Publications

81-2296

AlllOb DMflMSM

Criteria and Evaluation for

Two-Step Flush Devices for Water Closets

Fred Winter

Lawrence S. Galowin

Center for Building Technology

National Engineering Laboratory

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

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81-2296

1981

ne 1981

NBSIR 81-2296

CRITERIA AND EVALUATION FOR

TWO-STEP FLUSH DEVICES FOR WATER CLOSETS

HATlOitAL BURRA U

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JUL -2 0 1981

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Fred Winter

Lawrence S. Galowin

Center for Building Technology

National Engineering Laboratory

U.S. Department of Commerce

National Bureau of Standards

Washington, DC 20234

June 1981

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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TABLE OF CONTENTS

Page

PREFACE

ABSTRACT .

1. INTRODUCTION I 1.1 Background . 1

1 .2 Description of Two-Step Flush Devices 1 1.3 Project Objective and Purpose 2

1 .4 Project Scope and Approach 2

2. RATIONAL AND FRAMEWORK FOR TESTING TWO-STEP FLUSH DEVICES 3

2.1 Hydraulic Requirement - Siphonic Action 3

2.2 Trap Seal Retention 5 2 .3 Water Exchange 5 2.4 Rim Wash 6

2.5 Paper Removal 6

2.6 Mechanical Performance 6

3. TEST METHODS 8

3.1 Test Samples 8

3.2 Test Sequence 8

3.3 Test Equipment and Apparatus 9

3.4 Laboratory Tests 9

4. DISCUSSION OF THE LABORATORY TEST RESULTS 19

4.1 Characteristics of Water Closet Bowls 19

4.2 Test of Siphonic Action and Trap Seal Retention 23

4 .3 Water Exchange Test 32

4.4 Test of Paper Removal 48

4.5 The Rim Wash Test 48

4.6 Tests of the Two-Step Flush Devices 53

5. RECOMMENDED CRITERIA AND TESTING PROCEDURES FOR TESTING

TWO-STEP FLUSH DEVICES FOR SIPHONIC WATER CLOSETS 59

5.1 Categories of Two-Step Flush Devices 59

5.2 Criterion for Two-Step Flush Devices 60

5.3 Test Equipment and Apparatus Set Up 61

5.4 Testing Procedures 62

6. CONCLUSIONS, RECOMMENDATIONS AND FUTURE RESEARCH PROSPECTIVES 70

6.1 Conclusions 70

6.2 Recommendations 70

6.3 Research 71

7. REFERENCES 72
TABLE OF CONTENTS (CONTINUED)

Page

APPENDIX 74

A. DESCRIPTION OF TWO-STEP FLUSH DEVICES 74

B. MATERIAL RELATED TO THE WATER EXCHANGE TEST 79

B.l Detection of Color in the Water Closet Bowl by Visual

Examination 79

B.2 Comparison of Values of "R" as Resulted from Different

Initial Concentrations 81

B.3 Water Exchange Test-Errors in Measuring Sodium Bromide

Solutions 81

B.4 Derivation of the Equation for Water Exchange 82
LIST OF TABLES

Page

TABLE

1 Characteristics of water closet bowls 20

2a-2f Test for siphonic action and trap seal retention 24-29

3 Occurrence of siphonic action at successive applications of

partial flush cycles 30

4 Values for Vp and Ver for two w.c. samples 31

5 Granule test results for partial flush cycles 33

6a-6f Concentration ratios of sodium bromide in the w.c. well

before and after flushing 35-40

7 Water exchange — relative concentration values for European

water closets 42

8a, 8b Concentration ratios before and after flushing comparison between

laboratory data and results obtained by empirical equation 46,47

9 Test of paper removal 49

10 Rim wash test - experiments with three methods 50

11 Rim wash test - the ink test 52

12a-12d Summary of tests carried out with the two-step flush devices 55-58

13 Consistency of water delivered in a full and partial flush

cycle 67

14 Test for siphonic action and trap seal retention 68

15 Liquid wastes removal — water exchange test 69

16 Detection of color in the water closet bowl by visual

examination ' 79

17 Comparison of "R" value results from different initial

concentrations 80

18 Water exchange test - errors in measuring sodium bromide

solutions 81
LIST OF FIGURES

Figure Page

1 Siphonic water closet bowl 4

2 Siphonic action in a water closet bowl 4

3 Test equipment and apparatus 10

4 Ball cock flow rate in time for three water closet 21

5 Flow rate from water closets 22

6 Relative concentration ratio "R" as a function of water use

in the flush cycle (laboratory test data) 41

7 Water exchange test-empirical equation and laboratory results ... 47

8 Two-step flush device - Sample 74

9 Two-step flush device - Sample 75

10 Two-step flush device - Sample M-j 76

11 Two-step flush device - Sample 77

12 Two-step flush device - Sample 78

iii
PREFACE

This report is one of a group documenting National Bureau of Standards (NBS)

research and analysis efforts in developing water conservation test methods,

analysis economics and strategies for implementation and acceptance. This

work is sponsored by the Department of Housing and Urban Development/Office

of Policy Development and Research in the National Bureau of Standards (NBS)

Water Conservation projects under 11UD Interagency Agreement H-48-78.

Certain trade names and company products are identified in this report.

In no case does such identification imply that the products are necessarily

the best available for the purpose for which they were mentioned.

IV
ABSTRACT

Laboratory tests of two-step flush control devices for water closets were

conducted to provide data and develop test methods for evaluating water saving

devices for water closets. Criteria for performance and testing procedures

for laboratory testing are recommended for evaluating two-step flush devices

for installation in conventional water closets.

Key Words: dual flush toilets; low flush toilets; water conservation;

water closets

v
CRITERIA AND EVALUATION OF TWO-STEP FLUSH DEVICES FOR WATER CLOSETS

1. INTRODUCTION

1 .1 Background

Surveys of residential water usage patterns in the United States indicate that

the water consumption per capita per day ranges from 150 liters (40 gallons) to

260 liters (70 gallons) [1,2,3]. Most studies indicate that the water closets

use from 30 to 45 percent of the total household consumption. Therefore, water

conservation measures focus primarily on the water closet for the reduction of

the total residential water usage and also for the reduction of the total

wastewater influents to the wastewater processing systems. At present, various

water conserving toilets are available; they are classified as "zero discharge

toilets," such as vacuum toilets and macerator toilets, which require less than one gallon per usage. The major manufacturers market "water saving" toilets

which consume 13 liters (3.5 gallons) per flush cycle as compared to the

ordinary toilets which require 20 liters (5.5 gallons) per flush cycle. Most

water-saving water closets do not have any unique features in comparison to the

ordinary toilets. These water closets contain supply tanks which are either

smaller or contain flush valves which are designed to deliver a smaller quantity

of water to the bowl. Some manufacturers modified the design of the bowl to

facilitate a reduction in the water usage. Various techniques have been used

in order to reduce the water consumption of the toilets. Well known methods

are the bricks and bottles placed in the tank to displace the volume of water

that otherwise would have been flushed down. Dams are other well known

manufactured devices which are placed in the toilet tank and retain water in

the bottom section of the tank from being flushed out.

1.2 Description of Two-Step Flush Devices

The two-step (or multi-step) flush mechanism is a device inserted in the toilet

tank and replaces the ordinary flush valve. The device enables the user to

selectively operate the toilet tank so that the nominally full quantity of

water will be delivered to the bowl or a partial quantity, depending on the

choice of the user. Selection between the two quantities of water is made by

either having two distinct flush handles or one handle which can be rotated

clockwise and counterclockwise so that each handle or direction actuates a different part of the mechanism to control and deliver the desired quantity

of water to the bowl. A partial flush cycle is attained by an earlier closure

of the flush valve which stops the flow of water to the bowl and retains part

of the water in the tank. The design and operation of the devices evaluated

in this project are described in Appendix A.

Two-step flush mechanisms have been used in Europe for over four decades and

have provided adequate performance. The European flush down toilets ordinarily

require 9-10 liters (2.4 - 2.6 gallons) for a full flush and 4.5 - 5.5 liters

(1.2 - 1.4 gallons) for the partial flush normally used for the flushing of

urine and light solid matter. A survey in England [4] indicated a substantial

reduction of water consumption when dual flush devices were used. However,

contrary to the European flush down toilets, for which two-step flush devices

1
in siphonic water closet bowls used in this country is less readily applicable.

In the United States, the water closet bowls operate on the principle of

siphonic action which is more complex as compared to the operation of the

European Flush Down toilets which operate by a weir overflow action. The

design of a two-step device for siphonic bowls requires additional considerations. The American siphonic bowl consumes large quantities of water. Since

this toilet type is still a standard fixture in this country and is expected to

remain so in the immediate future, the development of two-step flush devices is

highly desirable since they have the potential of a 40 percent saving of the

toilet water consumption and 15 percent saving of the total household water

consumption. This report presents the results of the investigation and laboratory testing of two-step flush devices. The laboratory work also included

tests on siphonic water closets for evaluating their performance for two modes

of flush cycles as they are required to be operated when two-step flush devices

are installed in the water closet tanks.

1 .3 Project Purpose and Objectives

The purpose of this investigation is to establish a basis for objective evaluation of the performance of two-step flush devices designed for the reduction of

the water consumption of water closets. The objectives are to develop a methodology, testing procedure, and criteria for evaluating the functional

adequacy of two-step flush mechanisms, and recommend the implementation of this

material into standards.

1 .4 Project Scope

The laboratory work included tests for investigating the effects of reduced

water usage such as occur with two-step flush devices on the following aspects:

Hydraulic operation of the water closet

- Sanitary requirement

Mechanical functions of the two-step flush mechanism

2
2. RATIONALE AND FRAMEWORK FOR TESTING TWO-STEP FLUSH DEVICES

The criteria for evaluating the two-step flush devices were established on the

basis of existing standards for sanitary fixtures [5, 6, 7, 8, 8], and on a rationale based on the elementary functions which two-step flush systems are designed to perform. These requirements include the following elements:

- Siphonic action

- Retention of the trap seal in the water closet

- Adequate removal of the liquid wastes from the bowl

- Adequate cleansing of the surfaces of the bowl

- Adequate removal of paper wastes from the bowl

Satisfactory mechanical operation of the mechanism of the two-step flush

device

2.1 Hydraulic Requirement - Siphonic Action

The conventional American water closet operates on the principle of siphonic

action. The hydraulic operation of the water closet is directly related to its

functional performance since the occurrence of a siphonic action in the bowl

during the flush cycle is the predominant factor for an adequate performance of

the bowl. The flush cycle in a siphonic bowl is described by the following

three stages: (see Figures 1 and 2)

Stage 1 - Water flows from the tank and enters the bowl through the rim and jet

orifices. At this stage, the mode of flow through the trap and down

leg is by weir action as the water overflows the weir crest.

Stage 2 - As the sheet of water flows down the weir, air is carried along, and

the bend in the down leg prevents the entrance of new air to the

bowl. Partial vacuum is created in the waterway, and a full bore

flow takes place in the bowl.

Stage 3 - As supply diminishes, the water level in the bowl drops to nearly the

bottom of the trap, air enters the trapway, and the siphon breaks.

H^ in Figure 2 represents the available energy during the weir flow stage (plus

a small additional velocity head due to the rim jets flow) and H

g

, the available

head during the siphon action. H

g is far greater than Hy Therefore, the flow

rate and consequently the cleansing action of the bowl takes place primarily in

the second stage, while the flow in the first stage does not contribute to the

performance of the bowl, and merely serves for priming the siphon. The second

stage requires a relatively large amount of water for maintaining the siphon

action and evacuating the contents of the bowl. These observations describe

the operation of a siphonic water closet from which the following definition

was formulated:

3
Water = Supply - "jKito.Orif ices

0 Brain

S Siphonw Weir rGres

Down f,eg of ‘Siphon

j ;Ttap=Seal iHeigh t TT

£, Dip

- :Trap i Jet1 rQtfif ice

Figure 1. Siphonic water-closet cbdvl

Hw - Weir Head Hg - Head of Siphon

? .First LStage 1 Second t&teage

' 1 Heir Flow -Developted iSiphonic (Action

T Third Stage

B Breaking' fo f ; 'th& iSiphon

- Figure 2. Siphonic action in a nsiphoni© water closet-bowl

4
"A fully developed siphonic action: is that mode of flow in the bowl described

in the above three stages, and in the final stage the water level in the bowl

drops below the dip of the bowl.

With a reduced quantity of water a "fully developed siphonic action" may not

take place in the flush cycle which in turn, may result in a sharp reduction of

the performance of the bowl. The tests (described later) indicate that this is

indeed the case, and the siphonic action in the bowl is important even for the

removal of liquid wastes and light matter such as toilet paper.

2 .2 Trap Seal Retention

The function of the trap seal is the prevention of foul air and gases from

flowing from the sewer back to the fixtures and the utility room, and is a universal requirement for all sanitary fixtures and appliances. The trap is

either an integral part of the fixture or must be connected between the fixture

and the drain pipe. For water closets, the requirement for the trap height

vary from 50 mm (2 in) to 75 mm (3 in), depending on the water closet type. In

reference to the preceding description one notes that the bowl remains nearly

empty upon termination of siphonic action. The bowl is refilled by the ball

cock through its refill tube which draws part of the water flowing to the tank

and directs the water to the bowl. A well-designed refill arrangement is such

that the bowl is filled to its weir upon termination of the flush cycle. No

water should overflow the weir since any quantity of water overflowing the

weir is a waste. A partial flush with a two-step flush mecanism cuts the time

of fill and consequently reduces the volume of water refilling the seal trap.

