particular

needs. But since he will often not be fully advised as to the condition under which the apparatus is to be used, and

since, in any event, a manufacturer will practically be

obliged to sell the particular device ordered, the onus of

securing a device properly fitted to the particular need

must, in the final analysis, be borne by the purchaser.

One further word may be added in regard to the character

of the requirements contained in the specifications and tol- erances. We feel that the principal object to be attained by

specifications and tolerances is to eliminate from commercial

use generally unsatisfactory commercial types. The desirable concomitant is to secure in place of the discarded apparatus constantly improving types. This latter condition will

be most effectively secured not by hedging the manufacturer

about with specific and restrictive specifications, but rather

by allowing his initiative the fullest play. The specifications and tolerances have, therefore, been designed to inform

the manufacturer in general language of the fundamental

considerations believed to be vital to the construction of

proper apparatus, and of some forms of construction found

by experience not to result in accuracy, dependability, or

fair dealing in the field. Within these broad limits the manufacturer has been left the greatest latitude possible in the

working out of his designs.

In the above, attention has been invited to the importance of careful analysis in arriving at a decision as to the

suitability of apparatus for particular purposes. In the

remainder a few general principles will be given and a few

examples cited to assist in describing the nature of this

analysis. These will not by any means cover the field, but

they may serve as examples of the proper method of attack.

In the first place, a general comment may be made on

the relation of price of commodity and accuracy of deter-
SUITABILITY OF EQUIPMENT 9

mination. It is almost universally accepted as being good

business practice to consider that required accuracy of weighing is roughly proportional to the value of the commodity

sold. In wholesale dealings this may be illustrated by the

fact that the Interstate Commerce Commission regulations

provide that claims may be filed against railroad companies

in the case of wheat in carload lots if the discrepancy found

is greater than }/$ per cent; in the case of coal, a discrepancy

eight times as great, or 1 per cent, is allowable. This is doubtless due, at least in part, to the fact that the latter is a very much cheaper commodity than the former. This is further indicated by the fact that the tolerances recommended

by that body for grain scales and for general purpose scales are 0.1 per cent and 0.2 per cent, respectively. While this

principle does not seem entirely consistent at first glance—an

error of 1 per cent or 1 cent on the dollar would seem to be

of equal importance in the case of a purchase of a certain

number of dollars' worth of any commodity—nevertheless, it

is doubtless a reasonable and also a necessary commercial

practice since, as a rule, in wholesale transactions at least,

the higher the price of a commodity the smaller will be the

margin upon which it is handled, and thus there is probably

a legitimate need for higher accuracy of determination of

quantity in the case of the higher priced commodities.

In retail sales of commodities it is doubtless not generally

true that the margin is smaller in the case of the higher

priced commodities. At retail, however, attention will often

be focused on the shortage per purchase and the resulting

discrepancy in terms of value. Let us consider in these terms,

for the sake of illustration, a shortage of one-half ounce on a purchase of various food commodities procurable at grocery

stores or delicatessens. * 112054°—29 2
10 NATIONAL BUREAU OP STANDARDS

Commodity

Ordinary

price per pound

Supposed

error

Resulting over- charge

per pur- chase

Cents Ounce Cents Potatoes Sugar

Rice Spinach Domestic cheese

710

1532

4 0. 125 .22

.31 .47

1.0

1/2 Butter. 5580

100

125 150

1.7 2.5

3.1 3.9

4.7

Boiled ham. Tea

Shelled nuts

Chocolates._ We believe that in the minds of the great majority the

error on the lower-priced commodity will seem a less serious

matter than the same error in the higher range of the table,

and the conclusion will be that the latter should be some- what more accurately weighed than the former. While we

have no quarrel with this conclusion, nevertheless we should

not allow it to influence us to disregard any unjustifiable

errors in commercial transactions, be the value of the commodity involved great or small.

Therefore, one of the things to be kept in mind in the

selection of a piece of apparatus is the value of the commodities which are to be bought or sold, and the general criterion

to be applied is that the kigher the value of the commodity

the greater the accuracy which should be sought.

In buying weighing apparatus for a particular purpose

two important factors are to be borne in mind; one is the

weights of the heaviest and of the lightest drafts which must

be handled, and the other, the required percentage accuracy

in the weights of the commodity—or of the highest priced

of the several commodities—to be weighed. From these

figures two things can be determined: First, whether one

device will suffice or whether more than one must be pro-
SUITABILITY OP EQUIPMENT 11

cured, for a scale with a large enough capacity to weigh the

heaviest draft may not weigh the lighter drafts within the

required accuracy; and, second, the best type and capacity

of the device or devices. In general, the scale purchased

should be of a capacity only moderately in excess of the

heaviest draft to be weighed in practice—perhaps the nearest higher capacity ordinarily marketed. It is believed to be a mistake to procure a scale of a very much greater

capacity than will be needed in the normal course of business,

since required sensitiveness and accuracy will often be sacrificed thereby. Again, for the same reason, a scale should

not be used in weighing loads which are too small a fraction

of its capacity. It will be found to be good economy to make

the investment in additional apparatus wiien such apparatus

is indicated to be necessary.

Much the same considerations govern in the case of a widely different kind of apparatus, namely, glass graduates.

In the case of cylindrical graduates, about the same absolute

accuracy can be obtained at each graduation and e&ch graduation is subject to almost the same error. The reason is that

the original placing of the graduation and the accuracy with

which any measured quantity can be brought into coincidence

with the graduation are functions of vertical displacement from

the correct position of the surface of the liquid rather than

of the volume measured. The result is that the percentage

accuracy is almost exactly proportional to the quantity being

measured.. For instance, in the case of a cylindrical graduate

of 4-ounce capacity having a diameter of 0.6 inch, a maximum

error of measurement of about 15 minims would not be excessive at any graduation which is itself in error by the full amount of the tolerance allowed. This would be an error of

0.8 per cent on a measured quantity equal to the capacity

of the graduate. On a measured quantity of one-half ounce,
12 NATIONAL BUREAU OF STANDARDS

however, were the same absolute error to be made, the percentage error would be 6.4 per cent of the measured quantity.

The advisability of not using a cylindrical graduate at too

small a percentage of its capacity, and the desirability of

supplying several sizes when quantities varying considerably

in amount are regularly to be measured, is obvious. It is considerations such as these which have induced the National

Bureau of Standards to make the recommendation to glass- ware manufacturers that approximately the first 10 per

cent of the capacity of precision cylinders be left ungraduated.

In selecting a scale a factor which at first glance may be

considered a minor matter, namely, the value of the minimum

graduation, will be found to be of considerable importance

when the requirements of the specifications are carefully

analyzed. It will be discovered that a reduction in value of

the minimum graduations on the beam or reading face, results

in many instances in a reduction in the values of the minimum tolerance and of the sensibility reciprocal demanded by

the specifications, the two latter values being directly dependent on the former. This is a reasonable demand, since a scale

with a small minimum graduation holds itself out as being

capable of giving more accurate results than a scale not so

finely graduated; and this representation should be fulfilled. Therefore it is provided that the minimum tolerance on a used platform scale of the beam type shall in no case be less

than the value of one of the minimum graduations on the

beam; likewise the maximum sensibility reciprocal is the

value of two of these graduations.2 Similarly it is provided

that the minimum tolerance on an automatic-indicating

counter scale or on a spring scale, not new, shall in no case be

less than one-fourth of the minimum graduation on the reading face or dial.3

2 See "Platform scales"—"Sensibility reciprocal," and "Tolerances," pp. 86, 87.

* See "Counter scales" and "Spring scales"—" Tolerances," pp. 97, 101.
SUITABILITY OF EQUIPMENT 13

Now the smaller the tolerance and the sensibility reciprocal, the greater the refinement of parts necessary, to construct

a scale of the required accuracy and sensitiveness. Also it will be found more difficult to maintain the scale in conformity with the more rigid requirements. In spite of this there

should be no hesitation on the part of the purchaser to pro- cure a scale having a sufficient sensitiveness and accuracy

to enable him satisfactorily to weigh the smallest amount of

the most expensive commodity normally to be weighed. On

the other hand, the considerations indicate that he will be

wise not to select a scale which is more finely graduated than

is necessary.

We have seen that it is often advisible to furnish more

than one device when the amounts of commodity to be

weighed differ greatly. In the case cited in the preceding

paragraph, if commodities differing widely in price and

quality are to be weighed, the wisest course of all might well

be to procure two devices of the same capacity, one to be of

higher accuracy and more sensitive than the other, and perhaps of greater general refinement. The first will be kept

in the best possible condition by reserving it for the commodities of high price and quality; the other can be utilized to

perform the rougher work. Many merchants have recognized the benefits accruing from such a procedure and have

put it into effect with excellent results. The specifications

for prescription scales and balances, providing as they do

for class A and class B scales, specifically recognize the desirability of this principle in the case of prescription work.

Another example of proper selection somewhat analogous

to the above involves the factor of the ability to perform

certain operations within tolerances or the ability to indicate

with certain accuracies in the case of devices other than scales.

Thus, there is incorporated in one or two of the codes of speci-
14 NATIONAL BUREAU OF STANDARDS

fications a principle which may be stated as follows: Apparatus must be so designed and constructed that it will successfully perform those operations which it purports to be

able to perform, within the tolerance provided for such operations. For instance, if a liquid-measuring device has a graduation representing the first pint, quart, or half gallon, then

such a device obviously holds itself out as capable of delivering a pint, or quart, or one-half gallon of liquid within

the tolerance allowable on such a delivery—2 cubic

inches—and consequently it is required that it be susceptible

of being so operated. However, if 1 gallon is the first graduation, then it will be satisfactory if it is susceptible of being

operated within the tolerance on this amount—3 cubic

inches. If in the ordinary course of business it is to be ex- pected that amounts less than 1 gallon will rarely or never be called for, then for the sake of obtaining the larger minimum tolerance it would seem to be good judgment to pick a

device which does not purport to deliver less than this amount.

A sale of a smaller quantity could be made, if occasion should

arise, by the utilization of an inexpensive liquid measure. As a final example of the character of factors important

in the selection of a piece of equipment—in this case conditions of installation are also involved—we will briefly dis- cuss a meter intended for use in a filling station retailing

gasoline. In this case the most prominent factors in the

mind of the purchaser will probably be accuracy and speed

of service to automobiles; the latter factor will probably be

considered by the purchaser as synonymous with maximum

delivery rate. How are these to be evaluated?

More than one size of meter can be secured for this service having different maximum and minimum rates; also the

maximum rate can be made to vary over a considerable range

of values according to installation conditions. In deciding
SUITABILITY OF EQUIPMENT 15

upon the proper maximum rate (the supposed speed factor)

it should be borne in mind that dependability of delivery at all delivery rates (the accuracy factor) is ordinarily more readily

obtained when there is not too great a range between the maximum and minimum rates, and that in effect only the former can be varied, since the specifications dictate that the minimum rate may in no case be considered to be greater than 7

gallons per minute.4 Another consideration involving accu- racy versus speed is that it is difficult to stop the indicator

accurately at the desired amount when it is moving very

rapidly over the dial as the result of a high delivery rate; thus, the flow may be stopped too soon, requiring a "cracking" of the delivery valve to bring the indicator to the proper

point, or it may not be stopped soon enough, with a resulting

overdelivery. Finally, in case gasoline is furnished too fast

to a car, spillage, resulting not only in shortage in the delivery but also in tending to customer dissatisfaction and constituting a fire hazard, is the very probable result. It has also been suggested above that speed of delivery

to cars and maximum delivery rate are not necessarily synonymous ideas. Anomalous as this statement may sound, it

is true that the one may not always follow the other. In

the development of this idea it may be said that it is probable

that few cars will take gasoline much faster than 20 gallons

per minute and that investigations seem to indicate that for

many of them a slower rate of delivery than this must be

employed. Now difficulty will probably be encountered in

the slowing down of the delivery to just the proper speed in

each case by the expedient of a partial closing of the delivery

valve. Thus when some valve closure is indicated by experience to be necessary it is probable that to be on the safe

side the operator will be inclined to close the valve somewhat

* See "Liquid.measuring devices," Spec, No, 8, p, 51,
16 NATIONAL BUREAU OF STANDARDS

more than is necessary. In delivery to some cars, then, a high delivery rate may result in a slower delivery than would

result from a slower rate. From the above it will be apparent that a careful analysis

of the various factors involved will be well repaid. In this

instance it may convince the purchaser that too high a delivery

rate may not only result in incorrect deliveries and other disadvantages but that it may even defeat its own purpose and

not actually result in a greater speed of delivery to the average

car served.

General Conclusions.—A few general conclusions may

be adduced from the above discussion, as follows:

A user should not procure weighing or measuring apparatus of a considerably larger size or capacity than is required

to meet his needs. In doing so he will usually be sacrificing

sensitiveness and accuracy and thus unnecessarily increasing the percentage errors of his determinations.

It is inadvisable to provide only one piece of apparatus to be used over an unjustifiably large range, and especially

at too small a percentage of its total size or capacity, when

two or more pieces will increase the accuracy of determination. To do so is ordinarily poor economy.

A low-grade and inaccurate type of apparatus should never be employed when it is indicated that a better and more

accurate type is advisable. Conversely, it is uneconomical

to procure an unnecessarily high-grade piece of apparatus to do work which could be satisfactorily handled by something

of a lower and less expensive grade. Often two devices will

be the proper solution.

A buyer should first familiarize himself with the specifications and tolerances applicable to the character of a

device to be purchased and determine the various factors of

importance in connection with the work which the apparatus
SUITABILITY OF EQUIPMENT 17

to be procured will be required to perform. With all these

facts in mind he should analyze the various features of

the available apparatus and purchase only when he has

assured himself that the proper type of device has been found.

Finally, it is felt that there can be no better advice in

closing than the following comment. Never purchase a

piece of apparatus for commercial use without a guaranty

from the seller that in case the weights and measures official refuses to approve it a new and satisfactory piece of apparatus

will be furnished, the original purchase price refunded, or

other satisfactory adjustment made. This guaranty will,

we believe, be given by the seller in almost every case without hesitation; and it seems reasonable to demand it, since

the seller should certainly be in a better position than the

buyer to judge as to the compliance of the piece of apparatus

with the official requirements.
Part II.—SPECIFICATIONS AND TOLERANCES FOR

COMMERCIAL WEIGHTS AND MEASURES AND

WEIGHING AND MEASURING DEVICES, AS

ADOPTED BY THE NATIONAL CONFERENCE ON

WEIGHTS AND MEASURES AND RECOMMENDED

BY THE NATIONAL BUREAU OF STANDARDS FOR

ADOPTION BY THE SEVERAL STATES

INTRODUCTION

Source.—The specifications and tolerances given herein

comprise, in their latest form, all the codes which have been

adopted from time to time by the National Conference on

Weights and Measures,6 the latest action reported having

been taken by the Twenty-first National Conference on

Weights and Measures in 1928. The conference committee on specifications and tolerances,6 acting at the request of the

conference or upon its own initiative, prepares, with the

cooperation of the National Bureau of Standards, proposed

amendments or additions to the material previously adopted

by the conference; such amendments or additions are then

presented to the conference as a whole, where they are discussed by weights and measures officials and representatives

of interested manufacturers or industries; eventually the

5 The National Conference on Weights and Measures, known until 1925 as the Annual Conference on Weights and Measures, is a body made up of State and local weights and measures

officials from all parts of the United States which meets annually at the National Bureau of Standards, Washington, D. C . For a more detailed description of the conference and its activities, see chapter 12, Bureau of Standards Handbook No. 11, Weights and Measures Administration. Copies of this publication may be pure-based from the Superintendent of Documents, Government Printing Office, Washington, D. C, at 70 cents each.

6 A standing committee of the national conference, consisting of five members, the present chairman being F. S. Holbrook, of the stafi of the National Bureau of Standards, 18
INTRODUCTION 19

proposals of the committee, which may have been amended

on the floor, are voted upon by the weights and measures

officials, a majority vote being required for adoption. New

codes and major changes in existing codes are first adopted

tentatively, final action being deferred at least until the suc- ceeding conference; sometimes a code will retain its tentative status for two years.

All of the specifications and tolerances given herein are recommended by the National Bureau of Standards for

official promulgation in and use by the several States in

exercising their control of commercial weighing and measuring apparatus; in the absence of a State department of weights

and measures, a similar recommendation is made with

respect to the local jurisdictions within such a State.

Purpose.—The purpose of specifications and tolerances is to eliminate from use, without prejudice to apparatus which

conforms as closely as practicable to the official standards,

weights and measures and weighing and measuring devices

which are false, which are of such construction that they are faulty—that is, which are not reasonably permanent in their

adjustment or will not repeat their indications correctly—or which facilitate the perpetration of fraud.

Application.—The specifications and tolerances given herein are intended to apply to weights and measures and weighing and measuring devices used in commercial transactions.

With respect to any particular commercial device the specifications and tolerances are to be construed as being fully

applicable whenever such a device falls clearly within one or more of the several classes of apparatus specifically considered.

They shall also be construed to apply to other apparatus,

such as that used for special purposes, whenever and in so

far as they are clearly applicable, but not otherwise,
20 NATIONAL BUREAU OF STANDARDS

Classification of Specifications.—Two classes of specifications are established:

1. Retroactive specifications (printed in ordinary roman

type) which are to be enforced with respect to all commercial

apparatus in use.

2. Nonretroactive specifications (printed in italics) which

are to be enforced only with respect to apparatus which is manufactured in or brought into the State after the promulgation of the specifications therein, and which are not to be

enforced with respect to apparatus which is in the State at

the time of such promulgation, either in use or in the stock

of manufacturers of or dealers in such apparatus.

This classification is made in order that the requirements

may be put into force and effect without unnecessary hardship and without wholesale condemnation of apparatus which,

while not of the best construction, is nevertheless fairly satisfactory and may be used for some time without greatly

prejudicing the rights of purchasers. The retroactive specifications are those which are most urgently required and with

which all apparatus should at once be required to conform;

the nonretroactive specifications are those which, while

clearly desirable, are less vital, and which, as a matter of

expediency in enforcement, may reasonably be suspended

with respect to apparatus in use. In order to enforce the specifications, it will be necessary

to be able to distinguish that apparatus to which the

nonretroactive specifications do not apply; that is, that

apparatus which was in the State, either in use or in the stocks

of manufacturers or dealers, at the time of promulgation of

the specifications. This may be accomplished as follows: At

the time of the first examination of apparatus, all devices

encountered, and sealed, as the result of an accuracy test and

an inspection involving the application of the retroactive
INTRODUCTION 21

specifications oniy, may be permanently and clearly stamped

in a prominent position, preferably near the seal, with a steel

die bearing a star (*) or some other simple design. Not only

apparatus in use but also that in the stocks of manufacturers

and dealers should be marked as described. After the first examination, all apparatus not so marked will be subject to

all of the specifications, both retroactive and nonretroactive,

while the apparatus marked with the special stamp will continue to be exempt from the provisions of the nonretroactive

specifications and will be regulated only by the retroactive

ones.

Classification of Tolerances.—Two classes of tolerances, or maximum allowable errors, have been established:

1. Manufacturers' tolerances, or the tolerances on new

apparatus.

2. Users' tolerances, or the tolerances on apparatus in use. This classification is made because, in general, apparatus

will necessarily deteriorate after being put into use and used

for some time, and it would be manifestly unjust to reject or condemn, shortly after it is put into use and used, apparatus

which was satisfactory when sold. It might so happen that

the new apparatus had been just within tolerance when it was approved ; it is obvious that but very little use might be

necessary to throw the error on such apparatus outside the

tolerance; therefore such a piece of apparatus would have

an unreasonably short commercial life if it were not for the

larger tolerance for apparatus in use, such as has been

provided.

After weights and measures territory has once been covered

it is customary to consider as "new" all apparatus wilich is subsequently being tested for the first time by the official, and

to apply to such apparatus the manufacturers' tolerances.

It is likewise customary to apply the manufacturers' toler-
22 NATIONAL BUREAU OF STANDARDS

ances in many cases when retesting apparatus which has been

rejected and which has subsequently been adjusted or repaired,

for the same reasons as have been outlined above.

It may also be mentioned that there are certain types of

apparatus with respect to which the general principle of loss

of accuracy with use does not apply, such as graduated glassware, milk bottles, etc. Therefore in the tolerances which

are given hereafter it will be observed that in certain instances

but a single tolerance is specified. Wherever no mention is made of manufacturers' tolerances, it is to be understood

that the same tolerance applies to new and to old apparatus.

Where two classes of tolerances are specified, the manufacturers' tolerances are one-half the users' tolerances; since

the latter will be employed more frequently than the former,

the values appearing in the tolerance tables which are given

hereafter are the users' tolerances, and the values for the

manufacturers' tolerances will be one-half of those given in

the tables.

Correct and Incorrect Apparatus Defined.—A weight or measure or weighing or measuring device which is defined as correct shall be understood and construed to mean only one which conforms to the standard within the tolerance, under the

method of test prescribed, and which, in addition, complies

with all the specifications applicable to it given in the following pages. All other weights and measures and weighing and

measuring devices shall be understood and contrued to be

incorrect.

Apparatus in the Metric System.—No specifications contained in the following pages shall be understood or con- strued to prohibit the sale or use of weights or measures or weighing or measuring devices constructed or graduated in

units of the metric system.
LINEAR MEASURES 23

The tolerances to be allowed on any weight or measure or weighing or measuring device constructed or graduated in

units of the metric system shall be the same as those specified on similar apparatus of an equivalent size or at an equivalent

load in the customary system.

