Inside this Issue

NCWM Affirms Method of Sale for

“Products Sold in Pressurized Con‐

tainers Using Bag on Value Technol‐

ogy” 1

Testing Compressed Natural Gas 

Retail Motor‐Fuel Dispensers, 

Arriving Prepared to Test 3

Training and Events Calendar 2

U.S. National Working Group on 

Alternative Test Methods, Field 

Task Group Activities 9

1

Volume 5 Issue 7

December 10, 2014

OFFICE OF WEIGHTS AND

MEASURES

General Inquries: (301) 975‐4004; e‐mail:

owm@nist.gov

Office Chief, Carol Hockert: e‐mail:

carol.hockert@nist.gov

Newsletter Editor: Linda Crown; (301) 975‐

3998; e‐mail: linda.crown@nist.gov

NCWM Affirms Method of

Sale for

“Products Sold in Pressur‐

ized Containers Using Bag

on Valve Technology ”

Byline: David Sefcik

Since January of 2011, the National Conference on Weights and Measures

(NCWM), along with industry representatives, trade associations, and other

stakeholders have been trying to reach a consensus on the method of sale

for pressurized containers utilizing “bag on valve (BOV)” technology. Unlike

In the Field

Is there a W&M topic that you would like to

have appear in the Weights and Measures

Connection?

How can we better serve our W&M commu‐

nity?

Do you have a safety tidbit to share?

Do you have a W&M event that you wish to

post in the Connection’s calendar?

Submissions can be sent to the Editor, Linda

Crown at Linda.Crown@nist.gov

The Office of Weights

and Measures

wishes you a

safe and happy 

holiday season!
W&M Connection 2 Volume 5 Issue 7

Training and Events

Calendar 

2015

Registration for training in the NIST Office of

Weights and Measures is handled by Yvonne

Branden at yvonne.branden@nist.gov.

Course descriptions can be viewed on the Of‐

fice of Weights and Measures website at

http://www.nist.gov/pml/wmd/calendar.cfm

and clicking on the name of the course. 

January 18 ‐ 21 (4 days)

National Conference on Weights and Meas‐

ures Interim Meeting

Daytona Beach, FL

Contact: info@ncwm.net

January 26 ‐ 30 (5 days)

Fundamentals of Metrology

Class No. 5329

NIST/Gaithersburg, MD

February 9 ‐ 13 (5 days)

Fundamentls of Metrology

Class No. 5347

NIST/Gaithersburg, MD

February 12 (2 hr)

Webinar ‐ Conducting an Effective Manage‐

ment Review

2:00 p.m. to 4:00 p.m.

Class No. 5295

February 18 ‐ 19 (2 days)

Handbook 130, Price Verification

Class No. 5350

Salt Lake City, UT

February 24 ‐ 26 (3 days)

Train the Trainer

Class No. 5352

NIST/Gaithersburg, MD

February 26

NTEP Belt‐Conveyor Sector Meeting

St. Louis, MO

Contact: info@ncwm.net

February 26 (2 hr)

Webinar ‐ Internal Auditing Best Practices

2:00 p.m. to 4:00 p.m.

Class No. 5296

March 2 ‐ 6 (5 days)

Fundamentos de Metrología

Class No. 5348

NIST/Gaithersburg, MD

(continued pg. 3)

traditional aerosols in which the product (pay‐load) is mixed with gas in the

container and expelled simultaneously when dispensed, BOV is designed to

separate the product from the gas inside the container so that when the prod‐

uct is dispensed from a barrier package only the product is expelled, while

the gas remains in the package and is never mixed with the product. 

Aerosols and similar pressurized containers are required to be sold by net

weight in accordance with Section 10.3. Aerosols and Similar Pressurized Con‐

tainers of the Uniform Packaging and Labeling Regulation in NIST Handbook

130, “Uniform Laws and Regulations in the Areas of Legal Metrology and En‐

gine Fuel Quality.” This has been the traditional method of sale and firmly

established general consumer usage and trade custom with respect to the

terms used in expressing a declaration of quantity for over 45 years. 

The issue is some pressurized containers using

BOV technology are being labeled and sold with

quantity statements in terms of volume (fluid

ounces). Products using BOV technology versus

traditional aerosol products cannot be easily dis‐

tinguished when placed side by side, creating a

challenge when consumers attempt to make

value comparisons when the two different meth‐

ods of sale (i.e., weight and volume) are used. 