It is therefore anticipated that complete replenishment of the seal trap will

not always be attained. From a sanitary standpoint, complete restoration of

the trap seal is not mandatory since a trap seal level of any magnitude will

prevent the backflow of foul gases from the sewer line. However, some minimal

trap seal is required as a guard against a complete depletion of the trap

because of excessive pressure excursions which may take place in the drains and

affect the traps, and because of water evaporation which may take place if the

toilet is not being used for a period of several days [9, 10]. A procedure is

therefore required to test the integrity of the trap seal when the toilet is

flushed with reduced water quantities when two-step flush devices are installed.

2 .3 Water Exchange

The incoming water from the tank should replace the contaminated liquid wastes

removed from in the bowl. This requirement is important for sanitary and

aesthetic reasons. Aesthetically, liquid wastes and residues affecting the

clarity of the water in the bowl are undesirable; however, the degree of detection is highly subjective as demonstrated in a limited survey done at the NBS

laboratory (see Appendix B, Table 15). It is safely assumed that the "slight"

coloration of the bowl is of little importance, and is only secondary to the

sanitary aspects. From a sanitary standpoint, residues of liquid wastes are undesirable. Several studies [11, 12] report on bacteriological contamination

of plumbing fixtures. Tests on toilets indicate that the degree of contaminants

removal is directly dependent upon the quantity of water used in the flush

cycle. It is fairly obvious that the more water used per flush, the less

5
residual contaminants remain in the toilet bowl. However, from the health and

microbiological point of view, no investigation has demonstrated the correlation

between the degree of unflushed contaminants, of any form, in the bowl, i.e.

particulates from fecal matter, toilet paper, or urine, to the actual disease

transmission by pathogenic organisms. Due to the lack of any medical information, it is difficult to establish the sanitary requirements or determine a "safe" or "critical value" of the contaminants allowed to remain in the bowl

after the flush cycle. In the Sixth Draft of ANSI 112.1M-1980 [5], it is stated

that "a dilution ratio of at least 100 shall be obtained in each initial flush;"

however, it has not been demonstrated whether this value is sufficiently low

and safe from the sanitary aspect. The effect of the waste matter residual

bacteriological parameters in the bowl is not known and remains to be evaluated

by other methods. The objective of this project is to establish a test procedure

for determining with a reasonably high degree of accuracy the dilution ratios

which occur with reduced quantities of flush water. The improved levels of

detection for very small concentration of residuals provide a step forward

toward the resolution of the water exchange requirements.

2 .4 Rim Wash Test

Unwashed surfaces in the bowl may create, in time, zones of bacterial growth

and foul odor. Information on the long-term effects of imperfect rim wash is

not available. With reduced flows which occur in partial flush cycles, the

effectiveness of the rim wash may be somewhat reduced. However, the purpose of

the partial flush cycle is only t > remove liquid wastes and "light matter" so that the requirements of the rim wash test for partial flush cycle may be less

stringent in comparison to the full flush cycle. Furthermore, since a partial

flush cycle will eventually be followed by a full flush cycle, the long-term

effects are probably minimal as long as an adequate rim wash is attained with a full flush cycle.

2 . 5 Paper Removal

Under reduced quantity of flush, it is expected that the water will evacuate

the paper load "normally used" after urination. This requirement probably stems

from aesthetic reasons, though other liquid excretions soaked in the paper waste

may have sanitary hazards. It follows that a test is required to evaluate and,

if possible, to quantify the efficiency of the water closet in removing paper

wastes under reduced flows.

2 .6 Mechanical Performance

Two-step flush devices have not been designed and installed by water closet

manufacturers. The devices have been manufactured and marketed by firms which

deal with related equipment and devices for sanitary appliances and water

conserving devices. As inserts to existing systems, the following needs should

be satisfied:

Compatibility of the device with existing toilets in terms of installation

and operation

6
Capability in adjusting the controls for the desired quantities of water

will be flushed with a sufficient degree of consistency

Sound construction and durability of parts

No interference with existing mechanises

7
3 . TEST METHODS

The following procedures and laboratory test methods were established to

evaluate the performance of water closets when modified to function as two-step

flush systems by the insertion of the two-step flush devices. The findings of

these tests provided information for formulating the test procedures of twostep flush devices.

3 .1 Test Samples

Six water closet samples were selected from catalogues of the major manufacturers

from types and models most widely used throughout the country. A product search

for the two-step devices yielded five systems for evaluation.

For identification purposes, the samples were marked and tested as follows:

Water Closets:

®1 » A3 » , C

3

, , K

3

Samples , A^ , Cc are nominally 5 gallon water closets. Samples A

3

, C

3

, K

3 are nominally 3 1/2 gallon water saving closets.

Two-Step Flush Devices:

M1# M

2

, M

3

, M

4

, M

5

Dams

:

Dam inserts are intended to reduce the full flush volume discharge per flush

cycle. This property was utilyzed for attaining partial flushes to the water

closets for simulating the partial flush cycle of two-step flush devices.

3 .2 Test Sequence

The following test sequence was carried out for each combination of a water

closet

:

a. Testing of the water closets with their original flushing mechanisms

subjected to the full quantity of flush water.

b. Testing of the water closets with their originl flushing mechanisms

subjected to partial quantities of flush water ranging from 40 to 70 percent

of the total flush quantity. This range was based on the rationale that

with a partial quantity lower than 40 percent adequate performanct would

probably not be attained, and with a partial quantity higher than 70 percent,

the amount of saving would not be significant. The partial flush quantities were attained by inserting the dams into the tanks.

c. Testing of the water closets with the two-step flush mechanisms, applying

the full and partial qaantities of flush.
Water Supply Pressure Conditions

Each case of the tests sequence a, b, and c was performed subject to the total

pressure supply of:

15, 25, 40, and 80 psi. (103, 172, 276, 414, 552 kPa)

.

3 .3 Test Equipment and Apparatus

The equipment and apparatus used for conducting the tests are described in

Figure 3. The method for standardizing the flow conditions upstream the water

closet under testing was adopted from the procedure proposed by Stevens

Institute and incorporated in the revised ANSI A112.19.2 Standard. This

procedure is as follows: A standard orifice designed by Davidson Laboratory

is connected to the line in place of the water closet ( "FO" in Figure 3).

Valve V

2 (in Figure 3) is adjusted until a flow of 3-3.5 gpm takes place in

the system at a flowing (static) pressure of 8 psi at no flow conditions.

The orifice is then removed and the water closet sample under testing is

connected to the line. The position of Valve V

2 is remained untouched

throughout the testing.

In addition, the following conditions were imposed in the test at the NBS

Laboratory: The ballcock in the tanks was adjusted to close at the marked

Water Line at static pressure of 30 psi. The drainage system downstream of the

sample included a 90°, 3” sanitary elbow followed by a 3" PVC pipe of 8' long.

This condition was imposed merely for consistency: however, the effects of the

drainage configuration on the performance of the system were not investigated.

3 .4 Laboratory Tests

3.4.1 Geometry of the Water Closet Tanks

The following measurements were made not for testing criteria purposes, but,

for obtaining data on the design of the tanks:

- Establish the relationship between volumetric increments of water from the

marked Water Line in the tank to points below and above the Water Line

together with the following pertinent parameters:

- The volume of water occupied by the tank up to the Water Line

The height of the Water Line in reference to the tank bottom

- The overflow level in the tank in reference to the Water Line

These measurements were made by means of a graduated cylinder and a calibrated

pressure transducer capable of sensing pressure head differentials as low as

0.1 mm. The transducer was inserted in the tank and the water pressure heads were measured (from an initial datum) as increments of 100 ml of water were

added to the tank.

9
T - Water supply pressure tank, 0-120 psi

Pi, ?2 ~ Manometers, 0-120 psi

Vi , V 2 - Flow adjusting valves

PR - Pressure reducing valve h. 0 - Flow totalyzer and flow rate turbine meter

H - Pressure transducer for water level in W.C. indicator

FO - Fixed orifice for test standardization

LP ~ Load platform (flow rate measurement from W.C.)

PPM - Equipment for Water Exchange, pH/Ion concentration and electrodes

WCD - 3" drain from W.C.

Figure 3. Test equipment and apparatus

10
3.4.2

Characteristics of Water Closet Bowl

The following measurements were made primarily for classification of the bowl

types under study and establishing the geometrical characteristics of the bowls

- The relationship between the volume increments of water from the bowl’s

weir level to points going down toward the dip at 2 mm intervals.

- Cross sectional dimensions of the W.C. well at weir level

Trap Seal Height

- Volume of water in the well up to the weir

Maximum flow rate from the bowl during the flush cycle.

The relationship between volume and height increments were obtained in a similar manner as described in 5.3.1. With the bowl empty, water was added by

predetermined increments, and the corresponding increase in water level was measured by the pressure transducer.

3.4.3 Relationship between the Line Static Pressure and the Flow Rate through

the Ball Cock

This test was performed for information on the hydraulic characteristics of the

ball cock. The pressure reducing valve was adjusted for obtaining the desired

static pressure in the system at no flow conditions. Valve V-^ was then opened

and the flow rate and static (flowing) pressure was then recorded.

3.4.4 Water Closet Bowl, Tank and Ball Cock Interaction During a Full Flush

Cycle

The following parameters were evaluated as they effect the performance of the

bowl and the total water consumption of the water closet bowl:

Water usage per flush cycle

- Water wasted over the weir through the refill tube during the flush cycle

Ratio of the maximum refill flow rate to the total maximum flow rate to the

tank. This parameter is important from the water economy standpoint as a large ratio may result in wastage of water over the weir in case when the

bowl is filled before the water level in the tank reached the water line.

This information was obtained from Stevens Institute, from test data on water

closets of the same type and model evaluated at NBS. It is assumed that the

performance of water closets of the same model do not differ appreciably.

11
- Ratio of the refill flow rate and total flow rate at the instant when

the water level in the tank has risen to approximately 1/2" before ball cock

closure. This value is measured to observe the distribution of the flow

between the tank and the bowl when the ball cock resistance is increased.

The water usage per flush cycle was measured by placing a graduated cylinder

under the drain line at the end of the flushing cycle and collecting the excess water flowing over the weir from the time the bowl is filled by the refill tube.

The refill flow rate was measured by diverting the flow from the refill tube to a graduated cylinder for a fixed interval of time for obtaining the flow per

unit time to the refill tube.

All of the following tests were performed for the full and partial flush

quantities of water. Four partial flush quantities were tested which ranged

from AO to 70 percent of the total flush cycle.

3.4.5 Trap Seal Loss and Siphonic Action

The following parameters were evaluated:

- Trap seal loss after the first flush cycle (defined as h

r

) . The trap seal

loss was measured by a pressure transducer which recorded the equivalent

drop in static pressure in the bowl.

- Occurrence of siphonic action in the first and second flush cycle.

"A fully developed siphonic action" was defined in Article 2.1 and was tested by visual observation.

If siphonic action did not take place in the second flush cycle, the

parameter V

c defined as the minimum quantity of water required for adding

to the bowl for attaining siphonic action, was evaluated.

If siphonic action takes place for two consecutive flush cycles the test

continued with two additional flush cycles for testing whether siphonic

action takes place for four consecutive flush cycles.

Test Procedure

The tests were performed for the full and partial flush cycles for five nominal

line pressures of 15, 25, 40, 60 and 80 psi (103, 172, 276, 414, 552 kPa)

.

Step 1. With the tank filled and the water in the bowl full to the weir a flush

cycle was initiated and the following data recorded:

- Maximum ball cock flow rate in the flush cycle. Measured by the turbine

flow meter.

- Ball cock static pressure at maximum flow rate.

r 12
Total flow in the flush cycle. Measured by the turbine flow totalyzer

(turbine meter)

- Adequate siphonic action (denoted by yes or no)

- Trap seal depletion in height

- Trap seal depletion in volume obtained from the data of the geometry of the

bowl.

If siphonic action occurred in the first flush cycle, the testing proceded to

step 2; otherwise no further testing was made.

Step 2. Step 1 was repeated retaining the water in the well from the previous

flush. If siphonic action took place, Step 3 was performed. If siphonic

action did not take place, the following steps were carried out.

The bowl was filled and the handle tripped for a partial flush cycle. One

hundred ml of water were added to the well and tested for siphonic action. If

siphonic action did not take place, the bowl was refilled, flushed again and

200 ml added. This sequence was repeated with another increment of 100 ml until

siphonic action took place. The water volume required to replenish the depleted

well to create a siphonic action in the next flush cycle was defined as "critical

volume" and denoted by Vcr.

Step 3. With the water in the well in the state which occurred in the second

flush cycle, two more flushes were made to determine whether siphonic

action takes place for four successive flushes.

The Granule Test

The granule test as specified in the revised ANSI A112.19.2 Standard (Article

7. 4. 3. 2) is intended for testing the performance of the bowl in its removal of

slurry material. The test medium is 100 ml of disc-shaped polyethylene granules

2-3 mm in diameter and a thickness of 1 .5 mm. The granules are inserted into

the bowl, and the water closet is flushed. The criterion for passing the test

is that "not more than 125 (5%) shall be visible in the well after each initial

flush .

The interest in applying this test for the partial flush cycle was primarily

for seeing whether the granule test may serve as a means for quantifying the

test of siphonic action. The test was therefore applied for the full and

partial flush cycles.