SPECIFICATIONS AND TOLERANCES

Specifications printed in roman type are retroactive, and

apply to all apparatus.

Specifications printed in italics are nonretroactive and apply

only to apparatus manufactured in or brought into the State

after the date of promulgation of the specifications.

LINEAR MEASURES

Specifications.—1. Measures of length shall be made of a material the form and dimensions of which remain reason- ably permanent under normal conditions—for example, steel,

brass, hardwood, etc.

2. The ends of measures of length made of wood, or of other

nonmetallic material liable to wear away through use, shall he

protected by some metal not softer than brass, firmly attached

to the measure.

3. Rigid measures of length shall be smooth and straight.

4. Folding measures of length shall be so constructed that

each section will come to a definite stop when straightened

out.

5. Measures of length shall be graduated in units of the

customary system and its usual subdivisions.

6. All graduations shall be clear and distinct, and the

main graduations shall be plainly designated. The length

of these main graduations shall be greater than that of the

intermediate graduations, and the latter shall be varied in

length in such a way that they may be conveniently read.
24 NATIONAL BUREAU OF STANDARDS

Main graduations are to be construed as those the value of

which should be readily ascertainable in order to facilitate

reading at any point.

7. Graduations shall not be greater in width than onequarter of the value of the smallest subdivision: Provided,

however. That if line graduations are employed, their width

shall not exceed 0.03 inch; if raised graduations are employed, their width shall not exceed 0.12 inch at their widest

point.

8. All graduations shall be uniformly spaced and be perpendicular to the edge of the measure.

9. Measures of length, so called, defined by tacks driven

into a counter, or in any similar way, shall not be allowed.

Tolerances.—The tolerances to be allowed in excess or

deficiency on all measures of length, except tapes of steel or other metal, shall be the values shown in the following table:

Provided, however, That the manufacturers' tolerances or the

tolerances to be allowed on all new measures of length, except

tapes of steel or other metal, shall be one-half of the values

given.

Length Tolerance

Feet Inch 6 3/16

5 5/32

4 1/8 3 3/32

2 1/16

1 1/32

1/2 1 1/64

i Or less.
FABRIC-MEASURING DEVICES 25

The tolerances to be allowed in excess or deficiency on all tapes of steel or other metal shall be the values shown in the

following table:

Length Tolerance Tension

Feet Inch Pounds 100 1/4 10 66 3/16 10 50 1/8 10 33 3/32 10 25 1/16 10 10 1/16 5 6 1/32 5

3 1/32 5 FABRIC-MEASURING DEVICES

Definition.—A retail fabric-measuring device, hereinafter

referred to as a fabric-measuring device, is a mechanism or machine which is adapted to measure and to indicate automatically the length of fabric passed through it, and which, on

account of the character of its primary indicating elements,

is obviously designed for use in connection with retail sales;

such devices may or may not be designed to indicate automatically the total price of the amount of material measured, for a series of unit prices.

Specifications.—1. Basis of Graduation.—Fabric-measuring devices shall be graduated in units of the customary

system and its usual subdivisions. The maximum value of

the minimum length graduations on fabric-measuring devices

shall be one-eighth yard.

2. Character of Graduations.—The length graduations

and the value graduations on all fabric-measuring devices

shall be clear and distinct and their length shall be so varied

112054°—29 3
26 NATIONAL BUREAU OF STANDARDS

or they shall be so arranged that their meaning or value is readily apparent and their indications may be conveniently

read. The width of any graduation mark shall in no case be

less than 0.008 inch.

3. Interval Between Graduations,—The clear interval between one-eight yard graduation marks on fabricmeasuring devices shall not be less than eleven-sixteenths

inch (0.6875 inch); if inch graduation marks are employed

the clear interval between such inch graduation marks shall

not be less than one-eighth inch (0.125 inch). These values

shall be applied to the most sensitive indicating element

with which the device is equipped.

The clear interval between value graduation marks on

fabric-measuring devices shall not be less than 0.02 inch.

4. Computing Charts.—Computing charts may be made

in accordance with either of the following principles:

(a) If the device is so designed and constructed that it purports automatically to compute for a series of unit prices

the total price for every length within the range of the device,

then the device shall be equipped with a value pointer or indicator and value graduation marks; the value graduation

marks shall be correctly placed; and in any position which

the indicator or pointer and the chart may assume there shall

be exposed to view a sufficient number of value figures and

graduations to permit the value indications of the device to

be read correctly. The value graduations shall not exceed

1 cent at all prices per yard up to and including 30 cents. At any higher price per yard the value graduations shall not

exceed 2 cents : Provided, however, That nothing in the above

shall be construed to prevent the placing of a special value

graduation to represent each 5-cent interval. These special

graduations may take the form of dots, staggered graduations, or similar forms. They shall be so placed that their
FABRIC-MEASURING DEVICES 27

meaning and value may be clearly understood, but they shall

not be placed in the space between the regular graduations.

(b) If the device is so designed and constructed that it purports automatically to compute only for lengths corre- sponding to a definite series of length graduations, then there

shall be no value graduation marks, and at no position which

the chart may assume shall two value figures for the same unit

price be completely and clearly exposed to view at the same

time. One of the following alternatives shall also be compiled

with:

(1) There shall be a value computation for each length

graduation throughout the range of the device; or

(2) No value indication may be exposed to view except

at such times that the device registers a length indication

for which a correct value indication is provided; or

(3) Each column or row of value graduations shall be

clearly and conspicuously marked with the length graduation to which the values correspond, the device shall be

marked with the character and limitations of the computations made, and there shall be a computation for at least

each one-eighth yard throughout the range of the device.

All money values corresponding to definite length graduations must be mathematically correct except as follows : If the

mathematically correct amount includes a fractional part of a

cent, the fraction shall be dropped if it is less than 3^, but if the fraction is or more the next higher cent may be shown.

5. Pointers and Indicators.—Each pointer or indicator

used in a fabric-measuring device shall be so designed and

constructed that a clear, distinct, and accurate reading is given. All pointers or indicators shall be symmetrical about

the graduation marks at which they may stand and shall

reach to all such graduation marks. The width of the pointer

or indicator, or of the end thereof, shall not exceed the
28 NATIONAL BUREAU OF STANDARDS

width of the smallest graduation marks on the scale with

which it is used, and in no case shall such width exceed

0.015 inch. The distance between the pointer or indicator

and its scale or chart shall not exceed 0.06 inch.

6. Readability of Indications.—Fabric-measuring devices shall be so designed and constructed that in any position which the length indicator or pointer and scale or chart

may assume in their operation, there will be exposed to view

a sufficient number of figures and graduations readily to permit the length indications of the device to be read correctly.

7. Return of Indicating Element to Zero.—Fabricmeasuring devices shall be so designed and constructed that

the indicating elements used in registering lengths or prices

of deliveries to individual purchasers are returnable readily

to a definite and clear zero reading before the next measuring

operation is begun.

8. Increasing and Decreasing Indications.—All fabricmeasuring devices shall be correct in their length and value

indications whether the indications are being increased or

decreased.

9. Limitation of Use.—If a fabric-measuring device will

not give correct results when used for the measurement of all fabrics, then the device shall be so marked as clearly to indicate its limitations.

10. Lettering and Graduations.—All markings, instructions, figures, and graduations required under these specifications shall be of such size, design, material, and location and

shall be so applied or affixed that they will not tend easily to

become obliterated or illegible.

11. Fraudulent Construction.—Ail fabric-measuring

devices and all devices designed to be attached thereto and

used in connection therewith shall be of such design and

construction that they do not facilitate the perpetration of

fraud.
FABRIC-MEASURING DEVICES 29

Tolerances.—The tolerances to be allowed on the delivery 7 of fabric-measuring devices in excess (underregistration of

device) and in deficiency (overregistration of device), to be

applied on both increasing and decreasing registrations of the

machine, shall be the values shown in the following table:

Provided, however, That the manufacturers' tolerances or the tolerances on all new fabric-measuring devices shall be

one-half of the values given:

Machine

indication

Tolerances on delivery •

In deficiency

(overregis- tration) In excess (underregistration) Yards Inch Indies

1

b 1/4 3/8 2 1/4 3/8

3 5/16 3/8

4 5/16 1/2 5 3/8 5/8

6 3/8 3/4 7 1/2 1 8 1/2 1 9 5/8 iH

10 — 3/4 m

11 3/4 m 12 7/8 m 13 7/8 m 14 1 2 15 1 2

See footnote 7 below. b Or less. For machine indications of more than 15 yards add onesixteenth inch in deficiency and one-eighth inch in excess per indicated yard.

7 "Tolerances on delivery" refers to the variations between the indications of the fabric- measuring device and the corresponding actual lengths of testing strip passed through the

device, and does not apply to check measurements made upon lengths of fabrics which have

been commercially measured.
30 NATIONAL BUREAU OF STANDARDS

TAXIMETERS

Definitions.—A "taximeter" is a machine adapted automatically to calculate, at a predetermined rate or rates, and

to register, the charge for hire of a vehicle.

The "fare" is that portion of the charge to be paid by the

passenger for the hire of a vehicle, which is automatically

calculated by the taximeter through the operation of the

mileage mechanism, the time mechanism, or a combination

of these.

The "extras" are those charges which are to be paid by

the passenger in addition to the fare, and include any charge

at a flat rate assessed for the transportation of passengers in

excess of a stated minimum number as well as any charge

for the transportation of baggage.

The "face" of a taximeter is that side upon which the

charge to be paid by the passenger for the hire of a vehicle

is indicated.

A "single-tariff" taximeter is one designed to calculate

farefe based on mileage at a single rate only.

A "multiple-tariff" taximeter is one so designed that it may be set to calculate fares based on mileage at any one of

two or more rates. A taximeter shall be considered to be "cleared" when it

is inoperative with respect to all fare registration, when no

figures indicating fare or extras are exposed to view, and when

all of the parts are in that position in which they are designed

to be when the vehicle to which the taximeter is or may be

attached is not engaged by a passenger.

A "money drop" is an increment of fare registration.

The "initial money drop" is the initial increment of fare

registration following the flag pull.
TAXIMETERS 31

The "flag" is the metal plate attached to the end of the

lever arm by means of which the operating condition of the

taximeter may be manually controlled.

Specifications.—1. Basis of Fare Calculation.—Taximeters shall be so designed and constructed as to calculate

the fare only upon one of the following bases

:

(a) Mileage traveled.

(&) Time elapsed.

(c) A combination of mileage traveled and time elapsed

such that when the taximeter is operable with respect to

fare registration, the fare-registering mechanism is actuated

by the mileage mechanism whenever the vehicle upon which

the taximeter is installed is in motion at such a speed that

the rate of mileage revenue per unit of time equals or exceeds

the time rate, and may be actuated by the time mechanism,

whenever the speed of the vehicle is less than this, or when

the vehicle is stopped. When constructed upon this principle, provision shall be made whereby the driver of the

vehicle may cause the clock mechanism to be operative or inoperative with respect to the fare-registering mechanism,

as the occasion may demand.

2. Character of Indications.—Taximeters shall be so designed and constructed that the following indications are shown upon the face:

(a) The condition of the taximeter, that is, whether it is inoperative or operative, and, if the latter, the character of

fare registration for which it is set. This specification shall

be construed to require (1) that while a taximeter is cleared,

the indication "Not registering/' "Vacant/' or an equivalent

expression shall appear; (2) that in the case of single-tariff

taximeters, while the taximeter is in condition for fare registration on any basis, the indication "Registering/' "Hired,"
32 NATIONAL BUREAU OF STANDARDS

or an equivalent expression shall appear; (3) that in the case

of multiple-tariff taximeters, while in the condition described in (2) preceding, the basis for the particular tariff for

which the taximeter is set shall be shown. In the case

of the lowest rate for which the taximeter is adjusted the

indication specified in (2) preceding shall be considered satisfactory; in the case of any higher rate the indication shall be

shown by such an expression as" 3 or more persons," etc.; and

(4) that while the taximeter is so set that the clock mechanism is inoperative with respect to fare registration, the

indication "Time not recording" or an equivalent expression shall appear, except when the taximeter is cleared. This

indication may replace the indication specified in (2) preceding, but shall be in addition to the indication specified in

(3) preceding for the higher rates on multiple-tariff taximeters.

(b) The accumulated fare. Theindications shall beidentified

by the word "Fare " or by an equivalent expression, and their

values shall be defined by suitable words or monetary signs.

(c) The extras. Taximeters are not required to be constructed so as to register charges for extras, but when so constructed the following shall apply: Extras shall never be

included in the fare registration, but shall always be indicated

as a separate item. They shall be identified by the word

"Extras" or by an equivalent expression, and their values

shall be defined by suitable words or monetary signs.

The indications required by this specification shall be displayed through, and shall be entirely protected by, glass

which shall be securely attached to the metal housing of the

taximeter, so that the indications will be protected by the

official seals. Note.—Whenever charges for extras are prohibited by legal authority, or whenever the assessment of extras has been discontinued by a

given taxicab operator, if the taximeters in use in the jurisdiction or by

the operator in question are constructed to register extras, the extras
TAXIMETERS 33

mechanism on such taximeters shall be rendered inoperable or all indications on the faces of the taximeters of charges for extras shall be effec- tively obscured by permanent means.

3. Obscuring of Indications.—Except as provided by the

"Note" of specification No. 2, and except when a taximeter

is cleared, indications of the amount of fare and extras registered shall never be obscured, and the apertures through

which such indications are read shall never be covered.

4. Readability of Indications.—All apertures through

which any indications or markings are viewed at any time

shall be of such location, size, and design that the indications

may be read with precision. This specification shall be

construed to require that in the case of drums or dials

designed to advance intermittently, but one indication

shall be exposed to view at one time, and that in the case of

graduated drums or dials designed to advance gradually

and continuously and to be read in combination with an

indicator, a sufficient number of graduations and figures

shall be exposed to view at all times readily to permit the

indications to be read correctly.

5. Statement of Rates.—All taximeters shall he marked

upon their faces to show the rates, both for mileage and time,

for which they are adjusted, and the schedule of extras when

such charges are recognized. This specification shall be construed to require a statement of the mileage and time rates for

the initial as well as for subsequent intervals whenever the rates are not uniform throughout. The words "Rate" "Rates,"

or "Rates of fare" shall precede the actual statement of the

rates, and the latter shall be self-explanatory and readily understandable by the ordinary passenger.

The marking required by this specification shall either be

of a permanent character, or shall be displayed through, and

shall be entirely protected by, glass securely attached to the
34 NATIONAL BUREAU OF STANDARDS

metal housing of the taximeter, so that the marking will he

protected by the official seals.

6. Marking of Change Gears.—All individual change

gears utilized in compensating for differences in tire diameters

shall be plainly marked to show the number of their teeth. 7. Lettering and Graduations.—All indications and

markings required under these specifications shall be of such

size, design, material, and location and shall be so applied or

affixed that they are definite and distinct and that they will

not tend easily to become obliterated or illegible.

8. Flag.—All taximeters shall be equipped with a flag.

The positions of the flag, corresponding to the different

conditions of a taximeter, shall be mechanically defined,

and displacement from any one of these positions shall be

sufficiently obstructed so that the accidental or inadvertent changing of the condition of the taximeter is improbable.

The flag shall be at its highest position when the taximeter

is cleared and in this position the whole of the flag shall be

above the level of the taximeter housing. Adequate provision

shall be made so that the attempted movement of the flag to an operating position immediately following its movement to

the cleared position shall automatically be so delayed that

the taximeter mechanism may come to complete rest in the

cleared condition before such subsequent movement is begun.

9. " Extras'' Knob or Handle.—The knob, handle,

or other means utilized to actuate the " extras" mechanism

shall be inoperative whenever the taximeter is in the cleared

condition; that is, whenever it is not in a condition to regis- ter fares.

10. Provision for Sealing.—Adequate provision shall

be made for sealing all taximeters, and in the case of complete

assemblies—that is, installations upon cabs of taximeters and
TAXIMETERS 35

the various gears and other parts required for service operation—adequate provision shall be made for sealing all of the

parts in place, in such manner that no adjustments, alterations, or replacements, affecting in any way the indications,

the time or mileage rates, or, in general, the accuracy of the

taximeters or the assemblies, can be made without mutilating

or destroying the seal or seals. 11. Visibility of Indications.—When mounted upon a cab a taximeter shall be so placed that its face is in plain

view of a passenger seated upon the rear seat of the cab.

Adequate lighting facilities shall be provided for so illuminating the face of the taximeter that the indications thereof

may be conveniently read by the passenger and the face

of the taximeter shall be so illuminated whenever the taximeter is in operation and artificial illumination is necessary

for the convenient reading of its indications.

12. Permanence.—Taximeters shall he of such design,

construction, and materials that they may reasonably be expected

to withstand ordinary usage without impairment of their

accuracy or the correct functioning of their operating and

indicating parts. This specification shall be construed to require that in the case of ratchets and pawls and similar combinations, wherever the accuracy or consistency of the indications of the taximeter would be affected by the wearing away or

the deformation of one or both of the cooperating parts, the

ratchets and pawls shall be fabricated of such material and

shall be hardened to such a degree and extent that the wear or deformation resulting from use will be reduced to a minimum.

13. Fraudulent Construction.—All taximeters and all mechanisms and devices designed to be attached thereto and

used in connection therewith shall be of such design and

construction and shall be so installed for use that they do

not facilitate the perpetration of fraud,
36 NATIONAL BUREAU OF STANDARDS

Tolerances.—Definitions.—A

" bench test" is a test of a

taximeter head alone, except that the gear box—that is, the

change gears designed to compensate for tires of different

sizes—may be attached.

A " wheel test" is a test of the entire taximeter assembly

when mounted upon a vehicle, the mechanism being actuated

by the mechanical revolution of the vehicle wheel while the

cab remains at rest. A "road test" is a test similar to a wheel test except that

the mechanism is actuated as a result of cab travel.

The "initial" mileage or time interval is the mileage or time interval corresponding to the initial money drop.

"Tolerance in deficiency" and "tolerance in excess" are the allowable errors in the directions of overregistration and

underregistration, respectively.

Values.—The tolerances to be allowed on all taximeters

shall be as follows:

L On Mileage Tests.

(a) On bench test.—With respect

to the nominal number of spindle revolutions, no tolerance in

deficiency and a tolerance in excess, of 2 per cent of the interval under test, with an added tolerance of 100 feet whenever

the initial interval is included in the interval under test.

(&) On wheel and road tests.—With respect to distance

computed or actually traveled, no tolerance in deficiency and

a tolerance in excess, of 4 per cent of the interval under test,

with an added tolerance of 100 feet whenever the initial

interval is included in the interval under test: Provided,

however, That on a road test if the vehicle tires are obviously

worn, a tolerance in deficiency, of 1 per cent shall be allowed.

Note.—In computing road results and calculating the values of change gears for the purpose of applying tolerances, the mean effective circumference of tire shall be used. This shall be determined upon a new tire of the size, kind, and make in use, inflated to the pressure recommended by the manufacturer, and mounted upon a vehicle,
LIQUID CAPACITY MEASURES 37

by causing the tire to describe several complete revolutions upon a smooth surface, rinding the average distance advanced per revolution,

and deducting from the result 1 per cent. 2. On Time Tests.

(a) On individual time intervals.—

A

tolerance of 3 seconds per minute (5 per cent) in deficiency

and a tolerance of 6 seconds per minute (10 per cent) in excess

:

Provided, however, That on the initial time interval the toler- ance in excess shall be 9 seconds per minute (15 per cent).

(&) On the average time interval (computed after excluding the initial interval).—No tolerance in deficiency and a

tolerance of 3 seconds per minute (5 per cent) in excess. LIQUID CAPACITY MEASURES

Specifications.—1. Liquid measures shall be made of metal,

glass, earthenware, enameled ware, composition, or similar

and suitable material, and shall be of sufficient strength and

rigidity to withstand ordinary usage without becoming bent,

indented, distorted, or otherwise damaged: Provided, however, That when the measure is made of iron or steel, or iron or

steel plated with tin, zinc, or copper, or is made oj copper, the

minimum thicknesses oj the metal shall he those given in the

following table:

Capacity of measure Minimumthickness if ofiron or steel or ofplated iron

or steel 1 Minimum

thickness if of copper

Inch Inch Over 1 gallon. __ 0. 016 0. 0S2

1 gallon. .OH . 028

3^2 gallon .014 . 028

1 quart .014 .028

1 pint or less . 010 . 020

i The following commercial tin plates will comply with these requirements: Over 1 gallon, 2XL; 1 gallon, H gallon, and 1 quart, IX; 1 pint or less, ICL.
38 NATIONAL BUKEAU OF STANDAKDS

2. Liquid measures of the customary system shall be of one of the following capacities only: One gallon, a multiple

of the gallon, or a binary submultiple of the gallon, that is, a measure obtained by dividing the gallon by the number 2

or by a power of the number 2: Provided, however, That

nothing in this specification shall be construed to prevent the

use of forms for ice cream, exclusively, in 5-pint and 3-pint

sizes, or bottles for milk or cream in the 3-pint size.

3. Liquid measures shall be so constructed that the capacity

is determined by a definite edge, plate, bar, or wire at or near

the top of the measure. When one of the last three forms is employed the capacity shall be determined to the lowest

portion of such plate, bar, or wire.

4. No subdivided liquid measures shall be allowed, and the

only reinforcing rings which may be used are those which are firmly attached to the outside of the measure and do not, by

indentations or in any other manner, show divisions or lines on the inside surface of the measure.