On January 9, 2014, a meeting was held at the National Institute of Standards and

Technology (NIST), in Gaithersburg, Maryland, www.nist.gov/pml/wmd/bov‐wrk‐

grp.cfm to discuss the appropriate method of sale for products sold in pressurized

containers using bag on valve (BOV) technology. This was done at the recom‐

mendation of the NCWM Laws and Regulations Committee. The meeting was

attended by 34 participants including representatives from the Food and Drug

Administration (FDA), Federal Trade Commission (FTC), Environmental Pro‐

tection Agency (EPA), Consumer Product Safety Commission (CPSC), state and

county regulatory officials, industry trade associations, and individual com‐

panies representing both manufacturers and retailers. The purpose of the

meeting was to clearly define the problem, understand current federal and

state laws and regulations, and determine if net weight was the appropriate

method of sale for BOV containers. At the conclusion of the meeting, there

was unanimous agreement that weight should be required as the method of

sale for all pressurized containers, regardless of technology. The current re‐

quirement (weight as the method of sale) in the NIST Handbook 130 is not

intended to take into consideration the various technologies use to fill and

dispense pressurized containers. 

At the 99th NCWM Annual Conference held in Detroit, Michigan, July 13 ‐ 17,

2014, the NCWM adopted the amended language below to clarify Section

10.3., making it clear that the method of sale applies to aerosols and other

self‐pressurized containers (including those utilizing BOV technology).

This amended language is effective January 2015, and includes a provision

allowing BOV manufacturers who are labeling their BOV containers by volume

three years to bring their packaging and labeling into compliance. This will

allow manufacturers and retailers to sell existing inventories through 2017. 
W&M Connection 3 Volume 5 Issue 7

10.3. Aerosols and Other Pre‐Pressurized Containers Dispensing

Product Under Pressure. – The declaration of quantity on an aerosol

and on other pre‐pressurized containers dispensing products under

pressure shall disclose the net quantity of the commodity (including

propellant, where applicable) in terms of weight that will be expelled

when the instructions for use as shown on the container are fol‐

lowed. 

Note: Enforceable on packages using bag‐on‐valve (BOV) technology

after January 1, 2018. 

(Amended 2014)

This amendment supports and further strengthens the requirement that the

traditional method of sale for aerosols and other pre‐pressurized containers

dispensing product under pressure (including those using BOV technology)

must be sold by weight.

For more information, contact David Sefcik at david.sefcik@nist.gov, (301)

975‐4868. You may also contact Lisa Warfield at lisa.warfield@nist.gov,

(301) 975‐3308.

The NIST Office of Weights and Measures

homepage: http://www.nist.gov/pml/wmd/index.cfm

March 9 ‐ 12 (4 days)

Handbook 133, “Checking the Net Contents

of Packaged Goods,” Basic

Class No. 5363

Southgate, CA

March 16 ‐ 27 (2 weeks)

Mass Metrology Seminar

Class No. 5333

NIST/Gaithersburg, MD

March 17 ‐ 19 (3 days)

New Administrator Workshop

Class No. 5368

NIST/Gaithersburg

March 19 (2 hr)

Webinar ‐ Contract Review

2:00 p.m. ‐ 4:00 p.m.

Class No. 5343

March 26 (2 hr)

Webinar ‐ Document Control and Record

Keeping

2:00 p.m. ‐ 4:00 p.m.

Class No. 5344

April 1 (2 hr)

Webinar ‐ NISTIR 6969, SOP 8, Part 1

2:00 p.m. ‐ 4:00 p.m.

Class No. 5364

April 2 (2 hr)

Webinar ‐ NISTIR 6969, SOP 8, Part 2

2:00 p.m. ‐ 4:00 p.m.

Class No. 5365

April 13 ‐ 17 (5 days)

Handbook 133, “Checking the Net Contents

of Packaged Goods,” Basic

Class No. 5362

Indianapolis, IN

April 13 ‐ 16 (4 days)

SEMAP**

Class No. 5357

Florida

April 14 ‐ 16 (3 days)

Train the Trainer

Class No. 5353

NIST/Gaithersburg, MD

May 4 ‐ 7 (4 days)

WRAP**

Class No. 5358

Olympia, WA

May 4 ‐ 8 (5 days)

Northeast Weights and Measures Associa‐

tion (NEWMA) Annual Meeting

Saratoga Springs, NY

Contact: James Cassidy, 

jcassidy@cambridgema.gov

(continued pg 4)

Testing Compressed 

Natural Gas Retail Motor‐

Fuel Dispensers

ARRIVING PREPARED TO TEST

Byline: Rick Harshman

As the developing infrastructure for fueling vehicles that use compressed nat‐

ural gas (CNG) as an engine fuel continues to unfold, some weights and meas‐

ures jurisdictions are raising questions about the equipment needed to test

the retail motor‐fuel dispensers (RMFDs) that dispense CNG. The testing of

CNG RMFDs necessitates some advance planning to ensure that all of the

proper test equipment is available on the day that testing is to take place.