3.4.6 Water Exchange Test

The water exchange was evaluated by the value of the "relative concentration

ratio" defined as a ratio of the concentration of liquid contaminants in the

bowl after usage of the water closet and the residues after flushing. For

partial flush cycles this test was performed twice. In the first time, the bowl was tested with its well full to the weir with fresh water. In the second time,

13
the bowl was tested as left from the first time, namely, with residues in the

well and no water was added to replenish the trap seal. The relative concentration ratio was calculated as follows:

Cql C

b . Cq2 Cb

Ri = „

’ R9 =

C il C

b

C

i2 " C

b

where

:

is the background concentration of contaminants in the bowl

C.q is the initial concentration of simulated contaminants before

flushing the water closet

C

i Concentration of the residues of the simulated contaminants after

the flush cycle

Ci2 is the intitial liquid waste concentration resulting from liquid

wastes which remained from the previous flush cycle and a new

load of simulated contaminants

is the final concentration after the second flush cycle

In the initial tests, the medium was sodium chloride from which a solution of

4 percent (by weight) was prepared and the test load constituted 200 ml of that

solution which was inserted in the bowl prior to flushing. There was no intent

to simulate the actual sodium chloride concentration which normally occurs in

liquid wastes. This relatively high concentration of the test medium was

used to reduce errors in the measurements of small concentration which may occur after the flushing cycle. In the course of fthe initial testing, it was found

that the background concentration of chlorides is in the range of 15-30 parts

per million (ppm) and the errors in measuring these values is in the range of

the values which occur in the tests. The test medium was therefore switched

to sodium bromide (NaBr). Sodium bromide is completely soluble in the range of

the concentration used and its concentration in the water supply is less than

0.05 ppm. Thus, higher accuracy was attained, in addition, the frequency for

checking the background concentration was appreciably reduced.

The urine from an adult for a 24-hour period is 1,500 ml at a total common

salt content of 15 grams. This probably amounts to an average single load

of 200 ml at 2 percent NaCl concentration [15].

2 Table 17 in Appendix B indicates the level of residues (C^) as obtained wi :h

four levels of loads (C^). As observed the values of "R" are nearly identical

for all test loads. These results show that this test method is reproducible,

furthermore, "R" is independent of the initial value • However, as C is

reduced (to 5 ppm) the relative errors are increased, and the larger the

value, the smaller the errors in C . q

14
Test Procedures

a. Equipment

Numerous instruments are available for measuring ion concentrations in salt

solutions. The laboratory equipment used in these experiments was: (These

items listed below could be replaced by many typically similar devices)

.

- Fisher Model 750 pH meter

- Bromide ion electrode (No. 9417) manufactured by Orion

- Reference electrode (No. 9970) manufactured by Orion

Sodium bromide salt in crystal form

- Standard (1 mole) bromide solution

The Fisher Model 750 instrument enables measuring concentrations (in ppm)

directly by its built-in microprocessor. Prior to testing, two samples of

known concentrations are read in the instrument and the calibration curve is

internally generated for direct reading of the sodium bromide concentration

in ppm units.

b. Measurement of Sample Concentrations and the Evaluation of "R"

.

Step 1. Measures background concentration of sodium bromide. This value

was assumed as constant throughout the day's work.

Test medium: 200 ml of 4 percent by weight of bromides (51.5 grams of sodium

bromide per 1000 ml of water)

.

Step 2. With water in the bowl full to the weir, the test medium was inserted

and thoroughly mixed (with a stirring rod) . Two samples were taken

from the bowl and their concentration measured. The mean concentration

of the samples represented the value C.q.

Step 3. The toilet was flushed, the water in the bowl thoroughly mixed again

and two samples were taken from the bowl. Their mean concentration

was represented by the value Cqi Also measured were the total flow

in the flush cycle and the volume of water in the well.

Step 4.

Step 5.

The value of R^ = (C

^ “ ^b^^il "* ^b^ was t ^ien computed.

When partial flush quantities were tested, steps 2 and 3 are repeated

except that the toilet is flushed with the water level in the well

remaining unchanged from step 3. The occurrence of siphonic action was recorded. The value R

2 = ^ C

q2 ” Cb^C

i2 ~ ^b^ was comPute ^*

15
3.4.7 Test of Paper Removal

A "normal test load" of toilet paper was assumed to be in the range of six to

twelve double strips approximately 4 1/2 x 4 1/2" of commercially manufactured

toilet paper. The test was conducted with six double strips (six pairs) cut

from the toilet paper roll and then repeated with twelve double strips after

complete bowl refill.

The following procedure was carried out for the partial flush quantities of

water:

With the well full to its weir, the test load was inserted in the bowl, allowed

to soak and the flushing handle tripped for a partial flush cycle. The number

of strips of paper which remained in the bowl were counted. The observation

of the occurrence of siphonic action was also recorded.

If at least one strip of paper remained in the bowl, the test was discontinued.

If all the toilet paper was removed, another test load was placed in the bowl,

without replenishing the trap seal and the test was repeated.

3.4.8 The Rim Wash Test

The purpose of the Rim Wash Test is to test whether the fresh water from

the toilet tank reaches all the possibly fouled exposed areas in the bowl.

Therefore, a test medium is required whose properties are such that it is

washed away when water reaches it, and provides a basis for measurement by:

Elimination of subjective judgment

Repeatability of results

Simplicity of preparation of the medium

Possibility for quantification and rating of the results

Several test evaluation methods which were considered and tried:

1. The Saw-Dust Test

The "saw dust test" is used in foreign standards [8] for testing the capability

of the water closet bowl in washing all the exposed areas of the bowl. The test

entails spreading saw dust particles on the surface of the bowl and observing

the bowl after the termination of the flush cycle. It is generally required

that no traces of saw dust will remain on the surfaces. The preparation of

this test medium and the testing procedure are simple. However, the outcome

of this test cannot readily be reduced to a quantified measurement since the

residues of the saw dust, i.e., density distribution of areas, or weight of

particles remaining on the bowl cannot be readily determined. Furthermore, it

is difficult to establish a pass/fail criterion for evaluating regions with

small amounts of remaining residues, unless the requirement for passing is a total removal of saw dust particles.

16
2. Chemical Methods

The pH of the water in the tank was raised to relatively large values [8, 9, 10]

by inserting sodium hydroxide pellets in the toilet tank. PH indicators were distributed in the bowl for the detection of the basidity of the incoming rim

wash so that the areas which were washed by the incoming water changed color

and the areas where water was not reached remained unchenged.

The detection of the basic water was made by the following two methods:

a. Pasting pH strip indicators around the circumference of the bowl spaced at

various intervals.

b. Coating the bowl with a solution containing phenollihelene (by brushing)

such that the areas on which water from the tank reached turned pink and

the other areas remained white.

Method "a" yielded distinct and reproducible results; it was, however, discounted

because it required a relatively long time for preparation. Method "b" was easy

to prepare; however, it did not yield results which could be easily interpreted

without resorting to subjective judgment, i.e., the areas reached by the basic

water from the toilet tank could not always be easily identified from the areas where water from the tank did not reach the bowl.

3. Marking of Dots and Lines - Paint Test

Marking the bowl surface with artists water color paints applied as test media

in dots or line patterns. The research teams of Stevens Institute of Technology

in their search for test methods for the rim wash tests conceived this method.

Experiments with two methods were evaluated (a) Marking four horizontal lines

of approximately 1/8" in width around the inner circumference of the bowl.

These lines were spaced 1/2 to 3/4 inch apart starting 3/4 inch from the rim

and going down with the fourth line 1/2 inch above the water in the well.

(b) Dots of approximately 1/4 inch in diameter were marked in the bowl, spaced

1/2 inch horizontally and vertically.

Dots as test media have an advantage over lines as unwashed areas are indicated

by counting discrete points as compared to the measuring lengths of unwashed

line segments. A uniform method for drawing the dots on the water closets was provided by preparing paper stensils with a fixed arrangement holes so that the

dots could be placed in a consistent manner on the bowl. The stencils were

taped to the bowl and painted; upon removal, the dots remained on the water

closet surface area. The flushing mechanism was then actuated and the water

flowing from the tank washed away the markings. The total length of unwashed

lines was then measured for Method (a) and the total number of unwashed dots was counted for Method (b).

17
In successive tests of identical input conditions, marking four lines and

painting dots proved to the reasonably reproducible. Preparation of the test

medium however proved to be rather cumbersome and time-consuming. It was,

therefore, decided to test the water closet samples in accordance with the

procedures outlined in the revised ANSI A112.19.2 Standard as follows:

Test Medium . A fine tipped, felt pen containing a dark colored, water soluble

ink.

Procedure. The flushing surface is scrubbed clean with commercial scouring

powder to remove any buildup or deposits on the walls. The surface is then

rinsed and dried with oil-free air.

An ink line is drawn around the circumference of the flushing surface at a level one inch below the rim jets of the bowl.

The flush release device shall be tripped and the line observed during and

after the flush.

When the flushing cycle is completed (tank completely refilled or flushometer

cycle completed and trap refill water delivery completed), the lengths of the

unwashed line segments where the ink may have remained on the flushing surface

is measured and also recorded are approximate positions in the bowl.

This test was performed four times for each test case (partial flush quantity

and water supply line pressure)

.

3.4.9 Additional Tests of the Two-Step Flush Devices

3. 4. 9.1 Mechanical Evaluation

The following mechanical evaluation was made by visual inspection and manual

manipulation of the. devices:

Ease of installation of the device into the tank

Compatibility of the device with existing mechanisms and parts in the water

closet tank

3. 4. 9. 2 Watertightness of Flush Valve

Each device was installed in the tank of all the water closet samples. The

tank was filled from the water supply line assembly. The flush valve was tested

for leakage during the tank fill cycle and after termination of fill.

3. 4. 9.

3

Consistency in Delivering Fixed Partial and Full Quantities of Water

Each device was tested by measuring the quantity of water delivered for the

full and partial flush cycle, for five consecutive flushes.

18
4. DISCUSSION OF THE LABORATORY TEST RESULTS

The development of criteria and testing procedures are based upon a set of

principles which must be considered:

The basic operational functions and performance requirements which the

product must meet.

- The present state of the available manufactured products and their capabilities

in terms of meeting these requirements.

- Formulation of the simplest possible test specifications whose test outcome

reflect the performance of the product. The purpose of the tests conducted

was: (a) to provide a basis for establishing the performance requirements

for two-step flush devices, (b) determine the practicability of the various

tests and measurements, (c) assess their feasibility to determine performance

levels

.

The water closet samples chosen for these tests are the most commonly used in

the country so that the conclusions drawn from the test data are reasonably

general.

4 .1 Characteristics of Water Closets

The laboratory tests were limited to six water closets from four manufacturers.

These samples showed the variability in the characteristics of water closets.

Table 1 and Figures 4 and 5 illustrated these findings, from which the following

variations among the systems may be observed:

- Trap seal height

- Volume of trap

- Dimensions of the bowl water surface

- Hydraulic characteristics of the ball cock

The flow rate from the bowl

The geometry of the trapway, which is an important parameter, could not be

evaluated as this requires cutting the bowl to measure its internal dimensions.

The samples contain two water closet groups. A^ , CR^ , and are water conser- vation models and B 'A^, and CR^ are conventional 5-gallon water closets. The

pairs (A

2

, Ac) and (CR^, CR^) have identical bowls. In the case of the first

pair, the only modification was made in the flapper valve control for delivering

a smaller quantity of water per flush. In the second pair, the water saving

model has a tank of a smaller volume.

19
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20

Table 1.

Characteristics

of

Water

Closet

Bowls
20 1pm 15 1pm 10 1pm 5 1pm

Flow Rate - gpm

co -aco

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CD cn

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21

Figure

4.

Ball

cock

flow

rate

to

the

tank

in

time

for

three

w.c.

samples

for

two

pressure

conditions
Flow

Rate

-

gpm

Figure 5. Water flow rate for various water closet bowls

9> *Samples X and Y were noi included in the program - these data were

supplied by Stevens Institute of Technology.

22
4.2 Tests of Siphonic Action and Trap Seal Retention

The tests showed that "a fully developed siphonic action" as defined in Article

4.1 is an important criterion for the evaluation of the performance of the

water closet bowl. A siphonic action is essential for an adequate water

exchange and the removal of paper wastes (as discussed in Sections 4.3 and 4.4).

Considering the use of a two-step flush mechanism, the following situations may

occur:

a. No siphonic action takes place for the full flush cycle even if the water

in the well prior to flushing is filled to the weir.

b. Siphonic action occurs when the full quantity is flushed, when the water in

the well is full to the weir, but no siphonic action occurs when the trap

seal volume is reduced from the previous flush cycle.

c. Siphonic action at all times for the full-flush cycles, even with depleted

well, but no siphonic action with partial flush cycles.

d. Siphonic action for the partial flush quantity only when the water in the

well is full to the weir.

e. When partial quantities are flushed consecutively, a reduction of the water

in the well increases from flush cycle to flush cycle and eventually

siphonic action does not take place.

Tables 2a through 2f and Table 3 illustrate these cases in the water closets

tested. Among the parameters described in Tables 2a through 2f, V

Cj. is of

significant importance. Since it shows when siphonic action did not occur and

indicates the volume of water required to add to the depleted trap in the bowl

to affect a siphonic action. Table 3 describes the behavior of the bowl for

successive partial flush cycles. As the water in the well is gradually reduced

at some point, siphonic action no longer appears to take place. This is due to

the fact that some quantity of water which was designed to contribute to the

siphonic action is used instead for filling the bowl and priming the siphon.

23
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24

VrVolume

of

water

required

to

refill

well

after

the

flush

cycle

hrTrap

seal

height

reduction

after

the

flush

cycle

VcrVolume

of

water

required

to

replenish

the

depleted

trap

for

obraining

syphonic

action. *

indicates

that

syphonic

action

took

place

in

the

second

partial

flush

cycle

and

there

was

no

need

to

add

water

to

the

well.
Table

2b.