5. The capacity of the measure shall be conspicuously, legibly,

and permanently indicated on the side of the measure. This

shall be in combination with the word "Liquid" or the letters "Liq" in the case of measures in which the word "quart" or "pint" occurs. In the case of measures made of earthenware,

enameled ware, or composition, this marking shall be of a different color than the measure.

6. If a liquid measure is provided with a tap or spigot, the

construction shall be such that the measure may be completely emptied by the tap or spigot while it is standing upon

a level surface.

7. When a lip or rim, designed both to facilitate pouring

and to receive any overflow, is provided, the measure shall

be so constructed as to hold its full capacity exclusive of the

lip or rim, while it is standing upon a level surface.
GLASS GRADUATES 39

Tolerances.—The tolerances to be allowed in excess and

in deficiency on all liquid capacity measures shall be the

values shown in the following table : Provided, however, That

the manufacturers' tolerances or the tolerances to be allowed on all new liquid capacity measures shall be one-half of the

values given.

Capacity of measure

Tolerance In excess In deficiency Liquid Cubic Liquid Cubic ounces inches ounces inches 10 gallons 10 18. 0 5. 0 9. 0

5 gallons 6 11. 0 3. 0 5. 4

4 gallons r 4 7. 0 2. 0 3. 6

3 gallons ' 4 7. 0 2. 0 3. 6

2 gallons 2 3. 5 1. 0 1. 8 Drams

1 gallon 1 1. 8 4. 0 . 9 Drams Vi gallon 6 1. 4 3. 0 . 7

1 quart. 4 . 9 2. 0 . 5

1 pint 3 . 7 1. 5 . 3

Vz pint. 2 . 4 1. 0 . 2

1 gill 2 . 4 1. 0 . 2 GLASS GRADUATES

Specifications.1. Graduates shall be made to contain or

to deliver the indicated volume at 20° C. (68°F.). They shall

be legibly, conspicuously, and permanently marked to indicate

whether they are graduated to contain or to deliver.

2. Graduates shall be either cylindrical or conical in shape.

In the case of all cylindrical graduates the ratio oj length of the

graduated scale to the internal diameter shall not be less than

five to one. In the case of conical graduates the ratio of length

of the graduated scale to the internal diameter at the highest

graduation shall not be less than two to one, and at one-fourth of

the total capacity this ratio shall not be less than one to one.
40 NATIONAL BUREAU OF STANDARDS

3. Graduates shall be made of good quality glass, thoroughly annealed, clear, transparent, of uniform but not

excessive thickness, and free from bubbles and streaks.

4. Graduates shall be provided with a base at right angles

to the axis and of such a diameter that the graduate will stand

when placed on a surface making an angle of 25 per cent, or approximately 15°, with the horizontal.

5. All graduates shall be provided with pouring lips. 6. The graduation marks shall be perpendicular to the

axis and parallel to the base and to each other.

7. Main graduation marks are those indicating the principal subdivisions into which a graduate is divided, the value

of which should readily be ascertainable in order to facili- tate the reading of the graduate at any point on its scale.

All main graduation marks shall extend around the same

proportional part of the circumference of the graduate. All

graduation marks of this character shall be construed to be

main graduation marks. These graduations shall extend at

least one-half of the distance around the graduate: Provided,

however, That on duplex, or double-scale, graduates a clear space

shall be left between the ends of the main graduation marks on

the two scales, and this space, measured parallel to the graduation

marks, shall conform to the following values:

Circumference of graduate at the graduation marks

Distance be- tween ends

of graduation marks

Inch Up to 5 inches—.. _ _ 1/8-1/4

From 5 inches to 10 inches, inclusive 1/4-1/2

More than 10 inches. _ 8/8-5/8

Intermediate graduation marks are those which extend

around a smaller proportional part of the circumference of the
GLASS GRADUATES 41

graduate than do the main graduation marks, ana when these

are employed the graduations shall be varied in length in such

a manner that the scale may be conveniently read, but in no

case shall any graduation mark extend less than one-fourth of

the distance around the graduate.

8. Graduation marks shall be clear and distinct and uniform in character. They shall be etched or engraved, and

shall not exceed 0.015 inch (0.38 mm) in width. Blown or pressed graduation marks shall not be allowed.

9. The clear interval between the graduation marJcs shall not

be less than 0.04 inch (1 Tnm).

10. The value of the main graduation marks shall be

plainly designated, each number being placed either directly

upon or immediately above the graduation mark to which it refers, but the position of the numbers shall be consistent

throughout the graduated scale. If placed upon the graduation marks, the numbers shall be placed from the ends a suffi- cient distance to allow the ends to be used in making a setting.

Intermediate graduation marks shall not be numbered.

11. On all single-scale graduates, where the main graduation

marks do not completely encircle the graduate, the middle points

of the main graduation marks shall be directly opposite the lip.

On duplex, or double-scale, graduates the center of the clear

spaces between the ends of the main graduation marks, provided

for in specification 7, shall be approximately 90° from the lip.

Tolerances.—The tolerances to be allowed in excess or

deficiency on glass graduates marked "to contain" shall be

the values shown in the following tables ; the tolerances to be

allowed on graduates marked "to deliver" shall be 25 per

cent greater than the values given.

Note.—The tolerance to be used at any point on any graduate shall be determined by measuring the inside diameter of the graduate at the point under test and taking from the table the tolerance value

corresponding to this diameter.

112054°—29 4
42 NATIONAL BUREAU OF STANDARDS

Tolerance for Graduates of Various Diameters

Values Expressed in U. S. Customary Units Diameter Tolerance Diameter Tolerance Inches Sixteenths Drams Minims Inches Sixteenths Drams Minims

6 0. 6 2 4 32

7 . 8 2 5 34

8 1.0 2 6 36

9 1. 3 2 7 39

10 1. 6 2 8 41

11 2. 0

12 2. 5 2 9 44

13 3. 0 2 10 47

14 3. 5 2 11 49

15 4. 0 2 12 52

2 13 55 o 5

1 6 2 14 58

2 6 2 15 1 2

3 7 3 0 1 5 4 8 3 1 1 8

3 2 1 12

- 5 9

- V 10 3 3 1 15

- 7 11 3 4 1 18

3 12 3 5 1 21

- 9 14 3 1 24

3 7 1 27

- 10 15

1 11 16 3 8 1 31

12 17 3 9 1 34

13 19 3 10 1 38

14 21 3 11 1 41

3 12 1 44

1 15 22

2 0 24 3 13 1 47

2 1 26 3 14 1 51

2 2 28 3 15 1 55

2 3 30 4 0 2 0
GLASS GRADUATES 43

Tolerance for Graduates of Various Diameters

Values Expressed in Metric Units Diameter Tolerance ml 1 10_ . 0. 04

11 . 05

12 . 06

13 . 07

14 . 08

15 . 09

16 . 10

17 . 12 18 . 14

19 . 16 20 . 18 21 . 20

22 . 22

23 . 24

24 . 26

25 . 28

26 . 30

27 . 35

28 . 35

29 . 40

30 . 45

31 . 45

32 . 50

33 . 55

34 . 60

35 . 60

36 . 65

37 . 70

38 . 75

39 . 80

Diameter Tolerance

1 m

70 3. 2 71 3. 4

72 3. 5 73 3. 6

74 3. 7 75 3. 9 76_._ 4. 0

77 4. 1 78 4. 2 79 4. 4

80__ 4. 5 81 4. 6

82 4. 8

83 4. 9 84 5. 0 85 5. 1 86__ _ _ 5. 2 87 5. 4 88 5. 5 89 5. 6 90 5. 7

91__ 5. 9 92„ ___ 6. 0

93 6. 1 94 6. 2 95 6. 4

96 6. 5 97 6. 6 98 6. 8

99 6. 9 100 7. 1

Diameter Tolerance ml 1 40 0. 85

41 _ . 90

42 . 95

43 1. 00

44 1. 05

45 1. 10 46 1. 15 47 1. 25

48 1. 30

49 1. 35

50 1. 4

51 _ _ 1. 5 52 1. 6

53 1. 6

54 1. 7 55 1. 8

56 1. 9 57 2. 0

58 2, 0 59 2. 1 60__ _ 2. 2 61._ 2. 3 62 2. 4

63___ __ 2. 5

64__ 2. 6

65 2. 7 66 2. 8

67 2. 9 68_____ _ 3. 0

69 3. 1

1 The term milliliter, or "ml," is used herein to designate the one-thousandth part of the

liter. This unit is also commonly known as the cubic centimeter, or the "cc." The latter is not an accurate usage, as the units are not exactly equal, but the difference between them is of no consequence for the purposes of this table, and therefore they may be used interchangeably.
44 NATIONAL BUREAU OF STANDARDS

MILK BOTTLES

Specifications.—1. Bottles used foi* the sale of milk or cream shall be made only in sizes heretofore specified under

the heading " Liquid capacity measures/' and they shall

be made to contain their indicated capacities at a temperature of 20° C. (68° F.).

2. Each bottle shall have its capacity clearly blown or otherwise clearly and permanently marked in or on the side oj the

bottle, and in or on the side or bottom the name, initials, or trade-mark oj the manufacturer thereof.

3. Glass bottles with an inside diameter of not over 2

inches immediately below the cap seat or stopple shall hold

the correct capacity when filled to within one-fourth inch

of this cap seat or stopple; bottles with an inside diameter

of over this amount immediately below the cap seat or stopple shall hold the correct capacity when filled to within

one-eighth inch of this cap seat or stopple: Provided, however, That a larger distance shall be allowed below the cap

seat or stopple when the bottles are provided with a clearly

defined line blown or otherwise clearly and permanently

marked in or on the bottle, and extending at least halfway

around it, which indicates the correct capacity, and directly over, below, or beside this line, with the words "Fill to line" or a similar and suitable inscription clearly and permanently

marked in or on the bottle. The distance between the line

herein mentioned and the cap seat or stopple shall in no case exceed that given in the table below.
MILK BOTTLES 45

Capacity of bottle Maximum

distance allowable

Inches 2 quarts. _ 2

3 pints. _ 1 quart m 1 pint _ __ i piat - 5/8

1 gill 5/8

Tolerances.—The tolerances to be allowed in excess or

deficiency on bottles to be used in the sale of milk or cream

shall be as follows

:

(1) When a test comprises less than 25 bottles of the same

capacity and ownership, the tolerances shall be those given in

Table A below.

(2) When a test comprises 25 or more bottles of the

same capacity and ownership, the tolerances shall be applied

not only to the individual bottles but also to the average capacity of at least 25 such bottles, these to be taken at random

when the whole supply available is not tested. The error on

any individual bottle among those tested shall not exceed the

values shown in Table A below. The average error on the

bottles tested shall not exceed the values shown in Table B

below : Provided, however, That in the case of bottles already

in use, if the average error is greater than that above specified, then, if desired, all of the bottles of the particular size

and ownership in question may be treated as individual

measures, in which case all of these bottles shall be separately

tested, and the tolerances shown in Table C below shall be

applied.

Note.—To find the average error on a number of bottles, first add

all those errors which are in excess; then add all those errors which

are in deficiency; then subtract the smaller sum from the larger; and

finally divide this result by the total number of bottles tested.
46 NATIONAL BUREAU OF STANDARDS

Capacity of bottle

Table A,

tolerance on

individual

bottles

Table B,

tolerance on

average

capacityTable C, spec

individual b< use In excess

ial tolerance for

)ttles already in

In deficiency Drams Cubic

inches Drams Cubic

inch Drams Cubic

inches Drams Cubic

inch 2 quarts_ 6 I. 4 1. 5 0. 35 6 1. 4 3 0. 7

3 pints __ _ _ 5 1. 2 1. 25 . 29 5 1. 2 2. 5 . 6

1 quart 4 . 9 1. 0 . 23 4 . 9 2 . 5

1 pint. _ 3 . 7 . 75 . 17 3 .7 1. 5 . 3 3^ pint _- 2 . 5 . 5 . 12 2 . 5 1. 0 . 2

1 gill 2 . 5 . 5 . 12 2 . 5 1. 0 . 2 LUBRICATING-OIL BOTTLES

Note.—These specifications and tolerances are to be put into force and effect on January 1, 1929, and are to be nonretroactive. However,

after July 1, 1930, all bottles in use may be required to comply with

these specifications and tolerances. Specifications.—1. Bottles used for the sale of lubricating

oil shall he made of clear, uncolored glass and only in sizes

heretofore specified under the heading "Liquid capacity measures." They shall be made to contain their indicated capacities

at a temperature of 20° G. (68° F.), and they shall not be

subdivided.

2. The over-all heights of bottles of the various capacities shall

not be greater than the values shown in the following table:

Capacity of bottle Maximum height 1 2 quarts 12% inches.

1 quart- 10}/2 inches.

1 pint.. 8}4r inches.

1 Committee Note.—Bottles are now being developed and produced in which the bottle and the spout are integral; for instance, a metal top may be permanently attached to the

bottle, or the bottle may be so shaped as to include a glass spout. In such cases it seems

that compliance with these specifications will be substantially secured when the over-all height of the bottle and the permanently attached spout, or the over-all height of a bottle blown integral with the spout, does not exceed the height specified in this table, plus 6 inches which is the figure given in specification No. 5 as the allowable length of a detachable spout.
LUBRICATING-OIL BOTTLES 47

3. Each hottle shall have its capacity clearly blown or otherwise clearly and permanently marked in or on the side of the

bottle, and in or on the side or bottom the name, initials, or trade-mark of the manufacturer thereof.

4. Bottles shall be provided with a clearly defined graduation

line blown or otherwise clearly and permanently marked in or on the bottle, and extending at least halfway around it, which

indicates the correct capacity, and with the words "Fill to line ,} or a similar and suitable inscription clearly and permanently

marked in or on the bottle and clearly referable to this graduation line. This line shall in no case be more than 0.10 inch in

width and the bottom edge of the line shall define the top of the meniscus of the water which is used in the test of the bottle. This graduation line shall be placed so that it is at least one- fourth inch below the bottom of any metal top when this is screwed firmly into place. The capacity of that portion of the

bottle above the bottom of the graduation line shall be at least 3

cubic inches.

5. When a bottle is equipped with a spout, this shall be so constructed that free and unobstructed drainage is provided.

This specification shall be construed to require that there be an

effective air vent in the spout and no shoulder or other obstruction tending to result in a trapping of the liquid being delivered.

The spout shall not be over 6 inches in length measured from the

point of contact with the top of the bottle to the tip of the spout.

(See footnote to table in Spec. No. 2 above.)

Tolerances.

The tolerances to be allowed on all bottles used

for the sale of lubricating oils shall be in excess only and shall

be the values shown in the following table. There shall be no

tolerance allowed in deficiency.
48 NATIONAL BUREAU OF STANDARDS

Capacity of bottle

Tolerance Drams Cubic

inches

2 quarts

1 quart _

1 pint„„_

128

6

2. 7

1. 8

1. 4

LIQUID-MEASURING DEVICES

Definition.~A mechanically operated retail liquid-measuring device, hereinafter referred to as a liquid-measuring

device, is a mechanism or machine adapted to measure and

deliver liquid by volume, and which, on account of the

character of its primary indicating elements, is obviously

designed for unit deliveries of less than 50 gallons : Provided,

however, That for the purpose of these specifications and

tolerances, this definition is not to be construed to include

grease-measuring devices.

Specifications. —1 . Permanence. —All liquid-measuring

devices shall be of such design, construction, and materials that

they may reasonably be expected to withstands ordinary usage

without impairment of the accuracy of their measurement

or the correct functioning of their operating or indicating parts.

2. Plumb and Level Conditions.—All liquid-measuring

devices shall be so designed and constructed that they will be

in normal operating position when they are in level. All liquidmeasuring devices shall be installed plumb and level, and their

installation shall be of such strength and rigidity as to maintain

this condition.

3. Means to Determine Level.—Liquid-measuring devices, the indications or deliveries of which are changed by an

amount greater than one-half the tolerance allowed, when set in any position on a surface making an angle of 5 per cent
LIQUID-MEASURING DEVICES 49

or approximately 3° with the horizontal, shall be equipped with

suitable means by which the level can be determined and established, such as a two-way or a circular level, a plumb bob,

leveling lugs, etc. 4. Units of Delivery.—Liquid-measuring devices shall

have the following discharge capacities per stroJce or per cycle

of the primary indicating elements, and these only: 1 gallon, a multiple of the gallon, 2}/2 gallons, or a binary submultiple

of the gallon, that is, the quantity obtained by dividing the gallon

by the number 2 or a power of the number 2: Provided, however,

That a device may be constructed to deliver other amounts than

the above, corresponding to predetermined money values at a

definite price per gallon, but in such cases either the device

shall be so constructed thai the price per gallon at which it is

set at any time will be clearly indicated to the customer by

automatic means or this price shall be shown by means of a

sign conspicuously displayed on the device.

5. Device to Indicate When System is Properly

Filled.—All liquid-measuring devices other than those of the

visible type shall be equipped with a device which will indicate

whether or not the system is properly filled before a delivery

is begun. This specification shall be construed to prohibit a

check valve in the discharge line in such a position that the

partial emptying of the system would not be disclosed, but not

to prohibit a manually operated valve in the standpipe.

Note.—This specification shall not be put into force and effect prior to July 1, 1929.

6. Indication of Delivery.—All liquid-measuring devices shall be so designed and constructed that the initial zero condition and the amount delivered shall be clearly and

definitely indicated by automatic means, and the indication

of any delivery shall take place only when the full discharge

has, in fact, occurred: Provided, however, That the require-
50 NATIONAL BUREAU OF STANDARDS

ment that the full discharge shall have been completed before

registration shall not apply to the dribble flow caused by the

displacement of a piston rod during the return of a piston to

its initial position, when a clear statement conspicuous to the

customer and adjacent to the indicating means is placed on the

liquid-measuring device to the effect that the full amount can

not he delivered until the piston or the pointer or indicator has

teen returned to its initial position,

7. Sensitiveness.—All liquid-measuring devices shall be so designed and constructed that they can readily be operated

to deliver each quantity for which a graduation, stop, over- flow pipe, or other indicating means is provided, within the

tolerance on such amount hereinafter provided.

This specification shall be construed to require that in the case of all devices which have a graduated scale or dial or similar

indicating means which at some point or points or at all points

constitutes the sole or most sensitive means of determining the

amount of liquid discharged, the length on such scale or dial

equivalent to the tolerance at any graduation must be readily

appreciable when the character of the indicating element and its normal distance from and position in reference to the observer's

eye are taken into consideration, and in no case shall this length

be less than 0.04 inch. For example, if a device is designed

and constructed so that (1)1 gallon is the first graduation;

(2) there is no stop, overflow pipe, or other automatic means of

terminating the delivery; (3) the graduations are equally

spaced; and (4) if th>e cross section of the measuring chamber

is the same throughout its length, the minimum length on the

scale or dial shall be 8.1 inches per measured gallon, the maximum effective cross-sectional area of the measuring chamber

shall be 75 square inches, and, if cylindrical, the maximum

effective diameter shall be 9.75 inches. \ Note.—The second paragraph of the above specification was adopted

tentatively only.
LIQUID-MEASURING DEVICES 51

8. Constancy of Delivery.—The amounts delivered by

any liquid-measuring device shall not vary from the standard

by more than the tolerances hereinafter provided (1) irrespective of the speed at which the device is operated, except that

when operated considerably faster or slower than normal

speed of operation the tolerance shall be applied in deficiency

only—that is, the device shall not be deemed to be incorrect

by reason of the tolerance in excess being exceeded during

such unusual methods of operation—and (2) irrespective of

the time elapsing between operations, subject to the conditions of the special elapsed-time test described below.

A special elapsed-time test shall be made to determine

whether the device is satisfactory in respect to condition (2)

above. In order to comply with this test the condition of

the device shall be such that a period of nonuse of one hour

shall not result in an error on the first delivery of the device

after such period of nonuse greater than the appropriate

tolerance allowable on the smallest amount which the device is designed to deliver, this tolerance being selected according to whether the device is or is not a new device; and a

period of nonuse of 6 hours shall not result in an error on the

first delivery of the device after such period of nonuse greater

than 10 cubic inches, or in the case of a new device 5 cubic

inches. " Normal speed of operation" shall be construed to mean

that range of operating speeds which may reasonably be

employed in ordinary commercial usage ; in the case of meters

used for the purpose of determining the quantity of liquid

delivered to an individual purchaser, this shall mean operation within the limits of the discharge rates ordinarily developed under conditions of installation recommended or

specified by the manufacturer for the particular type of

meter under test, and all such meters shall he legibly marked

to show the maximum discharge rates under normal conditions
52 NATIONAL BUKEATJ OF STANDARDS

of installation and the minimum discharge rates and the maximum working pressures for which they are intended to he used:

Provided, however, That the value of the minimum rate shall not

be greater than 7 gallons per minute.

Note.—The italicized portion of the preceding paragraph shall not be put into force and effect prior to July 1, 1929. Notes.—In the special elapsed-time test described above, allowance

shall be made for errors due solely to a change in volume of the contained liquid, resulting from temperature variations alone, since an

error of this character is unavoidable in the case of volumetric measure- ments of this kind when the apparatus is standing unused. This change

in volume due to temperature variations is, however, small in amount for

all ordinary variations of temperature, amounting in the case of gasoline

to about 0.6 per cent for each 10° F. change of temperature, or about

1.1 per cent for each 10° C. change of temperature. In applying the elapsed-time test outlined above it is recommended

that the delivery be not made through a hose, since the amount of gasoline necessary to wet the inside of the hose will cause an additional

shortage in the delivery. All meters encountered in the field should be tested at the maximum

discharge rate developed under the conditions of installation actually

employed regardless of whether this rate exceeds or is less than the

maximum discharge rate marked on the meter, and also either at the

rate of 7 gallons per minute or at any lower discharge rate marked by

the manufacturer.