There is information that officials can gather beforehand that will allow them

to make a preliminary determination of whether or not the equipment made

available to them for testing will be adequate and improve the likelihood that

a complete test, as outlined in NIST EPO No. 28 Examination Procedure Out‐

line for Compressed Natural Gas (CNG) Retail Motor Fuel Dispensers, can be

performed on the date that testing is scheduled. This article identifies the

information that needs to be known about the test equipment as well as the

RMFD to be tested and explains how this information is used to make this

determination. 
W&M Connection 4 Volume 5 Issue 7

Note: The word “preliminary” prefaces the word “determination” in the

above paragraph for good reason. CNG RMFDs are tested gravimetrically,

which requires the use of a suitable reference scale that has been proven to

be sufficiently accurate and capable of repeating its indications. The refer‐

ence scale is tested onsite, immediately prior to being used as a transfer stan‐

dard in testing the CNG RMFDs. Testing of the reference scale typically takes

place outdoors, under existing weather conditions, and in close proximity to

where the scale will be used to weigh test drafts of CNG. The results from

such onsite testing determine whether or not the scale performs well enough

to be used as a standard in testing another device; in this case, a CNG RMFD.

For this reason, even when a preliminary determination has been made that

the reference scale being made available for testing is adequate (i.e., based

on elements of its design), it isn’t until the results of testing the reference

scale onsite are known that a final determination can be made relative to its

adequacy. 

Dispenser Information

There are two things that officials need to find out about a CNG RMFD that

they are planning to test. The first is the minimum measured quantity (MMQ)

marked on the device. The second is how mass units are accessed.

MMQ. NIST Handbook 44, Specifications, Tolerances, and Other Technical

Requirements for Weighing and Measuring Devices, Section 3.37. Mass Flow

Meters Code paragraphs S.5. Markings and N.1. Minimum Measured Quantity

requires that the MMQ be specified and marked on the device by the manu‐

facturer. 

S.5. Markings. – A measuring system shall be legibly and in‐

delibly marked with the following information:

(a) ...

minimum measured quantity; and

(b) ...

N.1. Minimum Measured Quantity. – The minimum measured

quantity shall be specified by the manufacturer.

NIST HANDBOOK 44, SECTION 3.37. MASS FLOW METERS CODE PARAGRAPHS S.5. MARKINGS AND

N.1. MINIMUM MEASURED QUANTITY

The MMQ provides the critical piece of information needed to determine whether or not the value of the scale division (d)

of the reference scale will be small enough for the scale to be used as a standard in testing the RMFD. To be small enough,

the value of “d” must be less than or equal to one‐tenth the smallest tolerance to be applied to the RMFD under test. The

smallest applied tolerance on a CNG RMFD is the tolerance that gets applied to the smallest test draft; which in this case,

is a test draft equal to the MMQ. The variables used to determine the maximum allowable division size for the reference

scale are expressed in formula (1). 

Reference scale division (d) ≤ smallest test load x tolerance ÷ 10 (1)

Rearranging some of the variables in this equation also makes possible a determination of the smallest test load of CNG to be

delivered into the test cylinder during testing. Formula (2) establishes the smallest permissible test load or test draft size.

May 18 ‐ 22 (5 days)

Central Weights and Measures Association

(CWMA) Annual Meeting

Columbus, OH

Contact: Sherry Turvey, 

sherry.turvey@kda.ks.gov

June 1 ‐ 5 (5 days)

HB 133, “Checking the Net Contents of Pack‐

aged Goods,” Basic

Class No. 5345

Indianapolis, IN

June 1 ‐ 11 (2 weeks)

Advanced Mass Seminar (Rev 2015)

Class No. 5349

NIST/Gaithersburg, MD

July 18 ‐ 21 (4 days)

National Conference on Weights and Meas‐

ures (NCWM) Annual Meeting

Philadelpha, PA

Contact: info@ncwm.net

July 19 ‐ 23 (5 days)

NCSL International Conference 2015

Metrology and the Quality of Life

Orlando, FL

Information: www.ncsli.org

August 13 (2 hr)

Webinar ‐ Contract Review

2:00 p.m. ‐ 4:00 p.m.

Class No. 5334

August 17 ‐21 (5 days)

Volume Metrology Seminar

Class No. 5356

NIST/Gaithersburg, MD

August 19 ‐ 20 (2 days)

NTEP Grain Analyzer Sector Meeting

Live Web Meeting

Details unavailable at this time.