Test

for

syphonic

action

and

trap

seal

retention cox

D->4

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25

indicates

that

syphonic

action

took

place

in

the

second

partial

flush

cycle

and

there

was

need

to

add

water

to

the

well.
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15.0 15.6 17.6 19.2 21.2

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WL2~

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pressure

(t

num

flow

rat

water

passec

wasted

over

water

passec

BaX

2.0 LA• CM

3.1 3.9 4.7

KPa |

103 172 276 rH 552

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c/s P- 15 25 40 09 08

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26

VrVolume

of

water

required

to

refill

well

after

the

flush

cycle

hrTrap

seal

height

reduction

after

the

flush

cycle

VcrVolume

of

water

required

to

replenish

the

depleted

trap

for

obraining

syphonic

action. *

indicates

that

syphonic

action

took

place

in

the

second

partial

flush

cycle

and

there

was

no

need

to

add

water

to

the

well.
Table

2d.

Test

for

syphonic

action

and

trap

seal

retention

m

Pi

CJ

CD rHaS

(0 CO

M 4.

J : O T > r-44 M § £ 1

CN

4.

J 5 M T > 1-44

4-

J

CL,

T4 > f4 u *.J O T*» >• «-4

J= rH£ 4.

J

U

T4 > r-44J Cl *r4 > r-4

Pi o O

•H •H

U 4 J 4J 4-1 O T-i O CJ > --I CO CO o o

*r4 •H

U 1 3 3 3 cn o 3 O O rH rH X 4=

U- "P- c >s

m o o

tJ 4-•

X CO Os i-'-

m 3 H •»-4 • • • > f-1 o o o o o 2 2 O Os 00 m cn « J • • • • Cl th m CN m > r4 rH rH C U o o u *r4 > 1H 4J o o o o r-1 o

(0

cj L4 =i *r4 .c a C OS

m o o O

O'

a

cf in o 3 Vl *H CO m cn > r-4 • • 1 i O o o 2 U 00 o cn m o

O.

H • • • • • > h i-"- Os o rH

rH rH o o O o ~a~ *J 1^ 00 sO o 3 H • • • • • > -• o o o rH rH

CN so sO r- sO

4-J • • • • • MH •H CN CN CN cn <r > —• rH rH rH rH rH X

rH <r o o Os

B • • • • co Cl Os CN m SO J J rH rH rH

co co CN sO Nf CN O !" rH m ^ rH rH CN <r m

r-3 ITS in o o o

cn i—4 CN SO 00 co

cjCOo

•HcoXa

sn

coocc

•HC

couX

4= o

CO <d 3 r-4 V4 r—4

CJ o

14-1 >s *4-1 O

*4-1

a

O 4= co

CO i* CO 3 4J

0) rH •H *4-1 •o

4-1 CD •H V 4-4 4-1 0) x (D CD 3 rH 4J r—1 rH

CO CJ CJ 0l 3 Jn H >s CD O' CJ 0) cj *0

CD 4-1 i-4 x I—1

l|-4

X CD CO CO CJ CO CO X

•H 0) 3 3 4-4 4-1 i—4 i-H O i—4

r-4

U CJ *4-4 i—4 <4-1X

cO fn

x CD CO a. o r-4 CO 3 <D t4

i-4 3 X 3 u 4= 3 r-4 ^4 4-4 0J o CO CM 114 rH r-4

*4-4 3 •H

u c- rH CO i—4 14-1 0) CD CO IL4 CO a; 4-1 O 3 c t4 M *4-1 o !-4 •H 4J CO o

•H 44 i-H

U o 4-1 4-1 C 3 U CO 4-1 c

CO CO 14-1 •H a.

O T3

U 4-1 0) •O •H CD 3 s CO 3 CO CD 4-1 i-t 00 i-4 0 O CJ *H •H CO 4J C <d c •H 3 3

IL4 4-1 •H 4= •H 3 TJ O’ c O <D 4-1 O' ID CD O 4J 4J *0 T3 CD Lj H o —' (fl 11 U ID )-i lJ CO CD CO 4-1 L- 1 CD CO > CO u X 0) M 3 «0 O CO (D bO 4-1 CN 3 0 0. a. 4—1 *H CO g

CO rH •o CO CD 3

CO *4-4 V4 CD Lj 3 X

a) a> 4-1 (D SM * M E 4-4 CO 4-1 14-1 rH o

rH

a 3 co co CO o CO tJ c 3 3 3 a) CD C0 *r4 <D CO B

t4

x rH

u rH 6 3 - 4-1 CO CO 0) CO 3 O* rH o CO 2 4J 4J 4-1 ,

l CO O

rJ 4J

O CO o O > 3 cn i h 3 H > H |

r, 1 X 1 1 1 1 1 m CO

u

g

H 6*4-1 3 a V4

u CJ O, O' > > > > X > oc L

27

indicates

that

syphonic

action

took

place

in

the

second

partial

flush

cycle

and

there

was

need

to

add

water

to

the

well.
Cl

CO

-Oc

COco

•H

4Jo

cOoHco4=CL

CO

Clo

CM

CO

0) H• 0) CM

cu rH43

cO H

M xj o o o o>

•H

rH vO vO o O o O o M

4= E 00 vD cO 1 '

<N

m

O o o 4J CM 00 in CM 3 M •H • 1 > rH d o d o

XJ CM o cr> o>

O CL •H • • • • > rH 00 CT\ 00 O' rH

rH

M XJ o>

*Ti rH o O o o o g vO v£> rH 1 i 4=

s—{ IJ3 XJ vO vO M •H • 1 g > rH o o d

00m CTv XJ • • e • a *H c* (T> O rH CM > rH rH rH rH M XJ O •H o o o o o > ^H M e 1 | | g 43 e C

[J

M •H 1 1 | | j > rH

CO CM

m 00 « • • # CL *H t-H CM CO m > rH rH rH rH tH rH M

CJ XJ > •H o o o o o

rH

M

B

4=

B 1 I i i i

co

XJ 5 M> rH i 1 i i i

XJ CO vO in r- O'

CL •H e • • • • > rH CN CM co <r m rH rH rH rH rH

4J o m o m

m

<r r-» 3 •H • • > rH o o o o o o CO m XJ • • • • • 4-1 •H <r in m m vO > rH rH rH rH rH rH X B

vO

m• o vO cO

03

a CD 00 rH CO

m i-3 rH rH rH

03 CO CM v£> CM

P-4 o i—1 m

r-H rH CM •vf in

phJ

mmO o O C/3 rH CM <3* v£> 00

Pl

4=

CO <u 3

i—l o

IM So

CJ IMo 4=

CO CO 3

0) pH •H IM

4-1 •H a)

4-1 4> 43 3 l—l M

CO o 3 >1

M

er CJ CU 41 M

r-l 4= pH IM

co COa CO •H a> 3

4-1 fH |M CJ iH M <J IM rH

CO SO x. (1) CL O i—1

CO 3

rH 3 M 4= 3 pH rH O CO CM CM rH

CM 3 •H »M cfl rH CM

CO IM CO <u C C *H Ci o rH -H 4J •H 44 i—l MO M C 3 M CO M

CO (0 cm rH Cl M 4-> 41 T3 3 /"*> !0 3 ffl 0) bOM O Cl •H CO M C 4) C *H «M 4J *H JC *M 3 C O 0> M cr o 4-1 m -a -o 41 u s-x CO 4) M 4) M M CO 4) CO i 5J CO > CO M M 3 (0 O CO 41 CM 3 o o. a M

(J CO rH -a CO

CO <MM 41

M 3

cu 41

M 4)

M

B 4-> CO

M CM

rH CL 3 co CO CO o

(J

C 3 3 3

CO •H 4) •H X -H M iH B M CO CO 4) cO 3 o CO S M M 4-1 i—i

•J

M o CO o O

12 CO 1 H 2 E-l > - 1 X 1 1 1 | co co H E cm 3 a M 5 CM O' > > > >

28

hrTrap

seal

height

reduction

after

the

flush

cycle

VcrVolume

of

water

required

to

replenish

the

depleted

trap

for

obraining

syphonic

action. *

indicates

that

syphonic

action

took

place

in

the

second

partial

flush

cycle

and

there

was

no

need

to

add

water

to

the

well.
Test

2f.

Test

for

syphonic

action

and

trap

seal

retention PO> u

rH P p P

:tion. 1

there

was P

42 mm

B

•H

4JO

CO tT

4-

C.CC 0

•H

4-1 O

CO 0

•H

4J0

c0

—&

•H

4-1 O

c0 CM g Vr O

•HCO

c. •rCc

rf

O

•HPO

42

O

•HPO

42

O

•HPO

42 >

JAt.

IS>

CO0

is P0C2

Ph

to

COO2

C-L SO

CO0Z

u.

C00z

Vcr

4-i •HrH

uc or UC P0 p0 p

42

unu I

•H

4-1 O

CO

1-4-

c.CO

acti

•H

4-> O

CO

•H

AJ

CJ

cti

H£

Vr

u

UtJ

cJ •Hc0

42CL

c.c0

42Q

phonic 0

•HPO

42

CL

u

•HPO

42

CL 1

quantities

of

flush

h

cycle

le

fter

the

flush

cycle

h

cycle e

depleted

trap

for

obraining

syphonic

ac

ace

in

the

second

partial

flush

cycle

anc

a>

AJ •HrH No

sy £

CO0

2; No

sy

Po

COOZ

COOZ

Vcr |

lit c c c c e P

4= i

•H

4J

CJCO

•H

4-1 O

CO

•H

4-1 O

CO

•H

4-1 O

CO

•H

4-1 O

CO cg Vr |i

lit J

O

•HCO

4=Cl 0

•HPO

42

Cl

a

juoljc

U

•HPO

42

CL.

U

•HPO

42

CL

a>

Llit I

No

sy

No

sy

No

sy

No

sy

PO

CO0Z p0> lit I

action action 1.20 0• 0

0.20

co

!*

is

for

partia

flush

cycle

a

full

flus

al

flush

eye

efill

well a

ter

the

flus

replenish

th

tion

took

pi

well. P

42 j

aim 0

•HOc 0•HPO

23 19 13

Vr |

AJ •HrH

—42-

o.

to

CO0

P'.

42a

to

CO0

1.50 1.30 1.00

a> 1 1 6

'9

7.9 CO

CO

ration tank

full

eir

in

parti

d

tor

ion

af

ed

to

nic

ac 0

the

*A

1A

XKU1 0

AJ •HrH j 0.15 0.45 0.55 0.77 1.20 3 ^ igjigmuLOU bOr-4 0 P <J -H 42 •Hc04_>COPi-I 32!CLP

M-I4J H42-Hp'Ocr>.a) coo 4-1 crooco4-i

Sample :K3 1

lit I

11.4 12.1 CMCM

tH

13.9 14.8

fLi,

WL2-

Cc ;

pressure

(t

num

flow

rat

water

passec

wasted

over

water

passec ;

of

water

re

leal

height r

le

of

water 1

licates

that

:ed

to

add

we Ea

-J

6.4

r-M 00 11.4 14.3 16.2

P- !

KPa 103 172 276 <r

rH 552

WLo,

Statis -

Maxi

Total Water Total

Volume

Trap s

Volun *

inc

no

ne

PSL in

rH CvJ 40 09 80 1 •>1X11111 co nj P

-J

H E<4-i 3 a P P 0 50lO'>>>>42>

29

indicates

that

syphonic

action

took

place

in

the

second

partial

flush

cycle

and

there

was

need

to

add

water

to

the

well.
Table 3. Occurrence of siphonic action for successive applications of partial

flush cycle

For successive flush cycles:

y - indicates that siphonic

n - indicates that siphonic

action occurred.

action did not take place.

W.C. Sample:

Case : WL3

Volume

Cycle flow 1st 2nd 3rd 4th

A 10.2 y y n 10.4 y y y n

11 .2 y y y y

12.2 y y y y

13.3 y y y y

Case: WLO

Volume

Cycle flow

a 1st 2nd 3rd 4th

8.9 y n 9.5 y n 10.0 y y n 11.0 y y y n

12.1 y y y y

Case: WL1

Volume

Cycle flow 1st 2nd 3rd 4th

a 7.8 y n 8.2 y n

8.7 y n 9.6 y n

Case: WL2

Volume

Cycle flow 1st 2nd 3rd 4th

Si 6.5 y n

6.9 y n 7.5 y n 8.4 y n 9.4

30
Table 4 Illustrates cases for which siphonic action did not take place and

provides the values of V

p

, Vcr , and V + V cr

» V

p

is the total water usage

for the partial flush cycle and V

cr the add water to the bowl required for

siphonic action. V

p

+ V r signify the total water required to attain siphonic

action.

Table 4. Values of V

p

and Vcr for Two W.C. Samples

V

P

V

c V & V

p cr vp

V

c v„ & v„ r p cr

8.9 0.4 9.5 9.4 0.4 9.8

9.5 0.9 10.4 8.2 0.7 8.9

7.8 1.1 8.8 9.0 0.6 9.6

8.2 1.2 9.4 8.9 0.6 9.5

8.7 0.9 9.6

9.6 0.4 10.0

6.5 1.9 8.4

6.9 2.0 8.9

7.5 1.8 9.3

8.4 1.2 9.6

9.4 0.3 9.7

As noted from Table 5, the values for V + Vcr are nearly constant in the

range of 8.9-10.5 liters (2. 4-2 .7 gallons). The practical aspect of the value

for V is that it indicates the change of the refill required in order that

siphonic action will take place for the particular partial flush cycle.

Returning to the five possible cases ("a" through "e" ) which may occur in a partial and a full flush cycle, the following conclusions may be drawn:

Cases "a" and "b" should be considered a failure as the device interfers with

the normal operation of the toilet for the full quantity of flush water.

Case "c" is not desirable as no siphonic action takes place in the partial

flush cycle.