9. Indicating and Registering Parts.—Counters and

graduated scales and dials used on liquid-measuring devices

to tally sales and deliveries to individual purchasers or to

indicate the amount delivered when any portion of the cycle or stroke has been completed, shall be of such size and style

and shall be so located and disposed that they are clearly

visible to and readable by the customer from any position

which he may reasonably be expected to assume. The

graduations shall be of such character and arrangement that

the major ones are more prominent than and are clearly

distinguishable from the minor ones. In all types of liquid-
LIQUID-MEASUKING DEVICES 53

measuring devices ivMcli have a graduated scale which at some

point or points or at all points constitutes the sole or most

sensitive means oj determining the amount of liquid discharged,

the width of the graduation marks shall not exceed 0.04 inch.

10. Pointers and Indicators.—All pointers and indicators which when used in conjunction with a graduated

scale or dial indicate the amount of liquid discharged or the money value of the delivery at a predetermined price

per unit of volume, shall be so shaped that a correct and

accurate reading is given.

Pointers and indicators are required to he symmetrical about

the graduation lines at which they may stand: Provided, hwuoever, That in the case of pointers and indicators used in connection with straight scales having nonparallel graduation lines and

in respect to the nonhorizontal lines on such scales, this requirement shall he waived 'If the pointers and indicators are so designed and constructed that as the pointer or indicator approaches the correct indicating position in respect to any graduation line, only such portion of such graduation line as has not

yet heen reached hy the index of the pointer or indicator or hy a

horizontal line extended forward from the end thereof, shall he

exposed to view, and all other portions of such graduation line

adjacent to the index of the pointer or indicator shall he automatically obscured.

Pointers and indicators which when used in conjunction

with a graduated scale or dial constitute at some point or points

or at all points the sole or most sensitive means of determining

the amount of liquid discharged or the money value of the delivery

at a predetermined price per unit of volume, shall reach to the

finest graduation marks, and the width of the pointer or indicator, or of the end thereof, shall not he greater than the width

of such marks.

11. Parallax.—All liquid-measuring devices in which the accuracy of the readings of any indicating mechanism is affected
54 NATIONAL BUREAU OF STANDARDS

by parallax shall be so designed and constructed, as to reduce

to a minimum the errors due to this cause. This specification shall he construed to require that in the case of all devices which are equipped xoith a glass measuring

chamber and in which the quantities delivered are determined by

bringing the liquid surface into coincidence with indicators,

pointers, or graduations, which at some point or points or at all points constitute the sole or most sensitive means of determining

the amount of liquid discharged, such pointers, indicators, or graduations shall be located inside the glass measuring chamber

and not more than 1/16 inch from the surface thereof.

12. Graduated Scales.—When a liquid-measuring device

is provided with a graduated scale or dial, this shall be

riveted to its supports or otherwise permanently fixed in

position: Provided, however, That in the case of liquid-measuring devices of the gauge-glass type a sliding scale will be

permitted when the displacement of such scale is, by suitable

means, automatically prevented at all times when liquid is being discharged from the delivery outlet.

13. Numbering of Graduations.—Figures defining the

value of graduations shall be uniformly placed in reference to the graduation marks and shall be as close thereto as practicable,

but shall not be sq placed as to interfere with the accuracy of

reading. Such figures shall be in regular sequence; that is} sequences such as 5, 1, 2, 3, 1$, shall not be permitted.

14. Scales Reading in Opposite Directions.—The use on a liquid-measuring device of two graduated scales reading

in opposite directions and referable to the same indicating

means shall not be permitted.

15. Lettering and Graduations.—All markings, instructions, figures, and graduations required under these specifications

shall be of such size, design, material, and location, and shall
LIQUID-MEASUKING DEVICES 55

be so applied or affixed, that they will not tend easily to become

obliterated or illegible. 16. Return of Indicating Element to Zero.—All liquidmeasuring devices shall be so designed and constructed that

the indicating element used in tallying deliveries to individual purchasers is returnable readily to a definite and clear zero reading before the next delivery is begun.

17. Positive Stops.—When the stops or other stroke-limiting devices on a liquid-measuring device are subject to direct

pressure or impact in the operation of the device, such stops

shall be of such construction that the permanence and security

of their positions is provided for by a positive, nonfrictional

engagement of the parts whose relative motions are to be prevented. Such stops shall be so designed and constructed that

adjustment within the prescribed tolerances can be made.

18. Positioning of Stop Mechanism.—All liquid-measuring devices designed to deliver two or more different predetermined amounts by bringing into operation different stops or other means of defining the delivery, shall be so designed and

constructed that the position for the proper setting of each

stop is definitely and accurately defined, inadvertent displacement from this position is obstructed, and the delivery

for which the device is set at any time is clearly and conspicuously indicated.

19. Provision for Sealing.—All devices adapted to be

altered for adjusting or correcting the delivery of a liquidmeasuring device, or for changing the maximum delivery rate of a meter when this change tends to affect the accuracy of the

deliveries, shall be of such construction that they can be sealed,

either separately or together, in such a manner that the position

of none of them can be changed without destroying the seal or

seals: Provided, however, That this shall not apply to such

devices as alter the deliveries to conform to different prices per
56 NATIONAL BUREAU OF STANDARDS

gallon on such a liquid-measuring device as is described in the

proviso of specification No. 4- Note.—In this specification the words "or for changing the maximum delivery rate of a meter when this change tends to affect the

accuracy of the deliveries" are to be put into force and effect not prior to July 1, 1929. 20. Use of Adjustments.—No adjustment of the delivery

of a defined-stroke liquid-measuring device shall be permitted

except that intended to produce a piston displacement per

cycle of 231 cubic inches per indicated gallon of delivery.

Adjustments of piston displacement to correct for leaks, slippage, excessive length of pipe line, or other defects of the

device or of the installation shall not be permitted.

21. Assurance of Complete Delivery.—All liquidmeasuring devices shall be so designed and constructed as to furnish assurance that all measured liquid which is apparently

being delivered from that delivery outlet which is being employed in any particular operation of the liquid-measuring

device, is actually being delivered so long as there is any

liquid passing through this delivery outlet.

This specification is to be construed to require that all valves in the supply line intended to prevent the reversal of

flow of the liquid shall be of such design and construction

that their closure is automatically effected in the use of the

device and that when two or more delivery outlets for the

liquid are provided a delivery made through one delivery outlet shall not affect the subsequent delivery through any other

delivery outlet. It is further to be construed that either (1)

there shall be no means provided by which any of the

measured liquid can be diverted from the measuring chamber

or the discharge line to the supply tank or elsewhere during

the period that liquid is flowing from the delivery outlet

apparently in sole use, or (2) if there be any means whatever
LIQUID-MEASURING DEVICES 57

by which an incomplete delivery or any diversion of measured

liquid can be accomplished or made, then the device must

be so designed and constructed that such fact will automatically become an immediately obvious one to anyone observing

the operation of the device.

21a. Auxiliary Visible Indicating Devices.—Whenever a liquid-measuring device of the visible type is so designed and

constructed that measured liquid continues to pass through the discharge valve for an appreciable time (3 seconds or more) after

the liquid has disappeared from sight in the glass measuring

chamber, then the device shall be equipped with an auxiliary

visible indicating device, adjacent to the discharge valve and so constructed that it mill indicate after the completion of the delivery when any portion of the measured liquid has not been

discharged through such valve at the time of the closing thereof:

Provided, however, That in the case of any nominal delivery

which is such that it does not cause the liquid to disappear from

the chamber, the time interval mentioned above shall be measured

from the time that the liquid apparently ceases to fall in such

chamber.

Such auxiliary visible indicating device shall be so designed

and constructed and so located and disposed that its indication

is conspicuous and that, during the operation of the liquidmeasuring device, it is clearly visible to and readable by the customer. Whenever an auxiliary visible indicating device designed; to indicate drainage of liquid and/or completeness of

delivery shall be employed, whether or not it is required by the

terms of this specification, it shall comply with all the above

requirements.

Note.—This specification is to be put into force and effect not prior

to July 1, 1929. 21b. Time Allowed for Completion of Delivery.—

All liquid-measuring devices shall be so designed and con112054°—29——5
58 NATIONAL BUREAU OF STANDARDS

structed, or so calibrated, that on a nominal delivery of 5 gallons they will deliver this quantity into the discharge line on

the delivery side of the discharge valve, within the tolerance for

devices in use, within a period of 10 seconds after the main

flow of liquid has ceased.

The main flow shall be construed to cease , in the case of a

device of the piston type, at the completion of the upward stroJce of the piston, and in the case of a device of the visible type, at

the time of the disappearance of the liquid in the glass measuring chamber: Provided, however, That in the case of any

nominal delivery which is such that it does not cause the liquid

to disappear from the chamber, the time that the liquid apparently ceases to fall in such chamber shall be used in lieu of the

time of the disappearance of the liquid: And provided further, That in the case of any liquid-measuring device equipped

with an auxiliary visible indicating device such as is described

in specification No. 21a, any conspicuous change of indication in this device, such as a sudden drop in the level of the

liquid, occurring after the major portion of the delivery has

been completed, shall be used in lieu of either of the indications

mentioned above.

All tests and calibrations shall be made on the basis outlined

above, that is, the delivery valve shall be closed, or the operation

of the liquid-measuring device otherwise discontinued, at the

termination of the period of time mentioned above, and the

amount which shall then have been delivered shall be taken as

the full delivery of the device.

Note.—This specification shall be limited to apply only to liquidmeasuring devices when used in the sale of motor fuels. Note.—This specification is to be put into force and effect not

prior to July 1, 1929. Committee Note.—Since upon review following the Twenty-first National Conference the Committee on Specifications and Tolerances

is convinced that the foregoing specification in its present form does
LIQUID-MEASURING DEVICES 59

not accomplish the purpose for which it was designed, the committee

proposes for consideration at this time:

First, that the first paragraph of this specification be amended to read as follows: All liquid-measuring devices shall be so designed and constructed, or so

calibrated, that they will deliver into the discharge line on the delivery side of the discharge valve, within the tolerances hereinafter provided, any nominal quantity which they are designed to deliver, within a period of 10 seconds

after the main flow of liquid has ceased. Second, that the following words be added at the end of the third

paragraph of the specification: for the nominal quantity being delivered. It is the present intention of the committee to propose these amendments to the Twenty-second National Conference which is to be held

in May or June, 1929. This material is included here so that timely

notice may be given to interested parties.

22. Valves in Discharge Line.—No liquid-measuring

device shall be equipped with a discharge valve at the

extremity of the hose or elsewhere in the hose line unless

the device is so designed and constructed either that it must be operated with the hose full of liquid at all times

or that the fact that the hose is drained will automatically

become an immediately obvious one to anyone observing

the operation of the device. In case the discharge valve is so positioned, any other valve not immediately adjacent

thereto, in any portion of the discharge line leading to

this outlet, shall be so designed and constructed that it can only be closed off in one Qf the following ways: (1) By

the use of some tool or device which is outside of and entirely separate from the measuring device itself, such as a wrench, screw driver, etc., but not an adjusting pin; or

(2) by the destruction of a seal. In case the latter construction is used means shall be provided so that a seal of the

usual lead-and-wire type may readily be employed to seal

the valve open and the manufacturer shall furnish his
60 NATIONAL BUREAU OF STANDARDS

device with the valve sealed open; there shall be a metal

tag or plate attached to the device adjacent to this valve

handle clearly stating that the device should not be used

unless the valve handle is secured by a seal. This specification is not to be construed as allowing a

discharge valve in the hose in the case of devices in which,

without the fact being obvious to the observer, the hose

or any part thereof can be drained of liquid after the

actual mechanical operation of the mechanism of the liquidmeasuring device is discontinued, in any way except as fol- lows: (1) By means of the mechanically operated valve, or

(2) by delivering from the measuring device more than the

full measuring capacity thereof during the actual mechanical

operation of the mechanism thereof.

23. Drainage of Discharge Line. —All liquid-measuring devices shall be so constructed and installed that they

will provide for the complete and rapid drainage, to a definite

and uniform level, of the liquid contained in the hose or

outlet pipe, and will not permit a siphoning or a continuous

trickle of liquid from the discharge outlet after the operation

of the mechanism is discontinued.

This specification will be construed to require that if hose

is used its inlet end shall be at least 5 feet above the normal

level upon which the receiving vehicle or vessel stands and

the liquid-measuring device shall be equipped with an automatic vacuum breaker or equivalent means to insure the

complete and rapid drainage of the hose, that is required by

the above. The hose shall be properly reinforced and shall

be of such length and stiffness that no movable portion thereof

will be readily disposed in such a way as to tend to retain

liquid after the operation of the device is completed: Provided, however, That this specification shall not be construed

to apply to devices which, under the terms of specification
LIQUID-MEASURING DEVICES 61

No. 22, may be equipped with two shut-off valves or cocks

and are to be operated with the hose full of liquid at all times.

24. Height of Suction Lift.—No defined-stroke, pistontype, liquid-measuring device shall be so installed as to work under a total suction head sufficient to cause vaporization of the liquid for which it is used under the highest temperature and lowest barometric pressure likely to occur.

25. Limitation of Use.—Liquid-measuring devices which

will not give correct results except when used with liquids having

particular properties—as, for example, high viscosity—shall

he conspicuously, clearly, and permanently marked to indicate

this limitation. Such wording may take the form, " Not suitable for gasoline or light oils," " Use only for molasses or heavy oils," or "For viscous liquids only."

26. Computing Charts.—When liquid-measuring devices are equipped with money-value computing charts these shall be

made in accordance with one of the following principles:

(a) If the device is so designed and constructed that it purports to compute for one or for a series of unit prices the total price for every delivery within the range of the device, then the

device shall be equipped with a value pointer or indicator and

value graduation marks; the value graduation marks shall be

correctly placed; and in any position which the indicator or pointer and the chart may assume there shall be exposed to view a sufficient number of value figures and graduations to permit

the value indications of the device to be read correctly. The

value graduations shall not exceed 1 cent at all prices per gallon up to and including 30 cents. At any higher price per

gallon the value graduations shall not exceed 2 cents: Provided,

however, That nothing in the above shall be construed to prevent

the placing of a special value graduation to represent each

5-cent interval. These special graduations may take the form
62 National bureau of standards

of dots, staggered graduations, or similar forms. They shall

he so placed that their meaning and value may be clearly understood, hut they shall not he placed in the space between the regular

graduations.

(b) If the device is so designed and constructed that it purports automatically to compute only for deliveries corresponding

to a definite series of quantity graduations, then one of the

following alternatives shall be complied with: (1) There shall

be a value computation for each quantity graduation throughout

the range of the device; or {2) no value indications may be exposed

to view except at such times that the device registers a quantity

indication for which a correct value indication is provided;

or (3) each value graduation or each column or row of such

graduations shall be clearly and conspicuously marked with

the quantity graduation to which the value corresponds a,nd

the device shall be marked with the character and limitations

of the computations made. All money values corresponding

to definite quantity graduations must be mathematically correct except as follows: If the mathematically correct amount includes a fractional part of a cent, the fraction shall be dropped if it is

less than one-half, but if the fraction is one-half or more the

next higher cent may be shown.

27. Fraudulent Construction.—All liquid-measuringdevices and all devices designed to be attached thereto and

used in connection therewith shall be of such design and

construction that they do not facilitate the perpetration of

fraud.

General Note.—Conflict of Laws and Regulations.—In the above

specifications certain items appear which may conflict in certain jurisdictions with present State or local laws or ordinances or regulations

of State or local fire marshals or boards of safety. In such cases of

conflict an attempt should be made by the weights and measures offi- cials to harmonize the two codes, and in the meanwhile it may be found

necessary to suspend the enforcement of such specifications.
GREASE-MEASURING DEVICES 63

Tolerances.—Except in special tests described above the

tolerances to be allowed in excess or deficiency on all liquidmeasuring devices shall be the values shown in the following

table: Provided, however, That the manufacturers' tolerances or the tolerances on all new liquid-measuring devices shall

be one-half of the values given: And provided further, That

these latter tolerances shall also be applied to all devices

which are being retested after having been found incorrect

and subsequently adjusted or repaired.

Delivery Tolerance

Gallons l/2 or less.

1 L _

Cubic inches 2

3

• 4

56

78

910

1112

2

34

5678

9 . 10

For deliveries of over 10 gallons add 1 cubic inch per

indicated gallon.

GREASE-MEASURING DEVICES

Note.—The following code of specifications and tolerances for grease-measuring devices was adopted tentatively by the Twentyfirst National Conference on Weights and Measures, May 24, 1928. In accordance with the usual conference procedure this will come up

for review and final action at the meeting of the conference to be held

in 1929. The Bureau of Standards recommends that this code be not put into force and effect by the States prior to final action thereon by

the conference.
64 NATIONAL BUREAU OF STANDARDS

Definition.—A mechanically operated grease measuring

and dispensing device, hereinafter referred to as a greasemeasuring device, is a mechanism or machine adapted to measure and deliver grease or transmission oil by volume.

This definition is not to be construed to include devices

which are obviously designed and intended solely for highpressure lubrication of bearings and similar parts.

Specifications.—1. Permanence.—All grease-measuring devices shall be of such design, construction, and materials that

they may reasonably be expected to withstand ordinary usage

without impairment of the accuracy of their measurement, or

the correct functioning of their operating or indicating parts.

2. Units of Delivery.—Grease-measuring devices shall

have the following discharge capacities per stroke or per cycle

of the primary indicating elements, and these only: 1 pint, a multiple of the pint, or a binary submultiple of the pint,

that is, the quantity obtained by dividing the pint by the number

2 or a power of the number 2.

3. Indication of Delivery.—All grease-measuring devices shall be so designed and constructed that the initial zero condition and the amount delivered in terms of liquid measure shall be clearly and definitely indicated by automatic means, and the indication of any delivery shall take

place only when the full discharge has in fact occurred.

4. Sensitiveness.—All grease-measuring devices shall be so designed and constructed that they can readily be operated to deliver each quantity for which a graduation, stop, or other

indicating means is provided, within the tolerance on such amount

hereinafter provided, and whenever any scale or dial is at some

point or points or at all points the sole or most sensitive means

of determining the amount of lubricant discharged, a volume of

1 pint shall be represented on such scale or dial by a length of

not less than 1 inch.
GREASE-MEASURING DEVICES 65

5. Constancy of Delivery.—The amounts delivered by

any grease-measuring device shall not vary from the standard

by more than the tolerances hereinafter provided (1)

irrespective of the speed at which the device is operated,

except that in the case of devices operated by air pressure

when operated at an air pressure lower than the minimum

pressure specified by the manufacturer, the tolerance shall

be applied in deficiency only—that is, the device shall not

be deemed to be incorrect by reason of the tolerance in excess being exceeded during such method of operation—and

(2) irrespective of the time elapsing between operations.

In the case of all devices operated by air pressure there shall be

legibly marked on the dial oj the air-pressure gauge, by special

graduations or otherwise, the maximum and minimum working pressures recommended by the manufacturer.

6. Indicating and Registering Parts.—Counters and

graduated scales and dials used on grease-measuring devices

to tally sales and deliveries to individual purchasers or to indicate the amount delivered when any portion of the cycle

or stroke has been completed, shall be of such size and style

and shall be so located and disposed that they may be easily

read. The graduations shall be of such character and arrangement that the major ones are more prominent than and are

clearly distinguishable from the minor ones. In all types of

grease-measuring devices which utilize a graduated scale or

dial to indicate the amount of lubricant discharged, the width of

the graduation marks shall not exceed 0.04 inch.

7. Pointers and Indicators.—All pointers and indicators which when used in conjunction with a graduated scale or

dial indicate the amount of lubricant discharged shall be so shaped that a correct and accurate indication is given. Such

pointers and indicators are required to be symmetrical about the graduation lines at which they may stand and shall reach to the
66 NATIONAL BUREAU OF STANDARDS

finest graduation marks; the width of the end of the pointer or indicator shall not be greater than the width of such marks.

8. Parallax.—All grease-measuring devices in which the

accuracy of the readings of any indicating mechanism is affected

by parallax shall be so designed and constructed as to reduce

to a minimum the errors due to this cause.

9. Graduated Scales.—When a grease-measuring device

is provided with a graduated scale or dial, this shall be riveted or otherwise permanently attached to its supports.

10. Numbering of Graduations.—Figures defining the

value of graduations shall be uniformly placed in reference to the

graduation marks and shall be as close thereto as practicable, but

shall not be so placed as to interfere with the accuracy of reading.

11. Lettering and Graduations.—All markings, instructions, figures, and graduations required under these specifications shall be of such size, design, material, and location, and

shall be so applied or affixed, that they will not tend easily to become obliterated or illegible. 12. Movement of Indicating Element.—All greasemeasuring devices shall be so designed and constructed that the

indicating element used in tallying deliveries to individual purchasers shall only be susceptible of forward movement by the

mechanical operation of the device itself. The indicating element

shall be returnable readily to a definite and clear zero indication

before the next delivery is begun. Means shall be provided to prevent the indicating element from being returned beyond the zero indication.