(continued pg 5)
W&M Connection 5 Volume 5 Issue 7

Information to be posted at:

https://www.ncwm.net/ntep/sectors/grain‐

analyzer/registration

August 25 ‐ 26 (2 days)

Weighing Sector Meeting

Denver, CO

Information at: 

www.ncwm.net/sems/event_detail/2015_weig

hing

August 27 (2 hr)

Webinar ‐ Document Control and Record

Keeping

2:00 p.m. ‐ 4:00 p.m.

Class No. 5335

September 14 ‐ 17

NEMAP**

Class No. 5359

Massachussetts

September 24 (2 hr)

Webinar ‐ State Laboratory Annual Submis‐

sion Process

Class No. 5355

September 27 ‐ October 1 (5 days)

Western Weights and Measures Association

(WWMA)

Boise, ID

Contact: Jerry Buendel, 

jbuendel@agr.wa.gov

September 28 ‐ October 1 (4 days)

SWAP**

Class No. 5360

Missouri

October 5 ‐ 7

Central Weights and Measures Association

(CWMA) Interim Meeting

St. Charles, MO

Contact: Sherry Turvey,

sherry.turvey@kda.ks.gov

October 5 ‐ 8 (4 days)

MidMAP**

Class No. 5361

Wisconsin

October 19 ‐ 23 (5 days)

HB 133, “Checking the Net Contents of Pack‐

aged Goods,” Basic

Class No. 5346

Frankfort, KY

October 22 (2 hr)

Webinar ‐ Internal Auditing Best Practices

2:00 p.m. ‐ 4:00 p.m.

Class No. 5339

October 26 ‐ November 6 (2 weeks)

Mass Metrology Seminar

Class No. 5340

NIST/Gaithersburg

(continued pg 6)

Note: Error weights or an expanded scale resolution feature, providing the

scale is equipped with one, may be used to expand the readability of a scale

to a value smaller than “d.” If readability can be expanded, it is the value to

which a scale can be read that should be inserted for the value of the scale

division “d” in formulas (1) and (2) shown above. For example, in formula (1),

if d = 0.02 lb and the scale can be put into an expanded resolution and read

to 0.002 lb, then it is 0.002 lb, rather than 0.02 lb, that is to be less than or

equal to one‐tenth the smallest applied tolerance. 

In consideration of these two formulas, it is important to be mindful of the

relationship between the value of “d” on the reference scale and the mini‐

mum test draft size. Increasing the size of the smallest test draft allows for

the use of a reference scale with a higher scale division value. Stated differ‐

ently, as the value of the scale division increases on the reference scale, so

must the size of the smallest test draft. 

Accessing Mass Units. CNG RMFDs are required to indicate the delivered

quantity in either gasoline gallon equivalent (GGE) units or gasoline liter

equivalent (GLE) units as specified in Mass Flow Meters code paragraph

S.1.3.1.1. Compressed Natural Gas Used as an Engine Fuel. Even though they

must indicate in GGE or GLE units, the dispensers are required to display the

mass measured for each transaction. The mass value may either be displayed

continuously on an external or internal display accessible during the inspec‐

tion and test of the dispenser, or the mass value may be accessed using con‐

trols on the device as specified in paragraph S.1.2. Compressed Natural Gas

Dispensers. 

S.1.3.1.1. Compressed Natural Gas Used as an Engine Fuel. – When

compressed natural gas is dispensed as an engine fuel, the delivered quantity shall be indicated in “gasoline liter equivalent (GLE) units” or “gasoline gallon equivalent (GGE) units” (see definitions).

(Added 1994)

S.1.2. Compressed Natural Gas Dispensers. – Except for fleet sales

and other price contract sales, a compressed natural gas dispenser used to

refuel vehicles shall be of the computing type and shall indicate the quantity, the unit price, and the total price of each delivery. The dispenser shall

display the mass measured for each transaction either continuously on an

external or internal display accessible during the inspection and test of the

dispenser, or display the quantity in mass units by using controls on the

device.

(Added 1994)

SECTION 3.37. MASS FLOW METERS CODE PARAGRAPHS S.1.3.1.1.

COMPRESSED NATURAL GAS USED AS AN ENGINE FUEL AND S.1.2.

COMPRESSED NATURAL GAS DISPENSERS

It is wise to determine how mass units are accessed in advance of arriving on

site for a test so that if special assistance or some separate piece of equip‐

ment is needed to access the mass units, these can be made available at time

= Smallest test load (2) Reference scale division (d) x 10

Tolerance of device under test
W&M Connection 6 Volume 5 Issue 7

of test. Some NTEP Certificates of Conformance (CCs) provide an indication

of how mass units can be accessed. If not specified on the CC, the device

owner should be able to provide this information. 