Cases "d" and "e" are marginal, as siphonic action does not take place all the

times for the partial quantity of flush. As discussed in Articles 6.3 and 6.4,

the performance of the bowl is strongly dependent upon an adequate siphonic

action. With the assumption that a full flush cycle will eventually be used,

a failure for obtaining a siphonic action after several consecutive partial

flush cycles may be tolerable.

Therefore, a reasonable requirement may be formulated as follows:

Siphonic action is required for the full flush quantity of water at all

times.

31
Siphonic action is required for the partial flush quantity, at least, for

three consecutive flushes. o

As observed from the limited data, these requirements imply that the water usage

per partial flush cycle is at least 10 liters as indicated by the tests performed.

Trap Seal Retention

Partial-f lush cycles nearly always cause a depletion of the trap seal levels

since the refill time is reduced and a smaller water quantity is delivered to

the bowl. Tables 2a - 2f illustrate the depletion of the trap seals in the

water closet samples when tested for the partial flush cycles. This depletion

of the trap may be prevented with the ball cock refill flow rate is increased;

however, any increase of the refill flow rate will cause an excessive weir

overflow for the full flush cycles. However, taking into considerations

performance requirements for household drainage systems as cited in codes

[13], the following requirements may be formulated:

"The reduction in the water closet trap seal height after any flush cycle shall

not exceed 25 mm (1 in).”

The Granule Test

The "Granule Test" as specified in the revised ANSI A112.19.2 Standard was applied to evaluate the removal of slurries. The intent of this test was not

to simulate any aspect of the functional performance of the water closet bowl

under partial flush conditions, but to observe whether this test may serve as means for quantifying the siphonic action in the water closet bowl. Table 5

summarizes the test results for one sample tested. As would be expected, when

no siphonic action takes place, most granules are not flushed and remain in the

bowl. When siphonic action takes place, at least 90 percent of the granules

are flushed down the toilets. This test would not be recommended for testing

two-step flush devices, since the test for siphonic action provides a more

reliable information on the hydraulic performance of the water closet.

4 .3 Water Exchange Test

Water exchange test was included in the revised ANSI A112.19.2 Standard. The

test medium is a standard dye solution from which several comparator samples of

varied concentrations are prepared. The dye solution is inserted into the W.C.

bowl and flushed. The dye concentration of the residue in the bowl is determined by visual comparison against the comparator samples. The revised ANSI

Standard specifies that "a dilution ratio of at least 100 shall be obtained in

each initial flush." This comparative test for evaluating the residue of the

contaminants in the bowl after flushing is relatively simple and inexpensive.

In anticipation of future needs for a more accurate evaluation for the water

exchange process in the bowl, particularly as low flow water closets may be

acceptable, other test methods were sought.

32
Table 5. Granule test results for partial flush cycle

The granule test was performed as specified in the revised ANSI 112.19.2M

Standard:

100 ml of polyethelene granules 2-3 mm in diameter are placed in the bowl's

well and the toilet tank flushed. The number of granules remaining in the

bowl are counted or weighed.

Case: WL3

Case: WLO

Case: WL1

Case: WL2

Volume

Cycle Flow

£

1st Flush Cycle 123 Mean

2nd Flush Cycle 123 Mean

Siphonic

Action

10.2 51 40 44 45 33 42 60 45 yes

10.4 29 22 35 27 13 7 33 18 yes

11 .2 12 9 11 10 9 12 12 10 yes

12.2 9 6 7 8 8 11 6 8 yes

13.3 10 13 7 10 11 9 10 9 yes

Volume

Cycle Flow

£

1st Flush Cycle 123 Mean2nd Flush Cycle 12 3 MeanSiphonic

Action

8.9 65 81 95 80 All 90 ml 90 ml 93 ml no 9.5 35 35 36 35 74 150 125 117 yes

10.0 22 16 19 19 18 12 21 17 yes

11.0 20 22 12 18 12 17 23 17 yes

12.1 13 13 14 13 9 16 20 15 yes

Volume

Cycle Flow

£

1st Flush Cycle 123 Mean2nd Flush Cycle 12 3 MeanSiphonic

Action

7.8 46 75 60 60 All All All All no 8.2 30 44 40 38 All All All All no 8.7 34 32 28 31 90 ml 90 ml 90 ml 90 ml no 9.6 24 22 20 22 110 120 160 130 yes

10.7 17 21 23 20 40 26 18 28 yes

Volume

Cycle Flow

£

1 2 3 Mean 1 2 3 Mean

Siphonic

Action

6.5 87 90 99 93 All All All All no 6.9 55 81 71 69 All All All All no 7.5 41 32 41 38 All All All All no 8.4 20 23 26 23 All All All All no 9.4 27 28 17 24 All All All All no

33
As described in Section 5. A. 6, the parameter used for the evaluation of the

water exchange was the "relative concentration ratio" defined as the residues

of the contaminants after flushing the bowl divided by the level of contaminants

before flushing, where it has been assumed that a substance can be placed in

the water closet for simulation purposes. For a test medium, any water soluble

substance can be used as long as an instrument is available for measuring to a reasonable accuracy a range of concentrations of 1/10 to 1/10000. Several

test media have been used in the past by various researchers. Brunei University

[1A] used sodium permanganate as medium to evaluate the water exchange of European

water closet bowls. The parameter measured was the "optical density" from which

the dye concentrations are derived. The Standards Institute of Israel [15, 16]

used sodium chloride for a test medium. The concentrations were evaluated by

titration with a solution of silver nitrate (AgNOg) and the use of potassium

chromate (KCrO^) as an indicator.

In addition to the test procedure specified in the revised ANSI A112.19.2 which

was proposed by Stevens Institute, the dye dilutions were evaluated at Stevens

Institute by a fluormeter which measures the relative light intensities and

converted by a calibration function to concentrations. As described in Article

3.2.3, the test medium used at the National Bureau of Standards’ laboratory

was sodium bromide. Eventually, all these methods should be compared and

evaluated in terms of their simplicity, required time of preparation, testing

time, and accuracy.

Test Results

Tables 6a through 6f and Figure 6 describe the relationship between the relative

concentration ratios and the total flow in the flush cycle for the water exchange

test on one of the W.C. samples. A sharp increase of "R" takes place with the

reduction of the total inflow to the W.C. bowl. R

2 represents the values for

the corresponding partial quantities flushed the second time. As observed,

siphonic action strongly affects the level of residues remaining after flushing

the bowl. In the absence of an adequate siphonic action, an appreciable portion

of the liquid contaminants may not be flushed from the bowl. Siphonic action

was attained for partial flush cycles of 10 liters and the values of "R" did

not exceed 0.05. In accordance with the requirement of the ANSI A112 Standard

values over 0.01 would not pass the test. Table 7 indicates the results of

water exchange test conducted with European wash down water closets. The values

of the relative concentration are in most cases appreciably smaller. In addition,

a good water exchange can be attained with volumes as low as A liters. The

reason may be attributed to the fact that evacuation of the water from the

european bowls is by weir action and a large portion of the water in the well

flow out by an apparent piston action. In addition, the volume of water in the

well for European water closets is only half as much as the volume for siphonic

water closets.

See Appendix A for test accuracy analysis.

3A
Table 6a. Concentration ratios of sodium bromide in the w.c. well,

before and after flushing

Test medium: 200 ml. of 4% sodium bromide (NaBr)

- Concentration ratio in the first flush

R2 - Concentration ratio in the second flush

V - Watet inflow to the W.C.

W - Water in the W.C. well in the second flush

P - Statis pressure in psi

Syphonic Action - Denotes whether syphonic action

took place in the second flush cycle

R1 " < cil * Cb )/Cql - Cb ) R2 ~ (Cf2 - Cb )/Cq2 — Cb ) Where:

M C" denotes NaBr concentrations

in ppm as follows:

Cb - Background concentrations

Cii - Before first flush

Cqi - After first flush

ci2 “ Before second flush

cq2 - After second flush

Sample:

Water Exchange Test

Flush

V inflow W W • C. R

1 R

2 Syphonic

P gal. lit. gal lit. Action

Partial 15 1.87 7.08 0.774 2.93 0.102 0.497 no Quant. 25 1.97 7.49 0.708 2.68 0.090 0.438 no

1 AO 2.12 8.02 0.692 2.62 0.070 0.377 no

(vl2 ) 60 2.35 8.89 0.708 2.68 0.047 0.284 no

80 2.62 9.91 0.626 2.37 0.038 0.056 ves Partial 15 2.13 8.06 0.869 3.29 0.065 0.422 no Quant

.

25 2.19 8.29 0.829 3.14 0.065 0.384 no

2 AO 2.3A 8.86 0.808 3.06 0.052 0.298 no

(WLX ) 60 2.55 9.65 0.824 3.12 0.039 0.064 ves

80 2.87 10.86 0.875 3.31 0.026 0.035 .yes.

Partial 15 2.49 9.42 0.967 3.66 0.024 0.071 no Quant

.

25 2.58 9.77 0.888 3.36 0.033 0.049 ves

3 A0 2.75 10.41 0.845 3.20 0.027 0.038 ves

(WL0

> 60 2.97 11.24 0.941 3.56 0.021 0.031 ves

80 3.25 12.30 0.991 3.75 0.016 0.016 ves Partial 15 2.67 10.11 1.089 4.12 0.030 0.049 ves Quant. 25 2.77 10.48 0.988 3.74 0.025 0.031 ves

A A0 2.96 11.20 1.001 3.79 0.018 0.025 ves

<vl3) _ 60 * 3.24 12.26 1.041 3.94 0.014 0.018 ves 80 3.57 13.51 1.118 4.23 0.0078 0.010 ves Full 15 3.85 14.57 1.279 4.84 0.0072

Quant

.

25 3.96 14.99 1.279 4.84 0.0051

A0 4.18 15.82 1.279 4.84 0.0030

60

80

4.48

4.87

16.96

18.43 „

1.279

1,2.?? ..

4.84 0.0013

0.0005

/

35
Table 6b. Concentration ratios of sodium bromide in the w.c. well,

before and after flushing

Test medium: 200 ml. of 4% sodium bromide (NaBr)

Rx - Concentration ratio in the first flush

R2 - Concentration ratio in the second flush

V - Wate? inflow to the W.C.

W - Water in the W.C. well in the second flush

P - Statis pressure in psi

Syphonic Action - Denotes whether syphonic action

took place in the second flush cycle

R1 " C cil - Cb )/Cql - Cb ) R2 - (C12 - Cb )/Cq2 - Cb ) Where:

"CM denotes NaBr concentrations

in ppm as follows:

Cb - Background concentrations

Cii - Before first flush

Cqi - After first flush

ci2 ” Before second flush

Cq2 - After second flush

Sample: A5 Water Exchange Test

Flush

V inflow W W.C. R1 r

2 Syphonic

P £al. nr. Ral lit. Action

Partial 15 3.07 11.63 1.11 4.20 0.017 0.014 yes

Quant. 25 3.04 11.52 1.11 4.20 0.012 0.013 yes

1 40 3.21 12.16 1.11 4.20 0.011 0.0099 yes

W-2) 60 3.54 13.42 1.11 4.20 0.0062 0.0068 yes

@0 3.86 14.63 1.11 4.20 0.0028 0.0028 yes

Partial 15 3.45 13.08 1.11 4.20 0.0089 0.0057 yes

Quant

.

25 3.61 13.68 1.11 4.20 0.0039 0.0044 yes

2 40 3.87 14.67 1.11 4.20 0.0031 0.0028 yes

(WLX ) 60 4.25 16.10 1.11 4.20 0.00094 0.0012 yes

80 4.62 17.51 1.11 4.20 0.00043 0.00016 yes

Partial 15 3.86 14.63 1.11 0.0030 0.0043 yes

Quant. 25 4.02 15.24 1.11 0.0025 0.0037 yes

3 40 4.20 15.92 1.11 0.0022 0.0033 yes

cm-o) 60 4.56 17.28 1.11 0.00040 0.00058 yes

80 4.99 18.91 1.11 0.00026 0.00040 yes

Partial 15 -

Quant. 25 -

4 40 • (wl3 ) 60 '

80 - Full 15 4.59 17.40 1.11 0.00013

Quant

.

25 4.73 17.93 1.11 0.00026

40 4.72 17.89 1.11 0.00006

60 5.04 19.10 1.11 0.00010

80

36
Table 6c. Concentration ratios of sodium bromide in the w.c. well,

before and after flushing

Test medium: 200 ml. of 4X sodium bromide (NaBr)

Rj - Concentration ratio in the first flush

R2 ~ Concentration ratio in the second flush

V - Water Inflow to the W.C.

W - Water in the W.C. well in the second flush

P - Statis pressure in psi

Syphonic Action - Denotes whether syphonic action

took place in the second flush cycle

R1 “ ( cil ** Cb )/Cql - Cb ) R2 - (C12 - Cb)/Cq 2 - Cb ) Where:

"C" denotes NaBr concentrations

in ppm as follows:

Cb - Background concentrations

On - Before first flush

Cqi - After first flush

C* 2 - Before second flush

Cq2 - After second flush

Sample: CR5

Water Exchange Test

Flush

V inflow w w .C. R

1 R

2 Syphonic

P gal. lit. gal “lit. Action

Partial 15

Quant. 25

1 40 2.32 8.78 .698 2.64 .0506 .0938 nn

(WL2) 60 2.69 10.18 .993 3.76 .0296 .0333 ves

80 2.88 10.90 1.088 4.12 .0255 .0276 ves Partial 15 2.30 8.70 .890 3.37 .0494 .0644 ves Quant

.