13. Positive Stops.—When stops or other stroke-limiting

devices are employed on a grease-measuring device and these are subject to direct pressure or impact in the operation of

the device, such stops shall be of such construction that the per- manence and security of their positions is provided for by a

positive, nonfrictional engagement of the parts whose relative
GREASE-MEASURING DEVICES 67

motions are to be prevented. Such stops shall be so designed

and constructed that adjustment within the prescribed tolerances can be made.

14. Positioning of Stop Mechanism.—All grease-measuring devices designed to deliver two or more different predetermined amounts by bringing into operation different stops or

other means of defining the delivery, shall be so designed and constructed that the position for the proper setting of each stop is definitely and accurately defined, inadvertent displacement from

this position is obstructed, and the delivery for which the device

is set at any time is clearly and conspicuously indicated.

15. Provision for Sealing.—AU devices adapted to be

altered for adjusting or correcting the delivery of a grease-measuring device shall be of such construction that they can be sealed,

either separately or together, in such a manner that the position

of none of them can be changed without destroying the seal or

seals. 16. Use of Adjustments.—No adjustment of the delivery

of a defined-stroke grease-measuring device shall be permitted except that intended to produce a piston displacement per cycle of 28.875 cubic inches per indicated pint of

delivery. Adjustments of piston displacement to correct for

leaks, slippage, or other defects shall not be permitted.

17. Assurance of Complete Delivery.—All greasemeasuring devices shall be so designed and constructed that

there shall be no means provided by which any of the measured lubricant can be diverted from the measuring chamber

or the discharge line to the supply tank or elsewhere during

the period of operation of the device. All valves in the supply

line intended to prevent the reversal of flow of the lubricant

shall be of such design and construction that their closure is automatically effected in the use of the device.
68 NATIONAL BUREAU OF STANDARDS

18. Limitation op Use.—Grease-measuring devices which

will not give correct results except when used with lubricants

having particular properties shall be conspicuously, clearly, and

permanently marked to indicate this limitation.

19. Fraudulent Construction.—All grease-measuring

devices and all devices designed to be attached thereto and

used in connection therewith shall be of such design and construction that they do not facilitate the perpetration of

fraud.

Tolerances.—Except under special conditions as described

in specification No. 5, the tolerances to be allowed in excess or deficiency on all grease-measuring devices shall be 1}£

cubic inches (about 5/8 liquid ounce) on a delivery of 1 pinfc or less; for deliveries of more than 1 pint add 1 cubic inch

(about 1/2 liquid ounce) per indicated pint: Provided, however, That the manufacturers' tolerances or the tolerances on

all new grease-measuring devices shall be one-half of the values

given: And provided further, That these latter tolerances

shall also be applied to all devices which are being retested

after having been found incorrect and subsequently adjusted

or repaired.

VEHICLE TANKS

[When used as Measures]

Notes.—The following specifications and tolerances shall apply to

vehicle tanks and their accessory piping, valves, etc., in those cases in which the tanks or the compartments thereof are used or to be used as measures to determine the amount of liquid delivered, and such use

shall be permitted only when these specifications and tolerances are complied with.

If a tank is damaged in any way (as from collision, etc.), or if repairs

which might in any way affect the accuracy of measurement are made,

such tank shall not again be used as a measure until inspected and,

if deemed necessary, tested, by the weights and measures official. In determining or checking the capacity of tanks, water is recom- mended as a testing medium. In general, petroleum products are not
VEHICLE TANKS 69

recommended because the change in volume due to temperature vari- ations is large, and evaporation during the test may result in serious inaccuracies in the calibration. If the conditions are such that the use

of a petroleum product seems necessary, a neutral oil of high boiling

point should be selected, and great care exercised to eliminate the inac- curacies mentioned or to reduce them to a minimum.

Definition.—A vehicle tank, hereinafter referred to as a

" tank," shall, for the purpose of these specifications and toler- ances, mean a container, which may or may not be subdivided

into two or more compartments, mounted upon a wagon or automobile truck and used for the delivery of liquids. The

term "compartment" shall mean the entire tank whenever

the tank is not subdivided; otherwise it shall mean any one

of those subdivided portions of the tank which is designed

to hold liquid.

Specifications.—1. Permanence.—All tanks and all indicators, piping, valves, etc., attached thereto and used in connection

therewith shall be oj such design, construction, and material that

they may reasonably be expected to withstand ordinary usage

without impairment oj the accuracy of measurement.

2. Indicators.—An indicator shall be provided within the

fill opening of each compartment, which shall be located approximately mAdway between the ends oj the compartment. The indicator shall be so designed that it will clearly, distinctly, and unmistakably dejine the height to which the compartment must be

jilled in order to contain its marked capacity. Ij this indicator

is adjustable it shall be so constructed that it can be sealed in

such a manner that its position can not be changed without destroying or mutilating the seal.

3. Expansion Space.—The indicator shall be so positioned

that when a compartment is jilled to the indicator there will re- main an expansion space oj not less than 0.75 per cent oj the

nominal capacity oj the compartment.
70 NATIONAL BUREAU OF STANDARDS

4. Venting Means.—Each compartment shall be provided with suitable venting means to prevent the formation

of air pockets by permitting the escape of air from all parts of

the compartment designed to be filled with liquid and to permit the influx of air to the compartment during the process

of delivery.

5. Provision for Complete Delivery.—Each tank, and

all delivery piping attached thereto and used in connection

therewith, shall be so designed and constructed and shall be

so mounted upon the vehicle that when this is standing upon

a level surface complete delivery may be made from any compartment through the delivery faucets or valves whether

other compartments are full or empty.

6. Piping.—When emergency valves designed to close the

discharge outlets from compartments are provided, the capacities of such compartments shall be construed as including the

capacity of the piping leading therefrom, and such emergency

valves shall always be open when compartments are being

filled or their capacities are being checked.

7. Marking of Capacity.—Each compartment of a tank

shall be plainly and conspicuously marked with a designating

letter or figure, and each delivery faucet or valve shall be corre- spondingly marked to indicate the compartment of which it

is the outlet. In addition, the tank shall be plainly and conspicuously marked to show the capacity, to the nearest half

gallon, of each compartment and such marking shall indicate

that the capacities given are measured to the indicators provided. This latter marking shall he placed adjacent to thefaucets

or valves.

8. Lettering and Graduations.—All markings, figures,

and graduations required under these specifications shall, be
VEHICLE TANKS 71

of such size, design, material, and location, and shall be so applied or affixed, that they will not tend easily to become

obliterated or illegible.

9. Fraudulent Construction.—All tanks and all devices

designed to be attached thereto and used in connection therewith shall be of such design and construction that they do

not facilitate the perpetration of fraud.

Tolerances.—The tolerance to be allowed in excess or

deficiency on all vehicle tank compartments which are being

tested by the weights and measures official for the first time,

to verify the accuracy of a capacity marked by a manufacturer or user, shall be the values shown in the column headed

"On first test" in the following table. The tolerance to be

allowed in excess or deficiency on all subsequent tests made

by the official, to verify the accuracy of a marked capacity,

shall be the values shown in the column headed "On subsequent test." These tolerances are to be applied to the differ- ence between the actual result of the calibration and the

marked capacity of the compartment. Whenever the result

of a calibration indicates that the marked capacity of a compartment is not correct within the tolerance to be applied,

if the capacity of the compartment is adjustable, then the

marking shall be changed in accordance with the provisions of

specification No. 7, or the result of the calibration shall be

taken as the basis of an adjustment and the adjustment shall

be so made that the capacity of the compartment agrees as nearly as may be with such marked capacity; if the capacity

of the compartment can not be adjusted to agree with the

marked capacity, then the marking shall be changed in ac- cordance with the provisions of specification No. 7.
72 NATIONAL BUBEAU OF STANDABDS

Capacity of compartment Tolerance From— Up to and

including—

On first

tevSt On subse- quent test

Gallons 175

325

475

575

725

875

975

1, 125

1, 325

Gallons 175

325

475

575

725

875

975

1, 125

1, 325

1, 500

Gallons 1/2

1/2

3/4

1m

m

m2

3

Gallons 1/2

12

34

5

6

DRY CAPACITY MEASURES

Specifications.—1. Dry capacity measures, and baskets

used as dry measures, shall be made of metal, well-dried

wood, or composition, or similar and suitable material,

and shall be of sufficient strength and rigidity to withstand ordinary usage without becoming materially warped,

bent, dented, distorted, or otherwise damaged.

2. Diy measures, and baskets used as dry measures when such are allowed by the other specifications, shall be

of one of the following capacities only: 1 bushel, a multiple of the bushel, or a binary submultiple of the bushel,

that is, a measure obtained by dividing the bushel by the

number 2 or by a power of the number 2. 3. The capacity of all dry measures, and baslcets used as dry measures, shall he conspicuously, legibly, and permanently indicated on the side of the measure. This shall be in

combination with the word "Dry" in the case of measures in

which the word "quart" or "pint" occurs. The letters shall
DKY CAPACITY MEASURES 73

be at least one-half inch high and one-quarter inch wide on

measures having a capacity of 1 peck or less and at least 1 inch high and one-half inch wide on those having a capacity

of one-half bushel or more.

4. All dry measures having a capacity of one-half bushel

or less shall be cylindrical or conical in shape. If of the

latter shape, the top diameter shall be greater than the

bottom diameter, but never by an amount exceeding 10 per

cent of the latter. In no case shall the bottom diameter ex- ceed the top diameter.

5. The bottoms of all dry measures shall be perpendicular

to the axis of the measure and shall be flat, or when made of

metal may be slightly corrugated when such corrugations aid

in strengthening the measure. Such corrugations, when

employed, shall be parallel or radial straight lines only.

6. Wooden dry measures having a capacity of more than

1 pint shall have a metal band firmly attached around the top.

All metal dry measures shall be adequately reinforced around

the top.

7. Dry measures, and baskets used as dry measures, having a capacity of 1 bushel or more shall be equipped with

handles.

8. Baskets shall not be used as dry measures when having

a capacity of less than one-half bushel.

9. Dry measures, and baskets used as dry measures,

shall be of such construction that the capacity is determined by the top rim of the measure, and no subdivided measures or baskets shall be allowed.

10. Dry measures shall not be double-ended; that is, have the bottom set part way up into the measure so that

both ends may be utilized as measures, either of the same

or of different capacities.

11. Dry measures, and baskets used as dry measures,

shall not have adjustable or movable bottoms.

112054°—29——

G
74 NATIONAL BtFBEJAU OF STANDABDS

12. The minimum diameters of dry measures of various

capacities shall conform to the following table:

Capacity of measure Minimum

diameter

Inches 3^ bushel _ _ _ uk

1 peck 10%

3^ peck _ _ _ _ sy2 2 quarts. 6%

1 quart.. _ 5%

1 pint- 4

Tolerances.—The tolerances to be allowed in excess and

in deficiency on dry capacity measures, and baskets used as dry capacity measures, shall be the values shown in the fol- lowing table: Provided, however, That the manufacturers'

tolerances or the tolerances to be allowed on all new dry

capacity measures and baskets used as dry capacity measures

shall be one-half of the values given:

Tolerance Capacity of measure

In excess In deficiency

Cubic inches Cubic inches

1 bushel... 50. 0 25. 0

bushel 30. 0 15. 0

1 peck _ 16. 0 8. 0

peck _ __ 10. 0 5.0

2 quarts— 5.0 2.5

1 quart-. __ _____ 3.0 1.5

1 pint- 2.0 1. 0

pint. . 1.0 .5

J£ pint- __ .5 . 3
BERRY BASKETS OR BOXES 75

BERRY BASKETS OR BOXES

Specifications.—1. Baskets or boxes for berries or small

fruits, of a capacity of 1 dry quart or less, shall be of one of

the following sizes: 1 quart, 1 pint, or one-half pint, dry

measure.

Tolerances.—The tolerances to be allowed in excess and

in deficiency on baskets or boxes for berries or small fruits,

constructed of wood, shall be the values shown in the following table:

Tolerance Capacity of basket In excess In deficiency

Cubic inches Cubic inches

1 quart__ _ _ _ _ 3 1. 5

1 pint 2 1. 0

3^ pint. _ _ 1 . 5 The tolerances to be allowed in excess and in deficiency on

baskets or boxes for berries or small fruits, constructed of

pasteboard or fiber, shall be the values shown in the following

table

:

Tolerance Capacity of measure

In excess In deficiency

Cubic inches Cubic inches 1 quart. . . 2. 0 1. 0

1 pint- I. 0 . 5 le pint . 5 . 25
76 NATIONAL BUREAU OF STANDARDS

SCALES

General Specifications.—1. The nominal or rated capacity

of a scale is the largest weight indication which can be obtained by the use of all its reading or recording elements in

combination.

When one reading or recording element of the scale is designed for auxiliary use only, such as a small bar and

poise intended for use in determining weights intermediate

between two graduations on the principal bar of the beam,

the weight value of this reading or recording element is not

to be included in the sum, provided that it does not exceed

2 per cent of the sum of the weight values of the remaining

reading or recording elements. (Thus, a platform scale with

the principal bar of the beam graduated to 100,000 pounds

by 1,000-pound subdivisions and with an auxiliary bar

graduated to 1,000 pounds by 20-pound subdivisions is to

be considered as having a nominal capacity of 100,000

pounds.)

When a scale is designed for use with removable weights

and these are furnished with the scale, the amount which

these represent when used on the scale shall be included in

the sum of the weight values of the reading elements. When

the scale is designed for use with removable weights but

these are not furnished with the scale, the amount which

those represent on the scale that are usually furnished with

the scale when weights are included shall be included in the

sum of the weight values of the reading elements.

2. All scales not equipped with a beam or reading jace

graduated to the full capacity of the scale, or those not equipped

with a graduated beam or reading face, which, taken in connection with another graduated beam or beams or with a graduated runner indicates the capacity of the scale, shall have the
SCALES—GENERAL SPECIFICATIONS 77

nominal or rated capacity conspicuously, clearly, and permanently marked upon them.

2a. No scale shall be used in weighing loads greater than

its nominal or rated capacity.

3. All scales shall be of such construction that they will

support a load of maximum capacity without undue bending

or straining of the parts.

3a. The construction of all scales shall be such that when

the beam is displaced to the full extent allowed by the construction of the scale, it will return to its normal position.

4. All pivots shall be firmly secured in or to the levers.

5. All Tcnife-edges shall he of hardened and tempered steel,

except that agate may be used jor special classes of scales when

specifically permitted by the specifications therefor. They shall

be sharp and bear throughout the entire length of the parts

designed to be in contact.

6. All bearings shall be smooth and at least as hard as the

Tcnife-edges. For scales of more than 5,000 pounds capacity,

the bearings shall be made of hardened and tempered steel. {The term "bearing" used in this specification refers to the

entire surface which is designed to be in contact with a Jcnife- edge or with a point bearing.)

7. When plates or caps are used to limit the longitudinal

motion of a Jcnife-edge, the parts of such plates or caps which

are liable to come into contact with the Jcnife-edge shall be

smooth and at least as hard as the Jcnife-edge. The parts of

the Jcnife-edge liable to come into contact with these plates or caps shall be so formed that the friction between them is reduced

to a minimum.

8. If a scale has a nose iron, the proper position of this, as determined by the factory sealing operation, shall be clearly,

accurately, and permanently indicated. A nose iron is defined

as a slidably-mounted, manually-adjustable pivot assembly

designed for changing the multiplication of a lever.
78 NATIONAL BUREAU OF STANDARDS

9. If the scale has interchangeable or reversible parts, these

shall be so constructed that their interchange or reversal

will not affect the balance or the accuracy of the instrument.

10. No scale shall be equipped with a scoop counterbalanced by a removable poise or weight.

11. When the scale is equipped with a permanently at- tached device intended to counterbalance the weight of a removable scoop, this device shall clearly indicate on the

customers' side of the scale whether the scoop should be

on or off the scale.

12. The graduations on all beams shall consist of lines, or notches, or of a combination of these. All lines shall be

uniform in spacing and parallel to each other. All notches

shall be evenly cut, and the lines formed by the intersection

of the sloping planes of their sides shall be uniform in spacing

and parallel to each other. When a combination of lines

and notches is employed, the lines shall be properly placed

with reference to the notches so as to indicate the value of

each notch clearly and correctly.

12a. The graduations on all beams and reading faces shall

be clear and distinct and in no case shall their width be less than 0.008 inch.

12b. The clear interval between the graduations on all beams

shall not be less than 0.04 inch.

13. Each main weight graduation shall be so marked as to indicate the weight represented by the poise or other indi- cator. Main graduations are to be construed as those the

value of which should be readily ascertainable in order to

facilitate reading at any point.

14. Shoulders or stops shall be provided on all beams to prevent the poise traveling and remaining back of the zero graduation.

15. The adjusting material in all poises shall be securely

inclosed and firmly fixed in position. If of lead or other
SCALES—GENERAL SPECIFICATIONS 79

material softer than brass, it shall not be in contact with the

beam.

16. Poises shall be so constructed that no part can be

easily detached, and if equipped with a set screw this shall

not be removable.

17. Poises on notched beams shall be provided with a pawl or other device, so constructed as to cause the poises

to be seated into a definite and correct position in each notch,

wherever in the notch the pawl or other device is placed, and

to be held there firmly and without appreciable movement.

18. The bearing edge of a hanging poise shall be hard and

sharp, and shall be so formed as to allow the poise to swing

freely in the notches of the beam.

19. Reading edges or indicators of poises shall be sharply

defined, and all reading edges shall be parallel to the graduations on the beam.

20. Poises shall not be readily detachable from the beam:

Provided, however, That this specification shall not apply to

poises on steelyards unless there is a zero graduation on the

beam.

21. When a scale is equipped with a beam, the position or

oscillation of which is used to indicate the balance of the

scale, the normal position of this beam shall be horizontal,

and it shall have equal play above and below the normal

horizontal position.

22. No scale shall be so constructed that the beam is unstable or accelerating.

28. Scale pans in which fish or other wet commodities are placed when weighed shall he so constructed as to provide for

drainage.

23a. When tests are being made with both increasing and

decreasing loads on any scale, the indications on all increasing

loads shall be within the usual tolerances provided, and also at any stage of the test the range between corresponding
80 NATIONAL BUREAU OF STANDARDS

observations for increasing and decreasing loads shall not be

greater than the sum of the tolerances in excess and in deficiency for the load in question. This specification is to be

construed as applying only to automatic-indicating scales.

23b. All devices intended to increase or decrease the capacity

of a scale by the addition or subtraction of a weight or weights

shall operate properly irrespective of the speed with which they are manipulated.

24. All scales shall be of such design and construction that

they are reasonably permanent in their adjustment and will

repeat their weight indications correctly, and do not facili- tate the perpetration of fraud.

25. All scales shall be maintained in balance.

A scale is in balance, as the term is used herein, when it correctly gives a weight indication of zero when there is no

load on the platform, plate, or other load-receiving element.

A lever scale of the nonautomatic type not having an

indicator and a graduated scale or arc is in balance when the

beam comes to rest at, or oscillates through approximately

equal arcs above and below, the center of the trig-loop when

one is provided; or a position midway between other stops

when these are provided; or a horizontal position when no

trig-loop or other stops are provided.

A scale of the nonautomatic type having an indicator and

a graduated scale or arc is in balance when the indicator

comes to rest at, or oscillates through progressively smaller

arcs about, a definite and clear zero graduation.

A scale of the automatic-indicating type—that is, one having a reading face or dial—is in balance when the indicator

comes to rest at a definite and clear zero graduation.

Sensibility Reciprocal (SR).—The term " sensibility reciprocal" or "SR" hereinafter referred to is defined as the

weight required to move the position of equilibrium of the
SCALES—GENERAL SPECIFICATIONS 81

beam, pan, pointer, or other indicating device of a scale a

definite amount at the capacity or at any lesser load.

In scales provided with a beam and trig-loop, the SR is the weight required to be placed upon the platform to turn

the beam from a horizontal position of equilibrium in the

middle of the trip-loop to a position of equilibrium at the

top of the loop. The SR may be determined by subtracting

the weight instead of adding it, thereby causing the beam to assume a position of equilibrium at the bottom of the loop; or indirectly, by moving the sliding poise on the beam the

required amount in either direction, to obtain the specified

change in the position of equilibrium of the beam; or by

adding or subtracting small weights to or from the counterpoise until the specified change is obtained, and determining

the equivalent of the small weights used in terms of weight on the platform.

In the case of equal-arm scales and scales with a single

pan or plate above, or hanging from, the beam, which are not provided with a pointer moving over a graduated arc or scale, the SR is the amount of weight required on the pan

or plate to cause it to move from its position of equilibrium,

when the scale is in balance, to a position of equilibrium at

the limit of its motion.

In the case of scales provided with a single indicator and

a graduated scale or arc, one of which oscillates with reference

to the other to form a convenient means for determining the

position of equilibrium of the beam, and which does not of

itself directly indicate in terms of weight, the SR is the weight

required to cause a change in the position of rest of the pointer

equal to one division of the graduated scale or arc. In the case of scales equipped with two indicators which

move in opposite directions and oscillate with reference to each other to form a convenient means for determining the
82 NATIONAL BUREAU OF STANDARDS

position of equilibrium of the beam, the SR is the weight

required to cause a separation of the indicators of 0.04 inch,

measured in the direction of their movement.

Note.—The two preceding paragraphs are limited to apply only

to cream-test or butterfat-test scales and apothecaries' prescription

scales, but they are included here for the sake of completeness of the definition. The SR does not apply to reading faces or dials which indicate directly in terms of weight, but no such reading face or dial which is purely auxiliary to the scale mechanism

such as one, for instance, which may or may not be employed

in the determination of weight—shall be construed to exempt

a scale from the SR requirement when this face or dial is detached.