Test Equipment Information

Given the limited number of CNG refueling stations in some areas of the coun‐

try, combined with the uncertainty of knowing just how many more might be

added in the future, some states are finding it difficult to justify the expense

of purchasing the test equipment needed to test CNG RMFDs. As an alterna‐

tive to purchasing the test equipment, some states are currently opting to re‐

quire, under the provisions of NIST Handbook 44 paragraph G‐UR.4.4.

Assistance in Testing Operations, that the owner or operator of the dispensers

supplies the specialized test equipment. 

G‐UR.4.4. Assistance in Testing Operations. – If the design, con‐

struction, or location of any device is such as to require a testing

procedure involving special equipment or accessories or an ab‐

normal amount of labor, such equipment, accessories, and labor

shall be supplied by the owner or operator of the device as re‐

quired by the weights and measures official.

NIST HANDBOOK 44 PARAGRAPH G‐UR.4.4. ASSISTANCE IN TESTING

OPERATIONS

Whether provided by the jurisdiction or the device owner, the following test

equipment is needed to perform an official test on a CNG RMFD: 

• Test cylinder – the container (or vessel) that receives the test drafts of

CNG that are dispensed during the testing of a CNG RMFD. 

• Reference scale – the scale used to determine the actual weight of the

CNG delivered into the test cylinder for each test draft.

• Test weights ‐ physical standards that meet specifications and toler‐

ances in NIST Handbook 105‐series handbook (or other suitable and

designated standards) that are used to test and determine the ade‐

quacy of the reference scale prior to it being used as a transfer stan‐

dard in the testing of a CNG RMFD. Test weights of smaller value,

known as “error weights” are sometimes needed to reduce rounding

errors and expand the readability of a digital electronic reference scale

so that it can be read to a value less than its displayed scale division.

Test Cylinder

NIST EPO N0. 28 Examination Procedure Outline (EPO) for Compressed Nat‐

ural Gas (CNG) Retail Motor Fuel Dispensers provides a list of criteria officials

need to verify concerning the test cylinder. The EPO indicates that the fol‐

lowing should be considered when selecting a test cylinder: 

• rating must be equivalent to or greater than the service pressure*

marked on the device under test as required by the ANSI/IAS NGV

4.1/CSA 12.5 “NGV Dispensing Systems,” Standard for Natural Gas Ve‐

hicle Dispensing Systems;

• compatible fittings that allow for the connection of the dispenser dis‐

2016

January 9 ‐ 4

National Conference on Weights and Meas‐

ures (NCWM) Interim Meeting

San Diego, CA

No information available at this time.

February 11 (2 hr)

Webinar ‐ Conducting an Effective Management

Review

2:00 p.m. ‐ 4:00 p.m.

Class No. 5336

March 3 (2 hr)

Webinar ‐ Internal Auditing Best Practices

2:00 p.m. ‐ 4:00 p.m.

Class No. 5337

*Invitation Only

**Limited to State Laboratory Program Par‐

ticipants

HANDBOOKS SHOULD HAVE ARRIVED

AT A MAILBOX NEAR YOU.

NIST Handbook 130 (2015), Uniform Laws and

Regulations in the Areas of Legal Metrology

and Engine Fuel Quality.

NIST Handbook 133 (2015), Checking the Net

Contents of Packaged Goods.

NIST Handbook 44 (2015), Specifications, Tol‐

erances and Other Technical Requirements for

Weighing and Measuring Devices.

Handbooks have been shipped based on the

information provided by the National Confer‐

ence on Weights and Measures (NCWM).

Membership who have requested handbooks

should have received them. Those that re‐

newed their memberships early will receive

their copies first. If you have any questions,

you can contact NCWM at info@ncwm.net.

Also note that these documents are available

online free of charge at the NIST, Office of

Weights and Measures website at:

http://www.nist.gov/pml/wmd/index.cfm

See the links under “Popular Links” in the

lower right hand column.
W&M Connection 7 Volume 5 Issue 71

charge nozzle;

• bleed valve;

• pressure gauge;

• drain hose; and

• means for grounding the cylinder prior to connecting to dispensing

equipment such as a quick connect ground strap.

*Note: Service pressure is the settled pressure at a uniform gas temper‐

ature of 21 o

C (70 oF) and full gas content. It is the pressure for which

the equipment has been constructed under normal conditions. This is

different from the maximum working pressure.