25 2.30 8.70 .731 2.77 .0613 .1213 no

2 40 2.92 11.05 1.088 4.12 .0224 .0311 ves

(WLx) 60 3.23 12.23 1.088 4.12 .0206 .0215 ves

80 3.46 13.10 1.088 4.12 .0135 .0102 ves Partial 15 2.53 9.57 .865 3.27 .0447 .0378 ves Quant

.

25 2.69 10.18 .818 3.10 .0497 .0421 ves

3 40 3.38 12.79 1.088 4.12 .0168 .0161 ves

(W.0

> 60 3.63 13.74 1.088 4.12 .0102 .0095 ves

80 4.00 15.14 1.088 4.12 .0060 .0063 ves Partial 15

Quant. 25

4 40

(W.3)

_ 60 '

80

Full 15 3.55 13.44 1.088 4.12 .0154 ves Quant

.

25 3.83 14.50 1.088 4.12 .0094 ves 40 4.39 16.62 1.088 4.12 .0019 ves 60 4.77 18.05 1.088 4.12 .0003 ves 80 5.29 20.02 1.088 4.12 .0002 ves

37
Table 6d. Concentration ratios of sodium bromide in the w.c. well,

before and after flushing

Test medium: 200 ml. of 4% sodium bromide (NaBr)

IT - Concentration Tatlo In the first flush

K2 * Concentration Tatlo in the second flush

V - Water inflow to the W.C.

W - Water in the W.C. well in the second flush

P - Statis pressure in psi

Syphonic Action - Denotes whether syphon! c action

took place in the second flush cycle

R1 “ < cil - Cb )/Cql - Cb ) R2 * <ci2 “ Cb )/C

q2 - Cb ) Where:

"C" denotes NaBr concentrations

in ppm as follows:

Cb - Background concentrations

Cu - Before first flush

Cqi - After first flush

c12 “ Before second flush

Cq2 - After second flush

Sample: CR3

Water Exchange Test

Flush

V inflow w w .C. R1 r

2 Syphonic

P gal. lit. Jgal . lit. Action

Partial 15

Quant. 25

1 40

(W-2 ) 60

/

80

Partial 15

Quant

.

25

2 40

(WLX

) 60

80

Partial 15

Quant. 25

•

3 40

*

(W-o) 60 2.25 8.52 .906 3.43 .0467 .0971 no

80 2.51 9.50 .957 3.62 .0337 .0444 ypQ

Partial 15

Quant. 25 1.98 7.49 .568 2.14 .0706 .1034 nn

4 40 2.39 9.05 1.011 3.82 .0501 . 027R

'

(WL3) 60 * 2.60 9.84 1.088 4.12 _ .0440 .0381

80 2.88 10.90 ..L Q88 ... 4.12 .0223 (131 n 1L£L£ Full 15 3.01 11.39 1.088 4.12 .0182

Quant. 25 3.06 11.58 1.088 4.12 .mqn

40 3.39 12.83 1.088 4.12 .nmfi

60 3.66 13.85 1.088 4.12 .mm

80 3.89 14x22- 1.D88 . 4.12 -JQ053

38
'I

Table 6e. Concentration ratios of sodium bromide in the w.c. well,

before and after flushing

Test medium: 200 ml. of 4Z sodium bromide (NaBr)

Rj * Concentration ratio in the first flush

R2 ~ Concentration ratio in the second flush

V - Water inflow to the W.C.

W - Hater In the W.C. well in the second flush

P - Statls pressure in psl

Syphonic Action - Denotes whether syphonic action

took place in the second flush cycle

R1 - (Cn - Cb )/Cql - Cb ) R2 - (Ci2 - Cb )/Cq2 - Cb ) Where:

"C" denotes NaBr concentrations

in ppm as follows:

Cb - Background concentrations

Cn - Before first flush

Cqi - After first flush

Ci 2 - Before second flush

Cq2 - After second flush

Sample: A3

Water Exchange Test

Flush

V inflow W W.C. R1 r

2 Syphonic

P gal. lit. gal Ut. Action

Partial 15 —, _ Quant

.

25 2.22 8.41 0.898 3.4Q_ 0.026 0.197 no

1 40 2.36 8.94 0.999 3.79 0.033 0.167 no <wl2) 60 2.63 9.97 1.001 . 3.80 0.021 0.023 yes

80 2.92 U.QZ 1.110 4.21 0.015 1L.Q16.

.

ves Partial 15 2.49 9.44 0.954 3.62 0.033 0.073 no Quant

.

25 2.58 9.78 0.941 3.57 0.024 0.121 no

2 40 2.75 10.42 1.091 4.13 0.018 0.012 ves

(WLX ) 60 3.07 11.64 1.110 4.21 0.013 0.010 ves

80 3.37 12.77 1.110. 4.21 0.0076 0.0097 VPS

Partial 15 3.07 11.64 1.110 4.21 0.017 0.014 yes

Quant

.

25 3.04 11.52 1.110 4.21 0.012 0.013 ves

3 40 3.22 12.20 1.110 4.21 0.011 0.0098 ves

(VL0

) 60 3.54 13.41 1.110 4.21 0.0061 0.0068 ves 80 3.86 14.63 1.110 4.21 0.0028 0.0028 ves Partial 15 3.12 11.82 1.110 4.21 0.0064 0.0080 ves Quant. 25 3.28 12.43 1.110 4.21 0.0042 0.0068 ves

4 40 3.53 13.38 1.110 4.21 0.0044 0.0034 ves

(wl3) 60 * 3.80 14.40 1.110 4.21 0.0021 0.0022 ves

80 4.16 15.76 1.110 4.21 0.00091 0.0011 ves Full 15 4.41 16.71 1.110 4.21 0.00053

Quant. 25 3.78 14.33 1.110 4.21 0.0022 /

40 3.85 14.59 1.110 4.21 0.0022 X

60 4.07 15.43 1.110 4.21 0.0015

80 4.28 16.22 1..U0 — 4,-21 0.00064 \

39
Table 6f . Concentration ratios of sodium bromide in the w.c. well,

before and after flushing

Test medium: 200 ml. of 4Z sodium bromide (NaBr)

Rx - Concentration ratio in the first flush

R2 - Concentration ratio in the second flush

V -- Water inflow to the W.C.

W - Water in the W.C. well in the second flush

P - Statis pressure in psi

Syphonlc Action - Denotes whether syphonlc action

took place in the second flush cycle

R1 “ < cil " Cb )/Cql - Cb ) R2 “ <Ci2 “ Cb )/Cq2 - Cb ) Where:

"C" denotes NaBr concentrations

in ppm as follows:

Cb - Background concentrations

Cn - Before first flush

Cqi - After first flush

Cf2 - Before second flush

Cq2 - After second flush

Sample: K3

Water Exchange Test

Flush P

V inflow w‘ W. C. R1 R

2 Syphonic

gal. lit. gal nr. Action

Partial 15

Quant. 25

1 40

<VL2 ) 60

80

Partial 15

Quant

.

25

2 40

(WLX

) 60

80

Partial 15

Quant. 25

3 40

(WL0 ) 60

80

Partial 15

Quant. 25

4 40 1.84 6.96 .576 2.18 .0495 .1593 no

(wl3) 60 * 2.09 7.91 .620 2.34 .0313 .0449 yes

80 2.37 8.97 .704 2.66 .0176 .0265 yes

Full 15 3.03 11.47 .972 3.68 .0014

Quant. 25 3.21 12.15 .972 3.68 .0041

40 3.39 12.83 .972 3.68 .0021

60 3.77 14.27 .972 3.68 .0006

80 4.06 15.37 .972 3.68 .0002

40
Figure 6. Relative concentration ratio ’R’ as a function of the water

usage per flush cycle for the water closet samples tested

41
Table 7 . Water Exchange-Relative Concentration Values for

European Water Closets

Sample Volume in liters

Group Identification of water in well Flush volume in liters

9.0 7.5 6.0 4.5

A 1.75 0.007 0.009 0.023 0.135

D 1.91 0.010 0.015 0.026 0.074

A

F 1.82 0.013 0.023 0.042 0.052

H 2.42 0.031 0.043 0.066 0.123

8.0 7.0 6.0 4.0

r4 1.19 0.001 0.001 0.001 0.005

Y

8 2.16 0.002 0.002 0.012 0.036

B n

9 1.87 0.001 0.001 0.006 0.028

H

5

2.18 0.003 0.013 0.032 0.089

Note: Samples I^, Yg, N^, designate water closets manufactured by:

Italy, Israel, The Netherlands and Hungary

Group A: Prepared by Brunei University - England (Ref. 14)

Group B: Prepared by the Standards Institution of Israel (Ref. 15)
Figure 6. Relative concentration ratio 'R* as a function of the water

usage per flush cycle for the water closet samples tested

41
Table 7 . Water Exchange-Relative Concentration Values for

European Water Closets

Sample Volume in liters

Group Identification of water in well Flush volume in liters

9.0 7.5 6.0 4.5

A 1.75 0.007 0.009 0.023 0.135

D 1.91 0.010 0.015 0.026 0.074

A

F 1.82 0.013 0.023 0.042 0.052

H 2.42 0.031 0.043 0.066 0.123

8.0 7.0 6.0 4.0

h

1.19 0.001 0.001 0.001 0.005

Y

8 2.16 0.002 0.002 0.012 0.036

B n

9 1.87 0.001 0.001 0.006 0.028

H

5

2.18 0.003 0.013 0.032 0.089

Note: Samples I^, Yg, N^, designate water closets manufactured by:

Italy, Israel, The Netherlands and Hungary

Group A: Prepared by Brunei University - England (Ref. 14)

Group B: Prepared by the Standards Institution of Israel (Ref. 15)

42
Relative

Concentration

10

1

10

1

os

10

10

10

c—

i

f

W.C

R - VoV -

F -

Sasp]

0.90

Total Water

flush

Total

flush

—

V/0 . 6^ e bowl after

In the

Vo)

's we]

the

1

/^

• •/

/ •+

.a

*• y

/+

• + /

• /

* /

t/ —

e: B; Vo/V)

watei

In the cycle water

cycle

Exp (' In tl bowl

: usage

/ — • -

•m —— — —/

•

w.c Samp .e: A3

- — —• /. ... . ... 4'J R «= 0.75 :v0

/v) Exp (• 4* 0 O' V0 )

.... J -f /

/ j i* *

1

i

!

•f-

. - - +

* - ... —

'

i

: ..

. . . .

: • : . - •'

: - ^

.

:• . — — .....

• ~

. . _ . . . . _ .

18 16 14 12 10 8 6

Water Usage in Cycle (L)

Figure 7. Water exchange test

derived equation

comparison of laboratory data and fitted

43
Mathematical Modeling

A mathematical expression for describing the water exchange in the bowl was derived on the basis of some assumptions and evaluated with the laboratory test

data. Details of the derivation are described in Appendix B.

The water exchange may take place with the following processes at different

time intervals during the total flush cycle:

a. Apparent piston action

The fresh water flowing to the bowl displaces the water in the bowl

which flows out.

b. Instantaneous mixing

Each fresh water quantity which enters the bowl is immediately mixed

with the total water in the well.

c. Complete mixing prior to discharge

Discharge takes place only after mixing of the incoming water and the

water in the well.

d. Complete mixing with no discharge

This process actually takes place toward the end of the flush cycle. As

siphonic action ceases, the water remaining in the trap mixes with the

refill fresh water which fills the well to its weir level.

These assumptions lead to the following expression for the water exchange

process:

R

1 - *1 CV“>e 'VK2Wo where:

is the relative concentration ratio (dimensionless)

V

Q is the total water usage in the flush cycle (volume units)

VJ is the volume of water in the well to the weir

o W is the volume of water in the well after the flush cycle (W < W

Q

)

and are constants which are evaluated by the laboratory test data,

with the use of the method of "least squares."

44
In tables 8a and 8b and figure 7, a comparison between the values obtained

with this equation and the laboratory test data are indicated. This

expression leads to a reasonably good agreement with the laboratory data for cases for which siphonic action took place in the bowl. In the absence of

siphonic action in the flush cycle, this expression is not valid.

45
Table 8a. Concentration ratios before and after flushing - comparison

between laboratory data and results obtained by empirical

equation

Water Exchange Test

R1 L- _ TCJLab.

Data

Empirical Equation r Lab.

Data

Empirical Equation

Method

2nd • Method

1st,

Method

2nd

Method

0.102 0.100 0.099 0.497 0.223 0.049

0.090 0.094 0.094 10.438 0.180 0.031

0.070 0.078 0.077 0.377 0.152 0.022

0.047 0.054 0.054 j 0.284 0.131 0.016

0.038 0.042 0.041 ! 0.056 0.079 0.0056

0.065 0.061 0.061 j 0.422 0.219 0.047

0.065 0.059 0.058 10.384 0.196 0.037

0.052 0.048 0.048 | 0.298 0.168 0.028

0.039 0.035 0.035 | 0.064 0.150 0.021

0.026 0.021 0.021 ! 0.035 0.134 0.017

0.024 0.033 0.032 0.071 0.204 0.040

0.033 0.031 0.031 0.049 0.168 0.027

0.027 0.026 0.025 0.038 0.137 0.018

0.021 0.017 0.016 0.031 0.145 0.020

0.016 0.011 0.010 0.016 0.134 0.017

0.030 0.022 0.022 0.049 0.219 0.049

0.025 0.021 0.021 0.031 0.178 0.031

0.018 0.016 0.016 0.025 0.261 0.025

0.014 0.010 0.010 0.018 0.148 0.020

0.0078 0.0059 0.0059 0.010 0.141 0.019

0.0072 0.0035 0.0034

*

0.0051 0.0030 0.0029

0.0030

; . . . . 0.00.21 0.0021

jo. 0013 0.0014 0.0014

0.0005 0.0008

. . .4 0.0008

Cl 0.90 0.90 Cl 0.93 0.93

C2 0.54 0.53 C2 1.69 0.83

Sample Bi

Equations :

RX s (Cq

1

-Cb )/(Cil - Cb )

R2 = (Cq

x - C

b

)/(Ci 2 - Cb)

Cb » Background concentration

of sodium bromide

Ci, = Initial cone.- first

1

flush

Cq^ * final cone. after flush

Ci 2 - Initial cone.- second

flush

Cq

2 - Final cone. after flush

R = C

;i (Vo/V) exp (-F/C

2 V)

Vo - Volume of water in W.C.

up to weir

V - Volume of water cn W.C.

before flushing

F - Total flow in flush cycle

C

l'

C

2 ~ Coe ffi cients to be

evaluated

Subject to :

By 1st method:

nURlab

- R) - E - min

i^i

By 2nd method:

n

I (R

icl

2 2 lab - R) /R

lab

- E = min

46
Table 8b. Concentration ratios before and after flushing - comparison

between laboratory data and results obtained by empirical

equation

Water Exchange Test

R1

1 £R2

Lab.