Note.—The effect of friction on a scale is to make possible a variation of the load on the pan, plate, or platform without any corre- sponding change in the indication. The value of the SR which is determined with the effect of friction present will, therefore, be in error by a variable amount. However, in making tests this error must be

neglected.

PLATFORM SCALES

[Including Counter Platform Scales]

Definitions.—A platform scale is a scale having a loadreceiving platform carried on multiplying levers which transmit the load to the beam or other reading element, such platform having four or more lines of support comprised in bearings which rest directly upon knife-edges in the multiplying

levers.

A counter platform scale is a scale of the above type

which is especially adapted on account of its compactness,

light weight, moderate capacity, and arrangement of parts,

for use upon a counter or table. Within the meaning of this
PLATFORM SCALES 83

definition, a platform scale is a counter platform scale when

it conforms to both of the following:

(1) Its weighing capacity is not more than 400 pounds.

(2) Its beam or other reading element is located at an

elevation sufficiently low in relation to the weighing platform

to be accessible and easily read when the scale is used upon

a table or counter.

Specifications.—1. The foundations of all built-in scales

shall be firm and substantial.

2. Platform scales having an outside frame around the

platform shall be equipped with means for centering and

checking the platform. These shall cause the platform

bearings to return to their normal line of contact on the

knife-edges when the platform is displaced to the full extent

allowed and also shall prevent the platform bearings from

such a displacement that the centering will not take place.

The above results may be obtained by any proper means that

will not introduce excessive friction and will not cause binding when the parts have been so caused to return to their

normal weighing positions.

3. Platform scales shall be so constructed that there is sufficient clearance between the platform and the frame to allow for any expansion due to weather effects. Sufficient

clearance shall also be provided to prevent the live parts of

the scale from binding on account of an ordinary accumulation of dirt or other ordinary causes. A wagon scale should have at least 12 feet of straight

driveway on either end of the scale in the same plane as the

platform.

5. Platforms and levers shall be of sufficiently rigid construction that the degree of deflection under the maximum

load will not endanger the accuracy of the scale.

6. If a scale is equipped with a relieving device, this

shall be so constructed that when the beam is balanced and
84 NATIONAL BUREAU OF STANDARDS

the device is used to relieve it and engage it again, one or more times, the former balance will again be assumed by the

beam.

7. When corner platform loops are removable, each shall be so marked or shaped as to identify it with its proper corner.

7a. The maximum value of the minimum graduations of

the graduated beams of counter platform scales used in the

sale of food stuffs at retail shall be 1 ounce: Provided, however, That this shall not apply to scales used exclusively in

the sale of vegetables.

8. All devices for adjusting the balance of a counter platform scale shall be of such construction that they are operative or accessible only by the use of some tool or device which

is outside of and entirely separate from the movable mechanism of the scale itself, such as a screw driver, wrench, etc., but not an adjusting pin.

9. All devices for adjusting the level of a counter platform

scale shall be of such construction that they are operative or

accessible only by the use of some tool or device which is outside of and entirely separate from the leveling devices,

such as a screw driver, wrench, etc., but not an adjusting pin.

9a. Counter platform scales whose weight indications are changed by an amount greater than one-half the tolerance allowed, when set in any position on a surface making an angle

of 5 per cent or approximately 8° with the horizontal, shall be

equipped with a device which will indicate when the scale is

level, and in no case shall any pendulum operating the scale

be considered a leveling device. The scale shall be rebalanced

at zero each time its position is altered during the test contemplated by this specification.

10. All platform scales, except track scales, shall be so constructed that when a load consisting of test weights repre-
PLATFORM SCALES 85

senting one-half or more than one-half of the capacity of the

scale, and not exceeding such capacity, is placed so that its center of gravity lies over the points designated by circles

in diagram No. 1, the error at each point shall not exceed the

tolerance allowed for the load employed. If a load equal to one-quarter of the capacity is used, this shall be placed so that its center of gravity lies directly over the platform bearings designated by the circles in diagram No. 2, and the errors

shall not exceed those indicated above.

Diagram No. 1 © ©

© ©

Diagram No. 2 11. Any device for altering the sensibility of a scale shall

be so limited in its adjustment that the beam can not be made

unstable by the manipulation of the device.
86 NATIONAL BUREAU OF STANDARDS

12. The minimum travel of the beam in the trig-loop shall

conform to the following table:

Distance from beam fulcrum to trig-loop Minimum

travel of beam in

trig-loop

Under 12 inches _ _ _ Inch 0.4

. 5

. 7

. 9

Over 12 inches, including 20 inches Over 20 inches, including Jfi inches Over 40 inches13. All weighing beams shall be so marked and graduated and all poises on these beams shall be so constructed

that the weight corresponding to any position of the poise can be read directly on the beam. This condition shall be

fulfilled whether or not a registering or stamping device is used.

14. When not modified by the above and in so far as they

are applicable, the following specifications shall also apply;

general for scales; those for spring scales relating to automatic-indicating elements, when the scale is so equipped

(except that graduations need not be equally spaced); and

also those under any heading hereafter when the scale is so constructed as to fall within the definition under such heading.

Sensibility Reciprocal (SR).—The maximum SR allowable on all platform scales, except counter platform scales, shall

be the value of two of the minimum graduations on the beam,

at the capacity of the scale or at any lesser load: Provided,

however, That the manufacturers' maximum SR or the maximum SR on all new platform scales, except counter platform

scales, shall be the value of one of the minimum graduations on the beam at the capacity or at any lesser load.

The maximum SRs for counter platform scales are given hereafter under the heading "Counter scales.
PLATFOEM SCALES 87

(The term " sensibility reciprocal" or "SR" means the

weight required to move the position of equilibrium of the

beam, pan, pointer, or other indicating device of a scale a

definite amount. In scales provided with a beam and

trig-loop the SR is the weight required to be placed upon

the platform to turn the beam from a horizontal position

of equilibrium in the middle of the trig-loop to a position

of equilibrium at the top of the loop. The SR may be determined by subtracting the weight instead of adding it, thereby

causing the beam to assume a position of equilibrium at the

bottom of the loop; or indirectly, by moving the sliding

poise on the beam the required amount in either direction,

to obtain the specified change in the position of equilibrium

of the beam; or by adding or subtracting small weights to or from the counterpoise until the specified change is obtained,

and determining the equivalent of the small weights used

in terms of weight on the platform.)

Tolerances.—The tolerances to be allowed in excess or

deficiency on all platform scales, except counter platform

scales and large-capacity automatic-indicating scales, shall be

the values shown in the following table : Provided, however,

That the manufacturers' tolerances or the tolerances on all new platform scales, except counter platform scales and

large-capacity automatic-indicating scales, shall be one-half

of the values given : And provided further, That these toler- ances on all these platform scales shall in no case be less than

the value of one of the minimum graduations on the beam,

except that the manufacturers' tolerances or the tolerances on new apparatus shall in no case be less than the value of

one-half of one of the minimum graduations on the beam.

The tolerances for counter platform scales are given hereafter under the heading " Counter scales/'
NATIONAL BUREAU OF STANDARDS

Load

Tolerance, Class A Tolerance, Class B

On ratio On beamor reading

face On ratio On beam

or reading

face Pounds Ounces Ounces Ounces Pounds 50 1/2 1

i no I 2 200 £t At 240 0 o 300 3 6

400 4 8 500 5 10 10

600 6 12 12 iH

Pounds Pounds 800 ___ _ _ 8 1 1 2 1,000 8 1 1 2 1,200. _ 10 m m 234

1,500 12 w% 3 1,800 1 A. 1 zx

Pounds o nnn i & £

A

/fejOUU _ £>Y2 D

a nnn 2 4 4 8

f\ nnn 3 6 6 12 8,000 4 8 8 16

i1U,UUU n nnn s? D

i n i n /U

i o nnn 5 12 12 24

10,UuU_ 8 16 16 32

20.000 10 20 20 40

24,000_ 12 24 24 43

1 in nnn 15 30 30 60

20 40 40 80

80 000 40 80 80 160

100,000 - 50 100 100 200

160,000 . 80 160 160 320

200,000 100 200 200 400

300,000 150 300 300 600

400,000 200 400 400 800
PLATFORM SCALES 89

Explanation of Preceding Table.—" Class A" scales include

the following: Scales of the portable platform type; and also

scales of the dormant or built-in type which are installed

inside of a building having side walls and roof which protect

the scale from weather effects and from sudden changes of

temperature.

" Class B" scales include the following: Scales of the rail- road track, autotruck, and wagon types; and also scales of

the dormant or built-in type which are not installed inside

of a building having side walls and roof, and which are exposed to weather effects and sudden changes of temperature.

Note.—The latter effect, since it causes the condensation of moisture on the scale parts, often has as serious results on the condition of the

scale as have weather effects. The columns with the heading " Tolerance on ratio" refer to the error in the ratio or multiplying power of scales with

which counterpoise weights are used.

The columns with the heading " Tolerance on beam or reading face" refer to those parts of scales not requiring the use of removable weights; for example, a beam.

The column with the heading "Load" refers to the amount

of weight on the platform of the scale. Application of Tolerances to Railroad Track Scales.—In

the case of railroad track scales designed and used for weighing ordinary freight traffic, when the test load consists of a one-truck test car, the largest algebraic mean of any two

errors found for different positions of the test truck shall not

exceed the tolerance corresponding to the test load used:

Provided, however, That no two errors shall be selected cor- responding to positions of the test truck closer together than ( the distance between similar points on adjacent spans. The

tolerance given in the table is not to be applied to the error found for a single position of the test load. (The largest

112054°—29 7
90 NATIONAL BUREAU OF STANDARDS

algebraic mean of any two errors may be defined as one-half

of the largest plus ( + ) or minus ( — ) sum that can be obtained

by adding any two errors, such as two plus errors, two minus

errors, a numerically large plus error and a numerically small

minus error, or a numerically large minus error and a numerically small plus error.)

In order that the largest algebraic mean of any two errors, which represents the maximum error of freight-car weighing,

may not differ appreciably from the true amount, a test car having a wheel base not exceeding 7 feet should be used.

LARGE-CAPACITY AUTOMATIC-INDICATING SCALES

Definition.—A large-capacity automatic-indicating scale is a scale, other than of the counter scale type, in which is embodied or to which is attached a self-acting mechanism, the

capacity of which may be equal to or less than the total

capacity of the scale, through the agency of which the indicated or recorded weights of variable loads may be obtained.

This definition is not to be construed to include scales which

automatically weigh out commodities in predetermined drafts,

such as automatic grain hopper scales, packaging scales, etc. Notes.—The following tolerances are not intended to be applied

strictly to scales already in use. 8 These tolerances shall not be applied to railroad track scales, not- withstanding that automatic-indicating devices are embodied in or attached to such scales. Tolerances.—The tolerances to be allowed in excess or

deficiency for tests at increasing loads 9 on large-capacity

s For a discussion of this matter, see committee report, p. 132, Report of the SixteenthAnnual

Conference on Weights and Measures, Miscellaneous Publications of the Bureau of Standards No. 55.

6 In the case of tests at decreasing loads specification No. 23a under the heading "Scales: General specifications," applies, See p. 79.
AUTOMATIC-INDICATING SCALES 91

automatic-indicating scales shall be the values shown in the

appropriate column in the tolerance table under the heading

"Platform scales " (see p. 88): Provided, however, That the

tolerances on the dial or reading face shall in no case be less than the value of one of the minimum graduations on the

dial or reading face, or one five-hundredth of the capacity

of the dial or reading face, whichever is less, except that on

such of these scales as have a minimum graduation of 1 pound or more on the dial or reading face such tolerance

shall not be less than 1 pound. The tolerances on any beam

or beams with which the scales may be equipped shall be

the same as those specified above, except in cases where the

value of the minimum graduation on any such beam is less than that of the minimum graduation on the dial or reading

face, or one five-hundredth of the capacity thereof, whichever determines the minimum tolerance on the dial or reading face, in which cases the minimum tolerance on any

such beam shall be the minimum graduation on any beam

with which the scale may be equipped.

The minimum tolerance to be allowed on the ratio or the

multiplying power of the scale shall be the same as the

minimum tolerance allowed on the beam: And provided

further, That the manufacturers' tolerances or the tolerances on all new large-capacity automatic-indicating scales shall be

one-half of the values specified above.

The tolerances to be allowed on large-capacity automaticindicating scales used exclusively in determining weights for

the sole purpose of fixing charges for the transportation of

freight shall be twice those specified above.
92 NATIONAL BUREAU OF STANDARDS

WHEEL-LOAD WEIGHERS

NOTE.—Wheel-load weighers are intended solely for official use

in the enforcement of traffic or highway laws. When sealed by the

weights and measures official they are to be sealed for the above

purpose only; they are never to be allowed in commercial use. Definition.—Wheel-load weighers shall, for the purpose of

these tolerances, mean portable devices designed for determining the axle loads of loaded trucks on highways.

Tolerances.—The tolerance to be allowed in excess or

deficiency on wheel-load weighers shall be 5 per cent of the

load applied: Provided, however, That the manufacturers'

tolerance or the tolerance on all new devices shall be 3 per cent,

in excess or deficiency, of the load applied: And provided

further, That this latter tolerance shall also be applied to all devices which are being retested after having been found

incorrect and subsequently adjusted or repaired. When the

devices are tested in pairs, the above tolerances shall be

applied to the sum of the indications of the two devices and

both shall be approved or condemned upon the sum of their

indications; in this case each of the pair of machines shall be

appropriately marked to identify the pair tested together.

COUNTER SCALES

Definition.—A counter scale is a scale of any type which

is especially adapted on account of its compactness, light

weight, moderate capacity, and arrangement of parts, for use upon a counter or table. However, those types embraced in the definitions of platform (including counter platform), spring, computing, cream-test, and prescription scales are considered under specific headings; the specifications

given here apply to the first three classes, but only when

applicable and not modified by the specifications therefor.
COUNTER SCALES 93

Specifications.—1. Bearings shall be so shaped that when

the beam or levers are displaced in any manner the knifeedges will return to their proper lines of contact. (The

term " bearing " as used in this specification is defined as that part of the scale designed to be in contact with the

knife-edge.)

2. All loose material used for adjusting the balance of a

scale shall be securely inclosed.

3. All devices for adjusting the balance of a counter scale

shall be of such construction that they are operative or

accessible only by the use of some tool or device which is outside of and entirely separate from the movable mechanism

of the scale itself, such as a screw driver, wrench, etc., but

not an adjusting pin.

4. All devices for adjusting the level of a counter scale

shall be of such construction that they are operative or

accessible only by the use of some tool or device which is outside of and entirely separate from the leveling devices, such

as a screw driver, wrench, etc., but not an adjusting pin.

5. Counter scales whose weight indications are changed by an amount greater than one-half the tolerance allowed, when set in any position on a surface making an angle of 5 per cent or approximately 3° with the horizontal, shall he equipped with a

device which will indicate when the scale is level, and in no

case shall any pendulum operating the scale be considered a

leveling device. The scale shall be rebalanced at zero each

time its position is altered during the test contemplated by this

specification.

6. In the case of equal-arm scales, either with stabilized

pans or plates—that is, those above the beam—or with suspended
94 NATIONAL BUREAU OF STANDARDS

pans or plates, the minimum fall or drop of the pans or plates

jrom their highest point shall he as follows:

Capacity Minimum

fall Inch Four pounds and below - 0.35

From 4 pounds, including 12 pounds—

.5

From 12 pounds, including 26 pounds . 75

Over 26 pounds 1. 0

7. In the case of counter scales having unequal arms or having a compound lever system, and equipped with a graduated beam which is not provided at or near its end

with a trig-loop or graduated scale or arc or other suitable

reference interval or point for establishing the proper

position of balance of the beam, the beam shall have a minimum total angular play of 8 per cent or approximately 5°. (The angular motion of the beam in terms of

per cent may be obtained by dividing the total fall or drop

of the beam at its end by the distance from the fulcrum to

the end of the beam and multiplying this quotient by 100.)

In case such scales are provided with a trig-loop or graduated scale or arc or other suitable reference interval or

point, the minimum total movement of the beam at such

point shall be 0.4 inch if the distance from the beam fulcrum to the reference means is 12 inches or less and 0.5

inch if the distance is over 12 inches.

8. Scales of such construction that any weight or weights

which are not visible can he added so as to affect the indications of the scale shall he equipped with a device which will

plainly indicate on the customers' side of the scale when the

weight or weights have heen added and the value which it or they represent on the scale.

9. On scales of the equal-arm type with stabilized pans

that is, pans above the beam—the under connections and a
COUNTER SCALES 95

line connecting the outer knife-edges in the beam shall

form a parallelogram. These under connections shall be

straight and work freety.

10. All scales shall be so constructed that when a weight

whose body has approximately equal diameter and height

and which represents one-half of the capacity of the scale

is shifted in any direction on the weight plate or on the

commodity plate, pan, or scoop to a point one-half the

distance between the center and edge of the weight plate or the commodity plate, pan, or scoop, the additional

resulting error in the weight indication, due to this cause

alone, shall not exceed the tolerance allowed at the load

in question given in the column headed " Tolerance on parts

requiring employment of removable weights": Provided,

however, That in this test the edge of the weight shall not

be made to project over the edge of the weight plate or the

commodity plate, pan, or scoop.

10a. The maximum value of the minimum graduations

of the graduated beams of counter scales used in the sale

of foodstuffs at retail shall be 1 ounce: Provided, however, That this shall not apply to scales used exclusively

in the sale of vegetables.

11. In the case of counter scales equipped with an indicator and a reading face or dial, such parts shall conform

to all the specifications applicable to them, given under

the heading " Spring scales," except that the graduations

are not required to be equally spaced.

12. All counter scales shall be maintained in level. 13. When not modified by the above, the specifications

given under the heading "Scales: General specifications"

shall apply to counter scales in so far as they are applicable.

Sensibility Reciprocal (SR).—The maximum SRs allowable

for counter scales shall be the values given in the table

below, at the capacity or at any lesser load, with the excep-
96 NATIONAL BUREAU OF STANDARDS

tion that when the maximum SR herein given is a larger value

than that represented by two of the minimum graduations on any beam with which the scale may be equipped, the

latter value shall be applied and used as the maximum SR

at the capacity or at any lesser load: Provided, however,

That the manufacturers' maximum SRs or the maximum

SRs on all new counter scales shall be one-half of the values

given in the table unless this value is greater than one

of the minimum graduations on the beam, in which case

this latter value shall be used.

(The term " sensibility reciprocal" or "SR" means the

weight required to move the position of equilibrium of the

beam, pan, pointer, or other indicating device of a scale a

definite amount. In the case of equal-arm scales and scales

with a single pan or plate above, or hanging from, the beam,

which are not provided with a pointer moving over a graduated scale or arc, the SR is the amount of weight required on

the pan or plate to cause it to move from its position of

equilibrium, when the scale is in balance, to a position of

equilibrium at the limit of its motion.)

Capacity

Maximum

sensibility reciprocal allowable Capacity

Maximum

sensibility reciprocal allowable Pounds Ounces Pounds Ounces

1 1/8

1/8

1/4

1/4

1/4

24. _ _ 1 2 25 1 4 30___ . 1 5 40 m

6 50 m

8 1/2

1/2

1/2

60

10 75 2

12 90

15 3/4

3/4

100 _ 3 20
COUNTER SCALES 97

Tolerances.—Except on the special tests described above,

the tolerances to be allowed in excess or deficiency on counter

scales shall be the values shown in the following table:

Provided, however, That the manufacturers 9 tolerances or the tolerances to be allowed on new counter scales shall

be one-half of the values given: And provided further, That

the tolerance on counter scales at any load shall in no case be less than one-half of the SR of the scale at the load in

question; and when the scale has a reading face or dial, the

tolerance shall in no case be less than one-fourth of the

minimum graduation on the reading face or dial, except that on new scales it shall in no case be less than one-eighth of

such minimum graduation.

Load

Tolerance on parts requiring employ- ment of removable

weights

Tolerance on beam or reading

face Load

Tolerance on parts requiring employ- ment of removable

weights

Tolerance on beam or reading

face

Pounds

1 Ounce 1/16

1/16

1/8

1/8

1/8 1/4

1/4

1/4

5/16

5/16

5/16

3/8

3/8

3/8

Ounce 1/16

1/8

3/16

3/16

3/16

3/8

3/8

3/8

1/2 1/2 1/2 1/2

1/2 5/8

Pound* 40

Ounces 7/16

1/2

5/8

3/4

7/8

1

Ounces 5/8

3/4

1 2 50

4 60

5 75 1 6 90

2

8 100_

10 150 m 12 200 2 3

15 240

2V2 3

4

16 250 4

20 300

24 350 33^2 5 25 400 4 6

30
98 NATIONAL BUREAU OF STANDARDS

SUSPENSION SCALES OF THE LEVER TYPE

Definition.—Suspension scales of the lever type are lever

scales designed and adapted to be hung from or attached to some support above and outside of the structure of the scale

itself, and which are not included within other classes herein

defined. This class shall include steelyards, butchers' meat

beams, suspension abattoir scales, crane scales, overhead

tramway scales, suspension creamery scales, suspension pendulum scales, and the like.

Specifications and Tolerances.—Suspension scales of the

lever type having a capacity of more than 400 pounds shall

be subject to the same specifications, in so far as these are

applicable, and the same SRs and tolerances as platform scales.