In addition to verifying that a test cylinder complies with all the criteria listed

in the NIST EPO, the capacity of the test cylinder (i.e., the amount of CNG it

will contain) is needed to determine whether or not it is of sufficient capacity

to be considered suitable for use in testing the particular RMFDs that are

planned. In order to be considered suitable, the test cylinder must be able

to hold at least three times the value of the minimum measured quantity

(MMQ) marked on the dispenser for the following reasons: 

• MMQ is an operational rating declared by the manufacturer of the

equipment and provides an indication of smallest quantity that can

be accurately measured by the device. This rating applies to both use

and testing of a device. Thus, it would not be appropriate to dispense

an amount less than the MMQ for any tests intended to verify accu‐

racy of the device; nor would it be appropriate for an operator to dis‐

pense a quantity less than the MMQ. 

• A segment of the overall test to verify accuracy of a CNG RMFD, as

outlined in EPO NO. 28, requires the completion of three consecutive

test drafts, each equal to one‐third test cylinder capacity. The first

test draft is dispensed into the empty test cylinder. The second and

third test drafts are initiated with product from the previous test

draft(s) remaining in the test cylinder. The test cylinder should be full

after completion of the third test. Since it would not be appropriate

for any test draft to be less than the MMQ, the test cylinder needs to

be able to hold at least three times the value of the MMQ to accom‐

modate proper completion of these three consecutive, one‐third ca‐

pacity tests. 

Reference Scale

Aside from having to test a reference scale to prove its adequacy prior to

using it as a transfer standard, there are four important questions relating

to elements of scale design that need to be answered to determine whether

or not a reference scale is adequate. 

1. Is it intrinsically safe?

2. Is the value of the scale division small enough that rounding errors

won’t use up too much of the tolerance to be applied to the device

under test?

3. Is the capacity large enough to weigh a test cylinder full of product?

4. Does its design accommodate ease of application and proper posi‐

tioning of the test cylinder during testing?

NATIONAL CONFERENCE

ON WEIGHTS AND MEASURES

2015

INTERIM MEETING

JANUARY 18 ‐ 21, 2015

DAYTONA BEACH, FLORIDA

Registration and lodging information for the

January meeting is available online at:

https://www.ncwm.net/sems/event_detail/2

015_interim_fl. 

The meeting schedule and supporting docu‐

ments are also available at this website loca‐

tion.

Hotel Accommodations:

Group Code: NCWM15

Hilton Daytona Beach Oceanfront Resort

100 North Atlantic Avenue

Daytona Beach, FL 32118

Phone: (386) 947‐8016

Fax: (386) 944‐1394

or online at:

http://www.hilton.com/en/hi/groups/person‐

alized/D/DABDHHF‐NCWM15‐

20150115/index.jhtml

Let Your Voice Be Heard!

VISIT THE NATIONAL FIRE PRO‐ TECTION ASSOCIATION FOR VALUABLE

TIPS ON CHRISTMAS SAFETY.

http://www.nfpa.org/categoryList.asp?catego‐

ryID=296&URL=Safety%20Information/For%20c

onsumers/Holidays/Christmas%20tree%20fires&

cookie%5Ftest=1

Artifical trees should be labeled, certifed, or

identified by the manufacturer as fire retar‐

dant.
WEIGHTS AND

MEASURES

IN THE NEWS

Ahwatukee Foothills News

Check those receipts, save money this

holiday season

http://www.ahwatukee.com/holly/article_8

0014444‐74eb‐11e4‐a9bd‐

3f1dab93abf3.html

CBS SF Bay Area

Caught on Video: Gas Pump in Castro

Valley Keeps Charging Customer After

Filling Tank

http://sanfrancisco.cbslocal.com/2014/

11/29/caught‐on‐video‐gas‐pump‐in‐

castro‐valley‐keeps‐charging‐customer‐

after‐filling‐tank‐overcharged‐gas‐statio

n‐redwood‐road‐weights‐and‐mea‐

sures/

Poway Patch

Shop Smart, Shop Carefully

http://patch.com/california/poway/sho

p‐smart‐shop‐carefully‐0

Springfield News‐Leader

Know the facts before buying, or sell‐

ing, firewood

http://www.news‐

leader.com/story/news/business/2014/

11/29/know‐facts‐buying‐selling‐fire‐

wood/19673477/

Atlantic Highlands Herald

Monmouth County Checking Fuel Oil

Trucks for Accuracy

http://www.ahherald.com/newsbrief/m

onmouth‐news/18871‐monmouth‐

county‐checking‐fuel‐oil‐trucks‐for‐ac‐

curacy

AGRI‐VIEW

Black Friday: Hit the stores with a plan

http://www.agriview.com/news/re‐

gional/black‐friday‐hit‐the‐stores‐with‐

a‐plan/article_86a6a02c‐9c9b‐5c0c‐b3d

1‐4a1997d68057.html

W&M Connection 8 Volume 5 Issue 7

The following provides a discussion of these questions and explains their

significance in determining the adequacy of a reference scale. 