Data

Empirical Equation Empirical Equation

1st

Method

2nd

Method

Lab.

Data

1st

Method

2nd

Method

- - - -

l

1

1 0.026 0.039 0.030 0.197 0.061

0.033 0.029 0.021 0.167 0.068 I 0.021 0.020 0.014 0.023 0.051

11

0.015 0.012 0.0083 (0.016 0.051

0.033 0.026 0.018 0.073 0.052

0.024 0.023 0.016 0.121 0.046 1

j 0.018 0.015 0.011 0.012 0.058

! 0.013 0.010 0.007 0.010 0.045

0.008 0.006 0.004 0.010 0.037

0.017 0.010 0.007 0.014 0.047

0.012 0.010 j 0.007 0.013 0.046

0.011 0.008 0.005 0.010 0.039

0.006 0.005 0.003 0.007 0.028

0.003 0.003 0.002 0.003 0.021

0.006 0.009 0.006 0.008 0.043

0.004 0.007 0.004 0.007 0.037

0.004 0.005 0.003 0.003 0.029

0.002 0.003 0.002 0.002 0.022

0.001 0.002 0.001 0.001 0.016

0.000. 1 0.001 0.0008

0.002 0.004 0.002

0.002

0.002

0.003

0.002

0.002

0.0014

><

0.000 > 0.0017 0.0010

Cl 0.75 0.75 Cl 0.80

Cl 0.64 0.58 C2 0.96

Sample A3

Equations :

*1 = (Cq

1

-Cb )/(Cil - Cb

)

*2 ' CGq^ - Cb

)/(Ci 2 - Cb)

Cb « Background concentration

of sodium bromide

Ci. « Initial cone.- first

flush

Cq^ = final cone, after flush

Ci

2 = Initial cone.- second

flush

Cq

2 = Final cone, after flush

R = C^ (VoA) exp (-F/C

2 V)

Vo = Volume of water in W.C.

up to weir

V = Volume of water cn W.C.

before flushing

F = Total flow in flush cycle

C^, C

2 = Coefficients to be

evaluated

Subject to :

By 1st method:

n

I (R

i=l

lab

E = min

By 2nd method:

nZ(R

lab - R)

2 /R

i=l i

2lab

E = min
4.4 Test of Paper Removal

Table 9 indicates the results of the Paper Removal Test as carried out

according to the test procedure described in Section 3.4. Similar results were obtained with all the water closet samples, from which, the following

conclusions were drawn:

- As long as siphonic action takes place in the bowl, all the paper load is

removed from the water closet.

In the absence of an adequate siphonic action, the toilet paper is not

evacuated from the bowl.

The requirement that the water closet must be capable of removing the toilet

paper load at all times is reasonable, although it may stem from aesthetic

reasons only. The above conclusions indicate that there is no need for a performance test of paper removal since an adequate siphonic action will remove

the paper wastes, and with the absence of an adequate siphonic action, the paper

wastes will not be flushed out.

4.5 The Rim Wash Test

The methods considered for testing the adequacy of the rim wash were described

in Section 3.4. The problems experienced with these methods were in the area

of elimination of subjective judgment, repeatability of results, simplicity of

preparation of the test medium, and problems in quantification and rating of

the results.

Table 10 summarizes the results of a rim wash test as obtained by the "dots

test," "line marking test" and the "saw-dust test." No attempt was made to

statistically evaluate the repeatability of the results. The saw dust test was considered unsatisfactory because the outcome of the tests yielded results

which required undue subjective judgement since particles of saw-dust remain on the bowl surfaces and the observer finds it difficult to evaluate the results

even on a basis of a pass/fail criterion unless the requirement calls for a complete removal of all particles from the bowl surfaces. The results of the

dots test and lines test are reasonably satisfactory since the outcome of both

tests can be quantified. The repeatability of the results has not been satisfactory. This can be improved by using a better test medium for yielding more

consistent results.

These tests were performed by marking the dots and lines with a water

soluble paint with an 1/8" brush. A better medium (used towards the end of

the laboratory work) was a thin water soluble felt-tip pen which yielded

more uniform marks. This medium was used in the subsequent experiments for

the single line test and enable a higher mode of uniformity in drawing the

line, with some improvement in test reproducibility.

48
Table 9. Test of Paper Removal

Result of Test Runs

Test Load : Six double

measured 4

strips cut from a 1/2 x 4 1/2".toilet paper roll. Each strip

The paper is placed in

repeated for a load of

results were obtained.

the bowl,

12 double

and the

strips

.

toilet flushed. This procedure was Except for two flush cycles, identical

Water

per

First Run Second Run

Flush

Cycle

l

1st flush

cycle

2nd flush

cycle

Siphonic

Action

1st flush

cycle

2nd flush

cycle

Siphonic

Action

6.8 0 6 no 0 6 no

7.0 0 6 no 0 6 no

7.7 0 6 no 0 6 no

7.9 0 0 no 0 0 no

8.3 0 6 no 0 6 no

8.5 0 6 no 0 6 no

8.9 0 6 no 0 6 no

9.3 0 0 yes 0 6 no

9.4 0 4 no 0 4 no

9.5 0 0 yes 0 0 yes

9.8 0 0 yes 0 0 yes

10.2 0 0 yes 0 0 yes

10.8 0 1 yes 0 0 yes

11.5 0 0 yes 0 0 yes

11.9 0 0 yes 0 0 yes

49
Table 10. Rim Wash Test

Experiments with three methods:

Dots marking test 1/8" dots spaced 1/2" apart were marked in the bowl with

water soluble paint. The numbers in the table represent the number of unwashed

dots after the flush cycle.

Line marking test 1/8" lines were marked on the circumference of the bowl

spaced 3/4" apart vertically with the paint medium as for the dots test. The

numbers in the table represent the total number of 1/4" marks not washed in the

flush

.

Saw-dust test The bowls surface was wetted and fine saw dust was sprayed by

hand in the bowl up to a level of 3/4" from the rim. The numbers in the table

represent the total number of 1/2 x 1/2" squares not flushed in the flush cycle.

Line

Pressure

Water

Usage

Dots Marking Test Line Marking Test Saw Dust Test

Partial Flush Quantity

kPa Psi l

1 2 Runs

3 4 Mean 1 2

Runs

3 4 Mean | 1 2

Runs

3 4 Mean

103 15 7.0 4 3 4 5 4 9 7 14 10 10 | 1 0 1 0 0.5

276 40 7.9 3 2 4 3 3 6 9 5 5 6 | 1 0 0 0 0

552 80 9.8 3 3 2 1 2 6 4 6 5 5 | 1 1 0 0 0.5

Total Flush Quantity

103 15 14.6 3 3 4 3 3.5 5 4 6 5 1 o 0 0 0 0

276 40 15.9 2 1 1 3 2 * 2 5 5 4 1 o 0 0 0 0

552 80 18.3 2 5 0 3 2 4 4 6 5 4 1 o 0 0 0 0

50
The preparation of both lines and dots tests turned out to be a rather laborious

task. It was therefore decided to test the water closet samples by the method

adopted by the revised ANSI A112.19.2 Standards, called the "Ink Test" as described in Section 3.4.

Table 11 describes the results obtained with tests of three water closets. An

adequate rim wash, depends primarily upon the proper distribution of the rim

holes, and only to a small extent on the quantity of water used per flush cycle.

This is seen in the small change in the rim wash effectiveness with increased

water in the flush cycle. This conclusion may not apply to all water closets,

and therefore this line mark test is necessary for testing two-step flush

devices for the adequacy of the rim wash also for partial flush cycles.

51
Table 11. Rim Wash Test - The Ink Test

Test Results of Three W.C. Samples Tested.

Test procedure as described in the revised ANSI A112.19.2 Standard:

Test medium: A fine tipped felt pen containing a dark colored water soluble

ink.

A line is drawn around the circumference of the bowl one inch below the rim.

The bowl is flushed and the total length of the remaining unwashed line segments

is measured in inches. Measure to the nearest 1/8 inch.

W.C. Flush Flush Per Total Length of Unwashed Line Segments

Cycle Cycle

Jt (in)

Run 1 Run 2 Run 3 Run 4 Mean

CR-> Full 11 .5 1/2 1/2 1 1/4 1/2

Flush 12.8 -1/4 0 1 1 1/2

13.8 1/2 1 3/4 1/2 3/4

Partial 8.9 1 1/4 2 1 1/2 11/2 1 5/8

Flush 9.4 1/2 1 1/2 1 2 1 1/4

10.9 1/2 1 1/2 3/4 3/4 1 H Full 11 .5 1/2 1/2 1/4 0 1/4

Flush 12.9 1/4 1/8 1/8 1/8 1/8

15.4 0 0 0 0 0

Partial 6.9 3/4 3/4 1/4 3/4 1/2

Flush 9.1 1/4 1/4 1/4 1/4 1/4

K

3 Full 13.0 0 0 0 0 0

Flush 14.5 0 0 0 0 0

16.0 0 0 0 0 0

Partial 11 .1 1/4 0 1/2 1/8 1/4

Flush 11 .8 0 0 0 1/8 0

12 .5 0 0 0 0 0

52
4.6 Tests of the Two-Step Flush Devices

The purpose of testing the manufactured two-step flush mechanism devices was to

study the mode of operation and observing typical problems which may effect

their performance. The tests were not intended for making a comparison among

the existing available systems in the market.

Appendix B describes the mechanisms which were available at the time of the

laboratory testing.

Test Results

Sample M-

^ This device is designed to replace only the flapper valve in the existing

flushing mechanism in the toilet. Installing this device in the water closets

revealed the following:

- Leakage through the valve. The flapper valve would not rest properly on the

tank outlet base and water leaks to the bowl.

Inconsistencies in delivering fixed water quantities. The following table

shows partial flush quantities as obtained in a partial flush cycle for one water closet sample. The following table indicates a typical distribution

of flows to water closet under testing.

Sam]pie B-, - Partial Flush Cycle

Cycle

Gallons

No. | 13.402

3.02

3

3.34

4

2.90

n| 2.77

Liters 12.8 11.4 12.6 11.0 | 10.5

In addition to these inconsistencies, the volumes of flush water are relatively

large. There are three adjustments in this device. Prior to testing, the

device was set to deliver the minimum flush quantities. This device was disqualified for further testing.

Sample M

2

This device is designed to replace the whole flushing mechanism in the tank,

except for the existing overflow arrangement, and is composed of intricate

components and parts to obtain the desired full and partial flush cycles.

The following features were observed:

Complexity of installation. Difficulties were encountered in a .igning all

parts of the mechanisms

53
- Leakage through the flush valve. All the toilet samples tested with this

device experienced leakage through the valve to varying degrees. This

device was disqualified for further testing.

Sample

This device is designed to completely replace all the parts of the existing

mechanism. This in itself is an advantage since this device is not dependent

on existing parts in the tank and is installed as a complete flush valve unit.

The undesired feature of the device is that the tank must be disassembled prior

to installation. This device could not be tested in two water closets. In the

first one, the mechanism of the device interferred with the float of the ball

cock. In the second one, its total height exceeded the height of the water

closet tank.

Samples M, and were obtained upon termination of the laboratory test, and

are only described in Appendix A.

Tables 11a through lid describe the test results of mechanism as performed

with four W.C. samples, where the following findings may be summarized:

Siphonic action is not obtained for partial flush quantities up to 10 liters.

Paper removal is not attained in the absence of a fully developed siphonic

action.

- Poor water exchange occurs in the absence of siphonic action.

Results of the laboratory tests indicate the following problems with the

selected samples: Incompatibility of the devices with existing water closets

which results in impossibility of installation, leakage through the flush

valve, and inconsistency in delivering constant quantities of water per full

and partial flush cycles.

54
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55

The

nomeclature

is

the

same

as

for

Table

3.

Pellets

test

was

performed

for

the

1st

and

2nd

flush

cycles
0)o

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a) Q

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COIo&H3

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to COa

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cu jH

cuS

to co

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CJ

m t-- co o 0)

X r- r-H o o o 4-> w Oi o o o o 04 o o o o T3

Ju • • • • 04 o o o o 4-4

4-4 o 3 3 3 | o o o o O 3 si

SZ o o o o o o 3

•H

T33

CO CM CM CO o o o 4-1 3 rH

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04 0) rH o rH o o o

CL, es rH

SZ

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•H 33

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33

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rH

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to OC • • • • • PU CM CM CM CO CO # •H M 4-1 3 m m o o o M Pu CU rH CM lO 00

56

The

nomeclature

is

the

same

as

for

Table

3.