Suspension scales of the lever type having a capacity of 400

pounds or less shall be subject to the same specifications, in

so far as these are applicable, and the same SRs and toler- ances as counter scales. In the case of suspension scales of

the lever type equipped with an indicator and a reading face or dial, such parts shall conform to all the specifications

applicable to them-, given under the heading " Spring scales/'

except that the graduations are not required to be equally

spaced.

SPRING SCALES

Definition.—A spring scale is a scale in which the weight

indications depend upon the change of shape or of dimensions

of an elastic body or system of such bodies : Provided, however,

That scales in which metallic bands or strips are employed

for the primary purpose of fulfilling the functions of knifeedges and bearings shall not be considered spring scales

within the meaning of this definition.

Specifications.—1. Reading faces shall be permanently

fixed in position/
SPRING SCALES 99

2. All graduations shall be clear and distinct and equally

spaced and in no case shall their width be less than 0.008 inch.

S. The clear interval between the graduations shall not be

less than 0.04 inch.

4. The maximum value of the graduations on spring scales

used in the sale of foodstuffs at retail shall be 1 ounce: Provided, however, That this shall not apply to scales used exclusively in the sale of vegetables.

5. A spring scale shall have a definite and clear zero graduation and there shall be no stop to prevent the indicator from

going beyond the zero graduation. These conditions shall

be fulfilled whether the entire face is graduated or the graduations commence at a fixed load.

6. The indicator shall be firmly attached and reach to the

graduated divisions; or if the construction is such that the

indicator and reading face are in the same plane then there

shall not be a separation of the ends of the graduation lines

and the end of the indicator, of more than 0.04 inch, this

distance to be measured along the line of the graduations.

7. All indicators shall be so designed and constructed that

the indications are definite and may be read with precision.

8. The distance between the indicator and the reading

face shall not exceed 0.12 inch: Provided, however, That this

shall not be construed to prohibit the employment of an

additional indicator at a greater distance from the reading

face, designed and constructed so as to facilitate the correct

positioning of the eye of the observer properly to read the

indications of the scale and reduce parallax, when such additional indicator is clearly differentiated from the weight

indicator so that it will not be mistaken therefor.

9. All devices for adjusting the balance of a spring scale

shall be of such construction that they are operative or accessible only by the use of some tool or device which is outside
100 NATIONAL BUREAU OF STANDARDS

of and entirely separate from the movable mechanism of the

scale itself, such as a screw driver, wrench, etc., but not an

adjusting pin.

10. All devices for adjusting the level of a spring scale

shall be of such construction that they are operative or

accessible only by the use of some tool or device which is outside of and entirely separate from the leveling devices,

such as a screw driver, wrench, etc., but not an adjusting pin*

11. No device to alter the working or effective length of

the spring shall be placed on the outside of a spring scale.

12. Spring scales of the hanging type shall be freely sus- pended from the ring when in use.

13. If spring scales are provided with a hanging pan, this

shall be suspended from a ring and no hook will be allowed.

A hook may be used only on those scales for which no pan is provided.

14. Spring scales shall be so constructed that when a weight whose body has approximately equal diameter and

height and which represents one-half of the capacity of the

scale is shifted in any direction on the commodity plate,

pan, or scoop to a point one-half the distance between the

center and the edge of the plate, pan, or scoop, the additional

resulting error in the weight indication, due to this cause

alone, shall not exceed the tolerance allowed at the load in

question given in the tolerance table in the column headed

" Tolerance for shift test at half capacity ": Provided, however, That in this test the edge of the weight shall not be made

to project over the edge of the commodity plate, pan, or

scoop.

15. Spring scales whose weight indications are changed by

an amount greater than one-half the tolerance allowed, when

set in any position on a surface making an angle of 5 per

cent or approximately 3° with the horizontal shall be equipped
SPRING SCALES 101

with a device which will indicate when the scale is level. The

scale shall be rebalanced at zero each time its position is altered

during the test contemplated by this specification.

16. Spring scales of such construction that a weight or weights which are not visible can be added so as to affect the

indications oj the scale, shall be equipped vnth a device which

will clearly indicate on the customers1 side oj the scale when

the vieight or iveights have been added, and the value which it or they represent on the scale. 17. When tests are being made with both increasing and

decreasing loads on any spring scale, the indications on all increasing loads shall be within the usual tolerances provided,

and also at any stage of the test the range between corresponding observations for increasing and decreasing loads shall

not be greater than the sum of the tolerances in excess and in

deficiency for the load in question.

18. The specifications for each part of combination

spring and lever scales shall be the same as those for the

type of scale to which such part belongs.

19. All counter spring scales shall be maintained in level. 20. When not modified by the above, the specifications

given under the heading " Scales: General specifications"

shall apply to spring scales in so far as they are applicable.

Tolerances.—Except on the special tests described above? the tolerances to be allowed in excess or deficiency on all spring scales equipped with a device intended to compensate for changes in the elasticity of the springs due to temperature effects, shall be the values given in the appropriate

column in the tolerance table under the heading "Counter

scales." (See p. 97.)

Except on the special tests described above, the tolerances

to be allowed in excess or deficiency on all spring scales

not equipped with a device intended to compensate for
102 NATIONAL BUREAU OF STANDARDS

changes in the elasticity of the springs due to temperature

effects, shall be the values shown in the following table.

Provided, however, That the manufacturers' tolerances or the tolerances to be allowed on all new spring scales

described herein shall be one-half of the values given: And

provided further, That the tolerance shall in no case be less

than one-fourth of the minimum graduation on the reading face or dial, except that on new scales it shall in no case be less than one-eighth of such minimum graduation.

Load Tolerance for shift test at half capacity Pounds Ounces Ounce

1 1/8 1/16

2 1/4 1/16

3 1/4 1/16

4 1/2 1/8 5 1/2 1/8

6 1/2 1/8 7 1/2 1/4

8 3/4 1/4

10 3/4 1/4 12 1 1/4 15 1 5/16

20 5/16

24 m 3/8

25 m 3/8

Load Tolerance

Tolerance

for shift

test at half capacity Pounds Ounces Ounces 30 2 3/8

40 2 7/16

50 3 1/2

60 3 5/8

75 4 3/4

90 4 7/8

120 5 Hi

150 6 1%

200 8 2 300 12 3

Pounds 400 1 500

600 iy2 STRAIGKT-FACE SPRING SCALES

Definition.—A straight-face spring scale is a spring scale in

which an indicator is affixed to a spring without intervening

mechanism and registers the extension of the spring on a

straight graduated face.
STRAIGHT-FACE SPRING SCALES 103

Specifications.—1. The support for the spring shall be of

sufficient strength and rigidity to sustain the capacity load

of the scale without perceptible strain, and such support

shall be permanently affixed to the frame of the scale.

2. The graduated face shall be firmly riveted to the frame

at not less than three points.

3. The indicator shall be pointed in order to facilitate

accurate reading, and it shall not obscure the figures showing

the value of the graduations.

4. The value and spacing of the graduations shall satisfy

the requirements of the following table:

Capacity Maximum

value of

interval Minimum

distance between

graduations Pounds Pounds Inch 25 1/2 0. 03

50 1 . 03

100 1 . 03

200 2 . 03

800 5 ,04

400 5 .04

500 5 .04

5. When not modified by the above, the specifications

given under the headings " Scales: General specifications"

and " Spring scales" shall apply to straight-face spring scales

in so far as they are applicable.

Tolerances.—The tolerances to be allowed in excess or

deficiency on all straight-face spring scales shall be four

times the values given under the heading " Spring scales:

Tolerances."
104 NATIONAL BUREAU OF STANDARDS

COMPUTING SCALES

Definition.—A computing scale is a scale which, in addition

to indicating the weight, indicates the total price of the

amount of commodity weighed, for a series of unit prices.

Specifications.—1. Computing scales shall be correct in

both their weight and value indications.

2. Computing scale charts shall not repeat the same

values in any given column or row. This applies also to charts on which the value graduations are correctly placed,

but which, in addition, have a duplication of value figures

in any given column or row.

8. The value graduations on all computing charts shall

not exceed 1 cent on all prices per pound up to and including

SO cents. At any higher price per pound the value graduation shall not exceed 2 cents: Provided, however, That nothing

in the above shall be construed to prevent the placing oj a

special value graduation to represent each 5-cent interval.

These special graduations may take the form oj dots, staggered

graduations, or similarforms. They shall be so placed that their

meaning and value may be clearly understood, but they shall

not be placed in the space between the regular graduations.

4. All computing scales equipped with a drum-shaped

chart shall be so constructed that the opening on the dealers 9 side discloses at least two value graduations at the lowest price

per pound. These scales shall be so constructed that the opening on the customers' side discloses the smallest graduations

and a figure representing the proper number of main weight

units when any load is placed on the pan or platform.

5. All computing scales shall be equipped with weight

indicators on both the dealers7 and customers' sides, and

with a value indicator on the dealers' side, and the width

of such indicators shall not exceed 0.015 inch. The distance
COMPUTING SCALES 105

between the chart and the weight and the value indicators

shall in no case exceed 0.06 inch: Provident, however, That

this shall not be construed to prohibit the employment of an additional indicator at a greater distance from the chart,

designed and constructed so as to facilitate the correct

positioning of the eye of the observer properly to read the

indications of the scale and reduce parallax, when such

additional indicator is clearly differentiated from the weight

or the value indicator so that it will not be mistaken therefor.

6. Each indicator shall reach to each graduation of the

graduated scale in conjunction with which it is designed to be used; or if the construction is such that the indicator and

graduated scale are in the same plane then there shall not

be a separation of the ends of the graduations and the end of

the indicator of more than 0.04 inch, this distance to be

measured along the line of the graduations.

7. The weight graduations and the value graduations shall

be clear and distinct, but in no case shall their width be less than

0.008 inch.

8. The maximum value of the weight graduations on computing scales used in the sale of foodstuffs at retail

shall be 1 ounce: Provided, however, That this shall not

apply to scales used exclusively in the sale of vegetables.

9. The clear interval between the weight graduation marks

on all computing scales shall not be less than 0.04 inch. The

clear interval between the value graduation marks on all computing scales shall not be less than 0.02 inch: Provided, however, That the latter requirement shall not be construed to apply to the special value graduation denoting the 5-cent

interval, mentioned heretofore.

10. All devices for adjusting the balance of a computing

scale shall be of such construction that they are operative or

accessible only by the use of some tool or device which

1120r>4°-~29 8
106 NATIONAL BUREAU OF STANDARDS

is outside of and entirely separate from the movable mechanism of the scale itself, such as a screw driver, wrench, etc.,

but not an adjusting pin.

11. All devices for adjusting the level of a computing

scale shall be of such construction that they are operative

or accessible only by the use of some tool or device which

is outside of and entirely separate from the leveling devices,

such as a screw driver, wrench, etc., but not an adjusting

pin.

12. Computing scales whose weight indications are changed

by an amount greater than one-half the tolerance allowed,

when set in any position on a surface making an angle of

5 per cent or approximately 3° with the horizontal, shall be

equipped with a device which will indicate when the scale

is level, and in no case shall any pendulum operating the

scale be considered a leveling device. The scale shall be rebalanced at zero each time its position is altered during the test contemplated by this specification.

13. When tests are being made with both increasing and

decreasing loads on any computing scale, indications on

all increasing loads shall be within the usual tolerances

provided, and also at any stage of the test the range between

corresponding observations for increasing and decreasing

loads shall not be greater than the sum of the tolerances

in excess and in deficiency for the load in question. This

specification is to be construed as applying only to automatic-indicating scales.

11^. All devices intended to increase the capacity of computing scales by the addition of an added weight or weights

shall operate properly irrespective of the speed with which

they are manipulated.

15. All counter computing scales shall be maintained in

level.
COMPUTING SCALES 107

16. The specifications on a computing scale and on all parts of a computing scale, when not modified by the above,

shall be the same as those of the type to which the scale

under test belongs. Also, when not modified by the above,

the specifications given under the heading " Scales: General

specifications " shall apply to computing scales in so far as they are applicable.

Sensibility Reciprocal (SR).—When the scale is of such a type that the definition of SR is applicable, the maximum

allowable SR shall be the same value as is permitted for a noncomputing scale of the appropriate type.

Tolerances.—Except on the special tests described above,

the tolerances to be allowed in excess or deficiency on all spring computing scales equipped with a device intended to compensate for changes in the elasticity of the springs due

to temperature effects, and also all those not operated by

springs, shall be the values given in the appropriate column

in the tolerance table under the heading "Counter scales."

(See p. 97.)

Except on the special tests described above, the tolerances

to be allowed in excess or deficiency on all spring computing

scales not equipped with a device intended to compensate for

changes in the elasticity of the springs due to temperature

effects, shall be the values given in the appropriate column

in the tolerance table under the heading "Spring scales.'

-

(Seep. 102.)

Provided, however, That the manufacturers' tolerances or the tolerances to be allowed on all new computing scales

described herein shall be one-half of the values given: And

provided further, That the tolerance on all computing

scales equipped with a reading face or dial shall in no case be less than one-fourth of the minimum graduation on the

reading face or dial, except that on new computing scales
108 NATIONAL BUREAU OF STANDARDS

it shall in no case be less than one-eighth of such minimum

graduation.

CREAM-TEST AND BUTTERFAT-TEST SCALES

Definition.—A cream-test or butterfat-test scale is a

scale especially designed and adapted for determining the

fat content of cream or butter.

Specifications.1. All scales shall be provided with a

graduated scale or arc divided into at least 10 equal spaces,

over which the indicator shall play.

2. The clear interval between the graduations on the graduated scale or arc shall not be less than 0.04 inch.

3. The indicator shall be of such length as to reach to the

graduated divisions; or if the construction is such that the

indicator and graduated scale are in the same plane, then there

shall not be a separation of the ends of the graduations and

the end of the indicator of more than 0.04 inch, this distance

to be measured along the line of the graduations. The indicator shall terminate in a fine point to enable the readings to be made with precision.

4* All scales whose weight indications are changed by an

amount greater than one-half the tolerance allowed, when set in any position on a surjace making an angle oj 5 per cent

or approximately 3° with the horizontal, shall be equipped, with

leveling screvjs and with a device which will indicate when the

scale is level. The scale shall be rebalanced at zero each time

its position is altered during the test contemplated by this

specification.

5. All scales shall be so constructed and adjusted that when

the pans are released or disturbed the pointer will return to

its original position of equilibrium.

5a. All scales shall be so designed and constructed that

when an 18-gram weight is shifted to any position on the
CREAM-TEST SCALES 109

scale platform normally occupied by a cream-test bottle or

to any position on the scale platform in which the 18-gram

weight may reasonably be placed when samples are being

weighed, the additional resulting error in the weight indication, due to this cause alone, shall not exceed 1 grain.

6. When not modified by the above, the specifications

given under the heading " Scales: General specifications"

(except specification No. 2) shall apply to cream-test and

butterfat-test scales in so far as they are applicable.

Sensibility Reciprocal (SR).—The maximum SR allowable for these scales shall be 1 grain, or approximately

65 milligrams, when the scale is under maximum load:

Provided, however, That the manufacturers' maximum SR

or the maximum SR on all new scales shall be one-half of

of this value. (The maximum load is defined as the weight

of the sample used in each bottle multiplied by the number

of bottles for which the scale is designed, plus the total tare

of these bottles.)

(The term "sensibility reciprocal" or "SR" means the

weight required to move the position of equilibrium of the

beam, pan, pointer, or other indicating device of the scale a definite amount. In the case of scales provided with a

single indicator and a graduated scale or arc, one of which

oscillates with reference to the other to form a convenient

means for determining the position of equilibrium of the beam,

and which does not of itself directly indicate in terms of

weight, the SR is the weight required to cause a change in

the position of rest of the pointer equal to one division of

the graduated scale or arc. In the case of scales equipped with two indicators which

move in opposite directions and oscillate with reference to each other to form a convenient means for determining the

position of equilibrium of the beam, the SR is the weight re-
110 NATIONAL BUREAU OF STANDARDS

quired to cause a separation of the indicators of 0.04 inch,

measured in the direction of their movement.

Tolerances.—The tolerance to be allowed in excess or

deficiency on all cream-test and butterfat-test scales shall

be 1 grain or approximately 65 milligrams: Provided, however, That the manufacturers' tolerance or the tolerance to

be allowed on all new scales shall be one-half of this value.

This tolerance shall be applied to loads of 18 grams each, one of which shall be added when the scale is under approximately the maximum load as defined above.

PRESCRIPTION SCALES AND BALANCES

Definition.—Prescription scales and balances are scales

and balances designed for or adapted to weighing the ingredients of medicinal and other formulas prescribed by

physicians and others and entering into the ordinary trade

of pharmacists and chemists, and which are used or intended

to be used for such purpose.

These scales shall be of two classes, class A and class B.

A class A scale is one which meets all the requirements

given under the heading "Class A" below. Such a scale

may be used for all determinations of the character specified

above. A class B scale is one which is somewhat less sensitive and accurate than a class A scale but which complies

with all the requirements given under the heading "Class

B" below. Such a scale may be used only for the weighing

of loads of 10 grains or more.

CLASS A

Specifications.—1. All scales and balances shall be equipped

with a device which will accurately indicate the position of

equilibrium of the beam. If this device is provided with

only one indicating edge, line, or point, then it shall also be
PRESCRIPTION SCALES 111

provided with a graduated scale or arc. If this device consists of a scale or arc and a single indicating edge, line, or

point, or of two indicating edges, lines, or points, which

move in opposite directions, these shall be so designed and

constructed that when the beam vibrates one will oscillate

with reference to the other.

2. Any graduated scale or arc similar to that referred to in specification 1 shall be divided into equal spaces with at least 0.04 inch clear interval between the graduations.

3. If the indicating device referred to in specification 1 is provided with a single indicating edge, line, or point, this

shall reach to the graduated scale or arc; or if the construction is such that the indicator and graduated scale are in

the same plane, then there shall not be a separation of the

ends of the graduations and the end of the indicator of more

than 0.04 inch, this distance to be measured along the line

of the graduations. The indicator shall be so designed and

constructed as to enable the readings to be made with precision. If provided with two indicating edges, lines, or

points, these shall be sharply defined, and shall in no case be more than 0.04 inchfrom each other when the scale is in balance,

this space to be measured horizontally.

4. The distance between the graduated scale and the indicator

shall in no case exceed 0.04 inch: Provided, however, That this

shall not be construed to prohibit the employment of an

additional indicator at a greater distance from the graduated

scale, designed and constructed so as to facilitate the correct

positioning of the eye of the observer properly to read the

indications of the scale and reduce parallax, when such additional indicator is clearly differentiated from the regular

indicator so that it will not be mistaken therefor.

5. All knife-edges and bearings shall be made of hardened

and tempered steel, or of agate,
112 NATIONAL BUREAU OF STANDARDS

6. The graduations on all graduated beams shall be clear

and distinct, and in no case shall their width he less than 0.008

inch.

7. The clear space between graduations on all graduated

beams shall not be less than 0.04 inch.

8. All scales and balances shall be provided with a device jor

arresting the vibration of the beam.

9. All scales and balances shall be so constructed and

adjusted that when the beam is released or disturbed it will

return to its original position of equilibrium.

10. All scales and balances whose weight indications are changed by an amount greater than one-half the tolerance

allowed, when set in amy position on a surface making an angle

of 5 per cent or approximately 3° with the horizontal, shall be

equipped with a device which will indicate when the scale is

level, and in no case shall any pendulum operating the scale be

considered a leveling device. The scale shall be rebalanced at zero each time its position is altered during the test contemplated

by this specification.

11. For the purpose of applying the SR and tolerances

the capacity of all prescription scales and balances which are

in the State, either in use or in the stock of manufacturers

of or dealers in such apparatus, and which shall not have the

nominal or rated capacity marked upon them, shall be taken

to be 1 apothecaries' ounce (or 30 grams).

12. When not modified by the above, the specifications

given under the heading " Scales: General specifications

shall apply to prescription scales and balances in so far as they are applicable.

Sensibility Reciprocal (SR).—The maximum SR allowable for prescription scales and balances of a capacity of onehalf ounce (or 15 grams) or more shall be 0.2 grain (or 13 mg),

at the capacity or at any lesser load, with the exception that
PRESCRIPTION SCALES 113

when this value is larger than that represented by two of

the minimum graduations on any beam with which the scale

may be equipped, the latter value shall be applied and used

as the maximum SR, at the capacity or at any lesser load:

Provided, however, That the manufacturers7 SJl or the maximum SR on all new prescription scales and balances shall

be one-half of the value given unless this value is greater than

one of the minimum graduations on the beam, in which case

this latter value shall be applied and used as the maximum

SR.

Note.—If any prescription scale or balance has a smaller capacity

than one-half ounce (or 15 grams), the maximum SR to be allowed at the capacity or at any lesser load shall be the same proportionate part

of 0.2 grain (or 13 mg) that this capacity is of one-half ounce (or 15 grams)

.