• Intrinsically safe? NIST EPO NO. 28 provides the following guid‐

ance on intrinsic safety as it relates to a reference scale: scale meets Un‐

derwriters Laboratories (UL) Area Classification Class I Division 2 Group D

(scale equipment must be located outside of the classified area, which is five

feet from the hose fueling connection to the dispenser). It’s important to

confirm that the reference scale complies with the UL standard specified

due to the high flammability of CNG.

• Is the value of “d” small enough? As explained earlier in the section

of this article titled “The RMFD,” the value of “d” is small enough

when the scale can be read to a value that is less than or equal to

one‐tenth the tolerance to be applied to the RMFD. Therefore, to de‐

termine if scale resolution is appropriate, one only needs to know the

value to which the reference scale can be read; the tolerance to be

applied to the RMFD during testing; and the MMQ marked on the dis‐

penser. If the scale is to be setup and used outdoors, it’s also a good

idea to determine if shielding will be made available to reduce the

effect of wind. 

• Is the scale capacity large enough? The scale selected for use must

have a capacity large enough to weigh a test cylinder full of product

including the weight of any shims, cart, or other accessory items that

will likely be applied to the scale when weighing the test cylinder dur‐

ing testing. Therefore, one must have knowledge of the approximate

weight of the empty test cylinder selected for use in testing and also

the approximate weight of the CNG that it will contain when full.

When added together, the result equals the approximate weight of

the test tank full of product. In some cases, the supplier of the test

cylinder may be able to provide the approximate weight of the cylin‐

der full of product. If not, he or she should be able to provide the

approximate weight of the test cylinder empty and the volume ca‐

pacity of the test cylinder in GGEs or GLEs. The volume capacity of

the test cylinder can be converted into weight by multiplying the vol‐

ume capacity value by its associated conversion factor (5.660 lb for a

volume capacity specified in GGEs and 0.678 kg for a volume capacity

specified in GLEs) to determine the capacity of the test cylinder in

units of weight. The approximate weight of a test tank full of CNG

may then be determined by adding the weight of the empty test cylin‐

der to that of the CNG contained in a full test cylinder. 

• Does its design accommodate ease of loading and proper position‐

ing of the test cylinder? Determine the approximate weight of the

test cylinder in an empty state and when full of CNG to gain a better

understanding of the amount of weight to be moved and hoisted onto

the scale. Determine the type of scale selected for use and the ease

with which the test cylinder can be safely applied to the load receiving

element, both when empty and when full of CNG. Confirm that

when the test cylinder is positioned on the scale for weighing, the

load is distributed evenly over the main load supports of the scale
W&M Connection 9 Volume 1 Issue 1

and does not produce binding or off‐center loading. A preliminary determination of whether or not scale design

accommodates ease of loading and proper position of the test cylinders can be made based on a comparison of the

type of reference scale used, size test cylinder and its weight when full of product. 

Test Weights

Based on a NIST OWM recommendation that reference scales used in the testing of CNG RMFDs be tested to at least the

weight of the largest test draft of CNG to be weighed, the weight of the test cylinder full of product must be known to de‐

termine the minimum amount of test weight that will be needed to test the reference scale. NIST Class F standards are

generally of sufficient accuracy to test a reference scale that will be used to weigh test drafts of CNG dispensed from a

RMFD. 

Summary: When planning for the test of a CNG RMFD, it is always a good idea to obtain the information necessary to de‐

termine whether or not the different test equipment made available for testing will be adequate. This article was developed

to assist in identifying the information that is needed and explain how that information is used to make this determination.

Verifying in advance that the equipment being supplied is suitable improves the likelihood that testing can be safely com‐

pleted and with confidence at the time scheduled. For additional information regarding this article, please contact Rick

Harshman at richard.harshman@nist.gov or by phone: (301) 975‐8107.

U.S. National Working Group on Alternative

Test Methods, Field Task Group Activities

Byline: G. Diane Lee

The National Institute of Standards and Technology (NIST), Office of Weights and Measures established the U.S. National

Working Group (USNWG) on Alternative Test Methods (ATMs) for Commercial Measuring Devices. The objectives of the

USNWG on ATMs are to promote, encourage, and participate in the establishment of a comprehensive set of standards;

encourage their widespread use by weights and measures officials and service companies to test commercial measuring

devices; and establish proposed alternatives to ensure that the methodologies and standards facilitate measurements that

are traceable to International Systems of Units (SI). This work includes an investigation of current methodology and stan‐

dards (e.g., neck‐type volumetic field standards and associated test procedures). At its initial April 2012 meeting, a field

task group was established to look at areas in which work is needed to establish the framework for recognizing a given al‐

ternative test method for commercial use. At this meeting the field task group identified the areas of work needed to es‐

tablish this framework:

• uncertainty analysis of test methods used in the field;

• protocols (framework, key issues and questions to be answered);

• legal and acceptance issues (references in laws and regulations and service companies vs. weights and measures

regulations); and

• field inspection (Evaluation Procedure Outlines (EPOs), guidelines, training, variables in field implementation).

The field task group began working to identify and quantify uncertainties associated with testing liquid measuring devices

by:

• reviewing the key factors that contribute to measurement uncertainty when using hand held test measures, bottom

drain provers, and closed loop provers; and

• developing a test protocol for side‐by‐side testing of retail motor fuel dispensers using test measures, bottom drain

provers and closed loop provers.

In May 2013, side‐by‐side tests were conducted at two different retail motor‐fuel stations in Pennsylvania. Three fuel types

(regular, premium, and diesel) were tested on a total of 18 positive displacement (PD) meters; including 4 diesel and 14
W&M Connection 10 Volume 1 Issue 1

gasoline meters. A maximum of five fast and two slow flow tests were performed on each meter and product. Prior to

testing, NIST technical advisors verified that each standard used for testing had a current calibration certificate.

The analysis of the side‐by‐side test results was based on a limited number of data points and test conditions and, as such,

was not intended for use to draw any final conclusions regarding the suitability of the standards examined or the effects of

any factors contributing to uncertainties associated with the use of a given standard. The data associated with the analysis

were intended to assist the USNWG in its efforts to determine baseline values for assessing the uncertainties associated

with testing using three different types of standards. 

After the side‐by‐side test data was analyzed, NIST, OWM learned that the validity of the calibrations that were performed

in another state on the test measure and bottom drain prover could not be confirmed due to traceability issues. Without

a valid calibration to provide a correct value and uncertainty for these standards, no determination could be made to how

well the methods compared to each other (e.g., the bias between standards could not be determined). However, the field

task group was able to review the repeatability for each of the standards separately. 

The task group met to review the data. Outliers were observed that revealed possible problems with the repeatability for

two of the standards. More data is needed to draw any final conclusions of repeatability problems. It was agreed that

more data is needed to review the operation of the standards over wider ranges of temperature, time, and flow in addition

to other major factors that contribute to uncertainties of tests using different standards. As such, the ATM field task group

identified the major contributing factors to uncertainties associated with the alternative test methods examined:

• repeatability over a range of temperatures and time;

• repeatability over a range of flow rates and time;

• vapor loss;

• effects on test results due to removing the dispenser nozzle for testing; and

• compressibility.

It was also noted during this meeting that existing data is available that may be used to assess the uncertainty of alternative

test methods used in the field. Following the meeting, field task group participants provided data that was collected from

other studies, along with a summary of challenges and concerns. NIST summarized this information in a matrix and dis‐

tributed it to the field task group. 

The matrix lists the major contributing factors to uncertainties associated with the alternative test methods as noted above

in this article and groups the uncertainty data that was submitted with the major contributing factor that it supports. The

list is color coded to denote if the data was provided from a source outside the task group, collected as part of the field

task group activities, or if specific data is still needed. In addition, the matrix includes (1) who provided the data; (2) chal‐

lenges to the data; (3) comments; and (4) notations of whether or not uncertainty values are included in the analysis of the

data. Due to the number of concerns and challenges to the data, it was determined that additional data are needed to ad‐

equately quantify uncertainties for the major contributing factors identified by the field task group. 

Volunteers are needed to assist manufacturers in collecting the data needed to complete the uncertainty analysis for testing

using different standards. As additional data is collected and pending sufficent resources, NIST will monitor and witness

the data collection as resources are available to assist the field task group in its efforts to determine the uncertainties as‐

sociated with alternative test methods. 

The field task group will need to develop guidelines to ensure that the data collected is appropriate and valid for use in de‐

termining the uncertainties associated with the different test methods. If you have any questions about this work or the

work of the field task group, please contact Diane Lee by e‐mail at diane.lee@nist.gov.