(The term " sensibility reciprocal" or "SR" means the

weight required to move the position of equilibrium of the

beam, pan, pointer, or other indicating device of a scale or balance a definite amount. In the case of scales provided

with a single indicator and a graduated scale or arc, one of

which oscillates with reference to the other to form a con- venient means for determining the position of equilibrium of

the beam, and which does not of itself directly indicate in

terms of weight, the SR is the weight required to cause a change in the position of rest of the pointer equal to one

division of the graduated scale or arc. In the case of scales equipped with two indicators wilich

move in opposite directions and oscillate with reference to

each other to form a convenient means for determining the

position of equilibrium of the beam, the SR is the weight

required to cause a separation of the indicators of 0.04 inch,

measured in the direction of their movement,)
114 NATIONAL BUREAU OF STANDARDS

Tolerances.—The tolerances to be allowed in excess or

deficiency on the ratio of arms of prescription scales and

balances shall be the values shown in the following table:

Load Tolerance on ratio Ounces, ap. Grams Grains Milligrams

8 240 3. 2 208

4 120 1. 6 104

2 60 . 8 52

1 30 . 4 26

1/2 15 . 2 13 Note.—If any prescription scale or balance has a smaller capacity

than one-half ounce (or 15 grams), the tolerance to be allowed shall be the same proportionate part of 0.2 grain (or 13 mg) that this capacity is of one-half ounce (or 15 grams).

If the scale is equipped with a graduated beam, the toler- ance at any graduation on the beam shall be equal to the

actual SR of the scale at the load in question.

CLASS B NOTE.—In the case of a drug store doing prescription work, which

is provided with a class A prescription scale or balance, then and in that case only an additional prescription scale or balance of class B

may also be sealed, but only for the weighing of loads of 10 grains or more, and such scale shall not be used for weighing any load of less than 10 grains.

Specifications.—All class B scales and balances shall be

conspicuously and clearly marked with the words " Class B.

Not to be used in weighing loads of less than 10 grains,"
PRESCRIPTION SCALES 115

or with a similar and suitable wording conveying the same

information. 10 All class B scales and balances shall conform to all the

specifications for class A scales and balances, but will be

allowed the following sensibility reciprocals and tolerances:

Sensibility Reciprocal (SR).—The maximum SR allowable

for class B prescription scales and balances shall be 0.5 grain, at the capacity or at any lesser load: Provided, however,

That the manufacturers' maximum SR or the maximum SR

on all new class B prescription scales and balances shall be

one-half of the value given.

Tolerances.—The tolerances to be allowed in excess or

deficiency on the ratio of arms of all class B prescription

scales and balances shall be the values shown in the following

table

:

Load Tolerance on ratio Ounces, ap. Grams Grains Milligrams

8 240 8. 0 520

4 120 4. 0 260

2 60 2. 0 130

1 30 1. 0 65

1/2 15 . 5 30

Note.—If any class B prescription scale or balance has a smaller

capacity than one-half ounce (or 15 grams), the tolerance to be allowed

shall be the same proportionate part of 0.5 grain (or 30 mg) that this capacity is of one-half ounce (or 15 grams).

i° In the case of class B prescription scales and balances, which are hereafter manufactured

in the State or brought into the State, this requirement shall be fulfilled by the manufacturer.

In all other cases the inscription shall be placed upon such scales and balances by the weights and measures official.
116 NATIONAL BUREAU OF STANDARDS

If a class B prescription scale or balance is equipped with

a graduated beam, the tolerance to be allowed at any graduation on the beam shall be 0.3 grain (or 20 mg), unless this

value is less than the actual SR of the scale at the load in

question, in which case this actual SR shall be used as the

tolerance at any graduation on the beam.

WEIGHTS

Specifications.—1. Weights shall be made of steel, iron,

brass, or any other metal or alloy of metals not softer than

brass: Provided, however, That weights below one-fourth ounce shall not be made of iron or steel, but may be made

of aluminum.

2. Weights shall have smooth surfaces, and no weight of

more than 1 gram, 1 pennyweight, or 1 scruple shall have

sharp points or corners.

3. Weights shall not be covered with a soft or thick coat

of paint or varnish.

4. All holes in which foreign material is to be placed

for adjusting purposes shall be of such form that the material will be permanently and securely held in place. In no case shall this adjusting material project beyond the

surface of the weight.

5. Rings on weights shall not be split or removable.

6. All weights shall be clearly marked with their nominal value, and in addition weights intended for use on multiplying-lever scales shall be clearly marked with the value they

represent when used upon the scale jor which they are intended:

Provided, however, That the values of weights of less than 1 gram, 1 pennyweight, or 1 scruple may be designated by dots,

lines, figures, distinctive shape, or other appropriate means.

Tolerances.—The tolerances to be allowed in excess or

deficiency on commercial weights shall be the values shown

in the following table: Provided, however, That the manufac-
WEIGHTS 117

hirers' tolerances or the tolerances to be allowed on new

commercial weights shall be one-half of the values given

:

Avoirdupois System

1Weight

a oieraiicc, weights for equal-arm

scales, ratio

1:1

Tolerance, counterpoise weights for multiplying-lever scales

Ratio less than 100:1 Ratio 100:1 and less than 1,000:1 Ratio 1,000:1 and over

Pounds Grains Grains Grains 50 100. 0 60. 0 40. 0 20. 0

25 _ 60. 0 36. 0 24. 0 12. 0 20 60. 0 36. 0 24. 0 12. 0

15 40. 0 24. 0 16. 0 8. 0

10 _ _ 40. 0 24. 0 16. 0 8. 0

8 30. 0 18. 0 12. 0 6. 0

5__ 30. 0 18. 0 12. 0 6. 0 4 20. 0 12. 0 8. 0 4. 0

3 20. 0 12. 0 8. 0 4. 0

2_ 15. 0 9. 0 6. 0 3. 0

1_ 10. 0 6. 0 4. 0 2. 0

Ounces 10_ 10. 0 6. 0 4. 0 2. 0

8 5. 0 3. 0 2. 0 1. 0

5 5. 0 3. 0 2. 0 1. 0 4 5. 0 3. 0 2. 0 1. 0

2 3. 0 1. 8 1. 2 . 6

1 2. 0 1. 2 . 8 . 4

1/2 2. 0 1. 2 . 8 . 4

1/4 1. 0 . 6 . 4 . 2

1/8 . 5 . 3 . 2 . 1 1/16 . 5 . 3 . 2 . 1 1/32 . 5 . 3 . 2 . 1 1/64 . 2 . 12 . 08 . 04
118 NATIONAL BUREAU OF STANDARDS

The tolerances to be allowed in excess or deficiency on

apothecaries' prescription weights shall be the values shown

in the following table : Provided, however, That the manufacturers' tolerances or the tolerances to be allowed on new

apothecaries' prescription weights shall be one-half of the

values given:

Apothecaries' System

Weight Tolerance Weight Tolerance

Ounces, ap. 12

Grains

4. 0

4. 0

3. 0

3. 0

2. 0

2. 0

2. 0

1. 0

1. 0

1. 0

. 7

. 6

. 5

. 3

. 2

Scruples 3Grains

0. 3

. 25

. 15

. 15

. 12

. 08

. 04

. 03

. 02

. 015

. 01

10 2 8 1 5 Grains 20

4 10

3 5

2 2

1Drams 1 8 .5

6 .2___ . 4 . 1 32

1.5
WEIGHTS 119

Metric System

Weight Tolerance Weight Tolerance Grams 500

Milligrams

350

200

150

100

50

40

25

15

10

Milligrams

500

Milligrams 74

3

2

1

1

200 200

100_ 100___ _ 50 50

20 20

10 10

5

2

1 The tolerances to be allowed in excess or deficiency on

weights to be used in connection with cream-test and butterfat-test scales and moisture-test scales shall be 20 milligrams on the 18-gram weight and 10 milligrams on the 9-gram and

10-gram weights: Provided, however, That the manufacturers' tolerances or the tolerances to be allowed on new

weights shall be one-half the values given.
Part III.—CITATION TO CERTAIN CODES OF SPECIFICATIONS AND TOLERANCES FOR COMMERCIAL

WEIGHING AND MEASURING DEVICES, OTHER

THAN THOSE ADOPTED BY THE NATIONAL CONFERENCE ON WEIGHTS AND MEASURES

INTRODUCTION

Below are given references to and brief descriptions of

certain codes of specifications and tolerances affecting a

variety of groups of commercial weighing and measuring

devices. With a few exceptions these codes relate to devices

which are not covered by the codes adopted by the National

Conference on Weights and Measures; the exceptions mentioned are cases in which there is a well-recognized code

adopted or indorsed by some other organization, covering

similar ground to that covered by a conference code. In

the case of the codes for clinical thermometers and moisturetest scales the devices in question are noncommercial.

A short description is given in the case of each code cited, so that the general scope of these codes may be made clear.

The source from which copies of each code may be secured is also stated. In some instances the group responsible for

the development of a code is also described.

The list which is here given does not purport to represent

every code which might be cited. Particularly in the specifications and tolerances of the several States there are nu- merous instances in which mention is made of items which

might be considered to fall within the scope of this list but

upon which no comment is made herein; moreover, no mention is made below of State codes based upon codes adopted by

the National Conference on Weights and Measures, but

differing in some respects therefrom.

120
CITATION TO CODES 121

It may also be mentioned that the several departments of

the Federal Government have issued from time to time purchase specifications governing their purchases of weighing

and measuring equipment, and that no mention of these is made below.

GENERAL SPECIFICATION FOR SCALES

Federal Specifications Board Specification No. 473

This specification was officially promulgated on March 5,

1927, for the use of the departments and independent establishments of the Government in the purchase of weighing

scales.

This code is based upon and very closely follows the general specifications for scales as adopted by the National Conference on Weights and Measures. Some additional material has been included along the lines of design requirements,

particularly some of the provisions of the " Specifications for

the manufacture and installation of motor-truck, built-in,

self-contained, and portable scales for railroad service " of

the Americal Railway Engineering Association.

Copies of this specification may be secured upon application to the Federal Specifications Board, care of the Bureau

of Standards, Washington, D. C. 1 RAILROAD TRACK SCALES

Specifications for the Manufacture and Installation of Railroad Track

Scales—Circular of the Bureau of Standards No. 83? January, 1920—

Publication of the American Railway Association Under the Foregoing Title This code was prepared by a joint committee of the American Railway Association, the American Railway Engineering

Association, the Railroad and Warehouse Commission of the

State of Minnesota, the National Scale Men's Association,

112054°—29 9
122 NATIONAL BUREAU OF STANDARDS

the Scale and Balance Manufacturers' Association, and the

National Bureau of Standards. It was approved by the

American Kailway Association November 19, 1919.

This code is intended to apply to knife-edge scales of the

straight and torsion lever types for weighing scales in railroad

service. It is a detailed code containing engineering and

design requirements and also specifications as to foundations,

scale-beam house, approach rails, dead rails, protection from

weather effects, lighting, drainage, ventilation, etc., and general installation requirements.

Copies of Circular of the Bureau of Standards No. 83 may

be secured through purchase from the Superintendent of

Documents, Government Printing Office, Washington, D. C,

at 5 cents per copy.

Copies of " Specifications for the Manufacture and Installation of Railroad Track Scales/' as published by the American

Railway Association, may be secured through application to

the secretary of that association, 75 Church Street, New

York, N. Y.

Federal Specifications Board Specification No. 314

This specification was officially promulgated on August 8,

1925, for the use of the departments and independent establishments of the Government in the purchase of railroad

track scales.

The " detail requirements" of this code are the same as those embraced in Circular of the Bureau of Standards No.

83 referred to above.

Copies of this specification may be secured upon application to the Federal Specifications Board, care of the Bureau

of Standards, Washington, D. C.
CITATION TO CODES 123

Specifications and Tolerances for Railroad Track Scales—State of Minnesota

These requirements are similar to the code published in

Circular of the Bureau of Standards No. 83.

Copies of the Minnesota specifications and tolerances may

be secured through application to the State Department of

Scales, Weights, and Measures, Corn Exchange Building,

Minneapolis, Minn.

TWO-SECTION, KNIFE-EDGE RAILROAD TRACK

SCALES

Circular of the Bureau of Standards No. 333, July, 1927

The detailed work of preparing this code was done by the

yards and terminals committee of the American Railway

Engineering Association, on which the transportation and

manufacturing interests and the National Bureau of Standards were represented. The code bears the approval of the

National Scale Men's Association and the Scale a^d Balance

Manufacturers' Association.

This code is similar in its scope to the code given in Circular

of the Bureau of Standards No. 83, but relates, of course,

to two-section scales whereas the earlier code related to

scales of four sections or more. Copies of Circular of the Bureau of Standards No. 333 may

be secured through purchase from the Superintendent of

Documents, Government Printing Office, Washington, D. C,

at 10 cents per copy.

The code is also published in American Railway Engineering Bulletin No. 294, volume 28, pages 557 to 611, February,

1927.
124 NATIONAL BUREAU OF STANDARDS

HAND-OPERATED GRAIN-HOPPER SCALES

Circular of the Bureau of Standards No. 199, March, 1925

This code was developed by a conference participated in

by the Weighmasters'-Seale Men's Conference, Minnesota

Track and Hopper Scale Department, National Scale Men's

Association, Grain Dealers' Grain Conference Committee,

Elevator Builders and Designers, Scale and Balance Manufacturers' Association, and the National Bureau of Standards,

the last mentioned acting in an advisory capacity.

The code contains engineering and design requirements and

requirements for installation, attachments, accessories, etc. Copies of Circular of the Bureau of Standards No. 199

may be secured through purchase from the Superintendent

of Documents, Government Printing Office, Washington,

D. C, at 10 cents per copy.

AUTOMATIC HOPPER, HAND-OPERATED HOPPER,

AND RAILROAD TRACK SCALES USED FOR WEIGHING BULK GRAIN

American Railway Association, Grain Circular No. 1, January, 1922

This code contains requirements as to scale design, installation, operation, performance, and testing, for equipment of

the character indicated. It was issued pursuant to the rec- ommendation of the Interstate Commerce Commission, supplementary report, claims for loss and damage of grain,

decided December 13, 1920, Docket 9009 (56 I. C. C. 347),

and was published by the American Railway Association as

effective January 1, 1922.

The character of the requirements of this code follow the

lines of similar codes for scales in ordinary service with the

exception that the requirements for grain-weighing service

are, in general, more rigid.
CITATION TO CODES 125

Copies of the American Railway Association Grain Circular No. 1 may be secured through application to the secre- tary of that association, 75 Church Street, New York, N. Y.

Specifications and Tolerances for Hopper and Track Scales for the

Handling of Bulk Grain—State of Minnesota

These requirements are similar to those of the American

Railway Association cited above.

Copies of the Minnesota requirements maj^ be secured upon

application to the State Department of Scales, Weights, and

Measures, Corn Exchange Building, Minneapolis, Minn.

MOTOR-TRUCK, BUILT-IN, SELF-CONTAINED, AND

PORTABLE SCALES FOR RAILROAD SERVICE

Letter Circular of the Bureau of Standards No. 152, January, 1925

Circular of the American Railway Association IV-39

This code is intended for knife-edge scales of the straight

and torsion lever types equipped with beams for weighing

less-than-carload freight. The code contains detailed engineering and design requirements and also requirements for

foundation, pit, beam house, lighting, drainage, ventilation,

installation, etc. Copies of Letter Circular of the Bureau of Standards No.

152 may be secured upon application to the Bureau of Standards. Copies of Circular of the American Railway Association IV-39 may be secured through application to the sec- retary of that association, 75 Church Street, New York, N. Y.

This code was also published in the July 23 number of the

American Railway Engineering Association Bulletin, No. 257,

volume 25.
126 NATIONAL BUREAU OF STANDARDS

WAGON AND MOTOR-TRUCK SCALES

General Requirements for the Construction and Installation of Wagon

and Motor-Truck Scales—State of Minnesota

This code of specifications and tolerances is under consideration by the Department of Scales, Weights, and Measures

of the State of Minnesota. Copies of this code, if and when

adopted and issued, may be secured through application to

the State Department of Scales, Weights, and Measures, Corn

Exchange Building, Minneapolis, Minn.

MOISTURE-TEST SCALES

Specifications and Tolerances for Weighing and Measuring Devices

State of Wisconsin

These specifications relate to small scales used in determining the moisture content of cheese and butter, and have

been in effect in Wisconsin for a number of years. While

these scales are noncommercial, the Wisconsin specifications state that when tested they will be sealed only

when they comply with the specifications and tolerances

established.

Copies of these specifications may be secured upon re- quest, from the State Division of Weights and Measures,

Dairy and Food Department, Madison, Wis.

LIQUID-MEASURING DEVICES

Federal Specifications Board Specification No. 362

This specification was officially promulgated on December 24, 1925, for the use of departments and independent

establishments of the Government in the purchase of liquidmeasuring devices, retail type.

The " detail requirements" of this code are substantially

the same as those embraced in the conference code for

liquid-measuring devices.
CITATION TO CODES 127

Copies of this specification may be secured upon application to the Federal Specifications Board, care of the Bureau

of Standards, Washington, D. C.

ELECTRICITY METERS

Circular of the Bureau of Standards No. 56, September, 1923

In Circular of the Bureau of Standards No. 56, second

edition, issued September, 1923, electric light and power

station operation, distribution, metering, utilization, and

safety provisions are discussed, and a complete set of rules

suitable for adoption by State public utilities commissions

is presented. Existing regulations of the States are summarized.

Copies of Circular of the Bureau of Standards No. 56 may

be secured through purchase from the Superintendent of

Documents, Government Printing Office, Washington, D. C,

at 60 cents per copy.

Code for Electricity Meters, Third Edition, National Electric Light

Association, Publication No. 267-70

The present revision of this code has been made under the

joint sponsorship of the Association of Edison Illuminating

Companies, the National Electric Light Association, and the

National Bureau of Standards by a sectional committee representing all interested organizations, in accordance with the

procedure established by the American Engineering Standards Committee for the revision of American standards.

This code is approved as American standard by the American

Engineering Standards Committee as of February 20, 1928,

designated as A. E. S. C. standard No. C12—1928.

The code contains sections on definitions, standards, metering, acceptance specifications, installation methods, test methods, laboratory and service tests, and demand meters.
128 NATIONAL BUREAU OF STANDARDS

Copies of this code may be secured through purchase from

the National Electric Light Association, 420 Lexington

Avenue, New York, N. Y., at $2 per copy.

GAS METERS

Circular of the Bureau of Standards No. 32, December, 1920—Circular

of the Bureau of Standards No. 309, December, 1926

In Circular of the Bureau of Standards No. 32 a form is proposed for a model city gas ordinance, and rules are suggested for adoption of State public-service commissions.

The technical matters involved are fully discussed and a summary is given of regulations in effect in numerous large

cities. Circular of the Bureau of Standards No. 309 contains a

description of the construction and operation of a variety

of gas-measuring instruments and methods of testing and

adjusting such instruments.

Copies of these circulars of the Bureau of Standards may

be secured through purchase from the Superintendent of

Documents, Government Printing Office, Washington, D. C,

No. 32 at 20 cents per copy, and No. 309 at 40 cents per

copy.

WATER METERS

Standard Specifications for Cold-Water Meters, Disk Type

This code was developed by a group comprising the joint

committee of the American Water Works Association and

the New England Water Works Association, and the Committee of Water Meter Manufacturers. The code was adopted

by the American Water Works Association June 9, 1921,

and by the New England Water Works Association September 14, 1921.
CITATION TO CODES 129

The code contains manufacturing and performance requirements and, as published, includes an outline of the equipment

necessary for conducting tests and an outline of test methods.

Copies of this specification may be secured upon application to the secretary, American Water Works Association,

170 Broadway, New York, N. Y., or to the secretary, New

England Water Works Association, 715 Tremont Temple,

Boston, Mass.

LEATHER-MEASURING DEVICES

Specifications and Tolerances for Weighing and Measuring Devices

State of Massachusetts; Specifications and Tolerances for Weighing

and Measuring Devices—State of Ohio

Requirements for leather-measuring machines have been

in effect in Massachusetts for a number of years. A short

code based upon the Massachusetts requirements has recently

been promulgated in Ohio.

Copies of the Massachusetts requirements may be secured

by addressing the State Division of Standards, Department

of Labor and Industries, Boston, Mass. Copies of the Ohio

requirements may be secured by addressing the State

Division of Foods and Dairies, Department of Agriculture,

Columbus, Ohio.

CLINICAL THERMOMETERS

Clinical Thermometers, Commercial Standard CS1-28

This specification was formulated by the producers in co- operation with the National Bureau of Standards and later

approved by representative conference of manufacturers, distributors, and users of clinical thermometers, final action being

taken by this group on March 30, 1928. The plan followed

in the development of this specification was the regular procedure set up by the Bureau of Standards for the establish-
130 NATIONAL BUREAU OF STANDARDS

ment of " Commercial Standards/9 the Bureau of Standards

acting in an advisory and coordinating capacity only. The

requirements of this code will be made the basis for the

testing of clinical thermometers by the Bureau of Standards.

Although clinical thermometers are not commercial measuring devices, reference to this code is included here because

of the interest of weights and measures departments in such

regulations.

This code contains requirements of the following character:

Preliminary inspection, character of pigment, test for en- trapped gas, hard shaker test, retreat test, accuracy, adjusting, and certificate.

Copies of Clinical Thermometers, Commercial Standard

CSl-28, may be secured through purchase from the Superintendent of Documents, Government Printing Office, Washington, D. C, at 5 cents per copy.

State and City Specifications and Tolerances

Specifications and tolerances for clinical thermometers are in effect in Massachusetts, Connecticut, Michigan, and New

York City. Copies of these requirements may be secured,

respectively, from the following : State Division of Standards,

Department of Labor and Industries, Boston, Mass.; State

Department of Health, Hartford, Conn.; State Board of

Pharmacy, Lansing, Mich.; and the Department of Health,

505 Pearl Street, New York, N. Y.