Pellets

test

was

performed

for

the

1st

and

2nd

flush

cycles.
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4J COo&H

cd X

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4-1 Pm

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rH

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57

No

siphonic

action

on

1st

flush.

Pellets

test

was

performed

in

the

first

flush

cycle.
Table

lid.

Summary

of

the

Tests

Carried

Out

With a

Two-Step

Flush

Device

En

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t/3 u

4-1 3

to3

O'

33

to3

r—I

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X

X o 3 3

34 Pi 3 in

m st st

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CM 3 rH 3 rH rH 3 . W ES

to rH 3H CM CM

CD ^S„ rH o

60 CO St OD 33 3 rH

u s CM 00 00 CO CM to 3

(1) CO

H o o o o 3 35 rH

4J 33 rH o o o o o 3

to o pi • • • • • o o o o o S *H CM CM w •H

P5 3 rH iH

rH 3 1

3S rH %

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x

Xu i 1 I 1 1 3 3 33 33

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•H

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to * 3 m iD CO rH CM 33 b-s ME B-S

4-> 3 CM

W * 3 o O

O o 3 *r4 +J 3 CM i o O 03 00

«H Cd 3 -H tH rH <H s 4-) rH Cd

0) 0} ton in St tH rH

h

a 4-j Pm PS rH 3 3 CO o X

O <r

Pm 0e3 <H o rs

m rH

n

X to to CO to CO 3 4-1 CD 3 3 3 3 O st Jo to En tn En 33

•H 3 4-1 CO 4-> O st 3

CJ 33 to CO CO to CD •H En <5 U CD 3 3 3 3 4-) CO to En En E*> En O "0 o <5 Pm CO •H X CO 3 3 33 CO CO CO CO to CO 3 En O 3 0) 3 3 3 3 3 •H

33 CM >. En En Es En rH 3 33 a Pm O 3 o o o 3

•H 33 CM 3 3 3 3

to 4-1 to CO to CO CO <4-1a En

to 3 3 3 3 3 o •H

lH En En En En El C/3 4-> En CO o 3 3 CO

w

4-1 rH 3 3 3 3 3

•H En En Es E-> • CM 00 CO <r CM 4->

4-) rH 00 00 CM in 3

•H • • • e • 3

rH CM CM CO in DO 3 • CM CO M3 in 00

rH pH rH rH rH O' 4J in ON 03 rs CD

•H • • • • • rH

cd •H

rH dO 33 rs 00 CD 3 o o in CM X & rH CM sr do o cn 4-1 CM CO o rH co 3 • • • • P4 rH 00 rH CO X

60 CO CO CO st 3 3 • • • • • Pm 60 rH tH CM CM CM

•H • •H 1 4-1 CO in in o o o M 4-> co in in o o o

PL, 3- ?H CM St vO 00

H CM CD rH CM <fr

X 00 1

58

Pellets

test

was

performed

for

the

first

and

second

flush

cycles.
5. RECOMMENDED CRITERIA AND TESTING PROCEDURES FOR TWO-STEP FLUSH DEVICES

FOR SIPHONIC WATER CLOSETS

The following test procedures are prepared as recommendations for voluntary

consensus standards and are based on tests conducted at the National Bureau

of Standards' Plumbing Research Laboratory. These tests were performed with

siphonic water closet bowls presently marketed by the major U.S. manufacturers.

The water closet samples included 5 gallon and water conserving (3 1/2 gallon)

systems of the "close-coupled" type. These samples were tested in combination

with two-step flush devices which were separately acquired and installed in

the water closets for the evaluation of their capabilities and limitations.

The following criteria and testing procedures of two-step flush devices may be

incorporated in one or more standards for sanitary fixtures. These recommendations were prepared with the initial intent to supplement the revised ANSI

A112.19.2 Standard and, as such, reference is made to the nomenclature and the

test procedure in that document.

5.1 Categories of Two-Step Flush Devices

At present, two step flush devices are marketed as distinct systems for the

replacement of the existing hardware in the toilet tanks. As such, they are designed for a specific type and model of a water closet available in the

market. Therefore, their design may be categorized as follows:

a. Designed to provide means for geometrical lateral and vertical adjustment

to facilitate installation and operation for any water closet.

b. Designed to provide means for adjusting the full and partial water quantities flushed per cycle.

c. No means for adjustment for installation, operation, or total flows per

flush cycle.

If the device does not meet categories a and b, the device should be tested

with the water closet for which it was designed. If the device meets categories

a and b, it should be tested with three water closet bowls. The device will

undergo all the tests described in Article 5.4 when connected to one out of the

three selected water closet samples. For the other two water closet samples,

only the tests prescribed in Articles 5.2.4 and 5.2.5 will be carried out.

The water closet to which the device is installed shall comply with all the

requirements as stated in the appropriate standard such as ANSI A. 112. 19 when

this water closet is tested with its original flushing mechanism for the full

flush cycle.

59
5

.2

Criterion For Two-Step Flush Devices

5.2.1 General

The device shall be designed and constructed for delivering two distinct

quantities of water to the water closet bowl.

The device shall be provided with means for a simple selection of the mode of

operation for the choice of the appropriate flush cycle.

The device, as installed, shall not interfere with the function of any remaining

pre-existing mechanisms in the water closet tanks, such as the water flow from

the water supply, ball cock operation, and water level control.

5.2.2 Mechanical Performance of Two-Step Flush Devices

The mechanism and all its parts shall be of sound construction and composed of

materials capable of withstanding the forces acting on the system in a normal

operating mode of full and partial flush cycles.

5.2.3 Watertightness of the Flush Valve

No leakage shall occur through the flush valve during the filling of the tank

and after termination of the flush cycle when the water in the tank has reached

the "Water Line."

5.2.4 Consistency in Delivering Full and Partial Flush Quantities

The nominal full and partial flush quantities of water shall be consistently

delivered for consecutive flush cycles with deviation that will not exceed

500 ml (0.13 gallons).

5.2.5 Hydraulic Performance - Siphonic Action

This test shall be carried out for conventional siphonic water closet bowls.

5. 2. 5.1 Full Flush Cycle

A siphonic action shall follow a full flush cycle at all times.

J 5. 2. 5.

2

Partial Flush Cycle

A siphonic action shall follow a partial flush cycle for at least four consecutive flush cycles.

5.2.6 Trap Seal Retention

Upon termination of the partial or full flush cycle, the trap seal depth in the

bowl shall not be reduced by more than 25 mm (one inch).

60
5.2.7 Removal of Liquid Wastes - Water Exchange

5. 2. 7.1 For each full flush, a dilution ratio of at least 100 shall be

obtained

.

5. 2. 7. 2 For each partial flush, a dilution ratio of at least 25 shall be

obtained.

5.2.8 Paper Removal for Partial Flush Cycles

The paper load appropriate for application when urine removal only is required

shall be removed from the water closet bowl upon termination of the partial

flush cycle.

5 .2 .9 Rim Wash

The mode of flushing attained by the two-step flush device shall not be degraded

as basically provided by the design of the rim jets in the water closet to reach

all the exposed surfaces in the bowl. In the method of testing as prescribed in

Section 5.3, the total length of ink line segments remaining on the flushing

surface shall not exceed 50 mm (2 in) and no individual segment shall be longer

than 12 mm (1/2 in), for the full and partial flush cycles.

5.3 Test Equipment and Apparatus Set Up

The equipment and apparatus for the water closet tests are as specified in the

revised ANSI A112.19.2 Standard. Additional optional instruments for the

water exchange test are specified in Section 5.4.3.

Mount the device into the tank of the water closet tested following the manufacturers instructions. If the devices contain several discrete possible adjustments

for attaining partial flush quantities, test and report the results for all the

set ups. If the device can be adjusted for delivering a continuous range of

partial flush quantities, select and test for three discrete quantities.

If the ball cock can be adjusted, it is recommended to adjust the ball cock such

that it closes at the marked "Water Line" in the tank for a static pressure of

the water supply of 40 psi (276 kPa)

.

No test is required for the removal of paper wastes. It has been

established in the laboratory tests at the National Bureau of Standards

Laboratory that an adequate siphonic action in the bowl will evacuate

the paper load.

2 A "life test" assembly and apparatus is required for the test specified in

5.4.6.

61
5 .4 Testing Procedures

Testing procedures will be carried out in the following sequence:

5.4.1 Watertightness of Flush Valve

Empty the tank of all its water content, fill the bowl to its weir level, and

disconnect the refill tube from the overflow pipe. Set the water supply static

pressure nominally to 40 psi^ (276 kPa) and place a one-liter vessel under the

bowl. Remove the vessel after the water in the tank has reached the water

level and replace by an empty dry vessel, for 20 minutes. The water volume in

the first vessel shall not exceed 100 ml (0.3 gallons), and no water shall be

observed in the second vessel.

5.4.2 Consistency in Delivering Full and Partial Flush Quantities

This test is performed for water supply static pressure conditions of 20 psi

(138 kPa) , and 80 psi (552 kPa) , ten times for each pressure. Adjust the water

supply pressure, allow sufficient time for the tank to be filled, and trip the

flushing device. Record the water quantity passed during the flush cycle, in a manner similar to the suggested Table 12. The "standard deviation" as defined

in Table 12 and calculated for ten flush cycles shall not exceed 500 ml (0.13

gallons) .

5.4.3 Siphonic Action and Trap Seal Retention

The following tests will be carried out for each water supply static pressure

of 20, 40, 60, and 80 psi (138, 276, 404, and 552 kPa)

:

5. 4. 3.1 Test for the Partial Flush Cycle

Make sure that the bowl is full to the weir. Open the water supply valve to

fill the water closet tank to the marked "water line". Observe and record the

flushing mode for attaining siphonic action.

Note: An adequate siphonic action is defined as that mode of flow which causes

the water level in the bowl to drop at least to the dip of the trap.

After flushing, measure the depletion of the trap seal height with reference to

the level of the weir.

With the water in the bowl left from the previous flush cycle, repeat four more

times to make up five partial flush cycles.

Test Criteria:

a. Siphonic action shall take place for at least the first four consecutive

partial flush cycles.

b. Maximum trap seal depletion shall not exceed 25 mm (1 in).

1 This pressure is adopted as reference value only.
5. 4. 3. 2 Test for the Full Flush Cycle

From the results of the tests for the partial flush cycle, determine the

maximum depletion of the trap seal.

If the value of the maximum trap seal depletion for partial flush is less than

5 mm (0.2 inches), there is no need for further testing. If the value is

larger than 5 mm

1

, perform the following tests:

5. 4. 3. 2.1 Fill the bowl to the weir. Remove water from the bowl to attain a trap seal height commensurate with the maximum trap seal depletion as obtained

in 5. 4. 3.1. Trip the flushing device to obtain a full flush cycle. Observe

for siphonic action. Repeat this test four more times.

Test Criteria: Siphonic action shall be attained for all the five flush cycles.

Record the findings of the tests in 5.4.3 in a form similar to the one as suggested in Table 13.

( 2 ) 5. 4. 3. 2 If the maximum trap seal depletion exceeded 5 mmv

, it is required to

repeat all the performance tests specified in an appropriate water closet

standard, e.g., ANSI A112.19.2, to ascertain that the performance of the bowl was not affected by the introduction of the device.

5.4.4 Water Exchange Test

The water exchange as determined by the dilution ratio is evaluated for two

consecutive flush cycles, both for the full and partial flush cycles. In the

first cycle, the water in the bowl is to its weir level and the test medium is

added to the well of the bowl. In the second cycle, the water in the bowl

remains as left from the first cycle and a new test medium is added for the

second flush cycle.

5. 4. 4.1 The Dye Test

The test is performed as prescribed in the revised ANSI A112.19.2, Article

5.4.5, where the criteria is as follows:

- A dilution ratio of at least 100 shall be obtained for the full flush cycle.

A dilution ratio of at least 25 shall be obtained for the partial flush

cycle.

1 A depletion in the trap seal up to 5 mm is unlikely to affect the performance

of the bowl in comparison to its performance with the original mechanisms.

2 A trap seal reduction of more than 5 mm may affect the performance of the

water closet in comparison to its performance with its original mechanisms.

63
5 . 4 . 4 . 2 Water Exchange With Sodium Bromide as Test Medium^

This procedure is proposed as an alternative to the dye test and may have its

merits in the following aspects:

- More accurate results as compared to the dye test

Relatively easy preparation of the test medium

- Materials and instruments:

pH conductivity meter

Electrodes for measuring concentrations of bromide ions in a sodium

bromide solution

Sodium bromide in crystal form

- Standard bromide solutions of concentrations of 2000 + 50 ppm and 5.0

+0.2 ppm. These solutions are required for the establishing of the

calibration curves as a basis for measuring the bromide concentrations

in the water exchange test.

Four to six 100 to 200 ml beakers

- 200 ml volumetric flasks

Test medium: Prepare a 4 percent, by weight, of bromide solution by

diluting 51 .5 grams of sodium bromide for each 1000 milligrams of distilled

water.

- Test dosage: A test dosage constitutes 200 ml of the 4 percent bromide

solution which is inserted in the bowl and thoroughly mixed with a stirring

rod for approximately 20 seconds.

Record the test results in a form similar to the one suggested in Table 14.

Calibrate the instrument with the prepared two solutions of known concentrations,

in parts per million (ppm).

It is desirable to prepare two more solutions whose concentrations are in the

range of the solutions to be used as a check on the calibration. The measured

concentrations should not deviate by more than 4 percent from their actual values.

Record the data in Table 15 in the columns on "Calibration" and "Verification.”

As discussed in Section 4.3 of this report, there are numerous ways for

evaluating the water exchange. A comparative evaluation of these methods is

still required.

64
A "test run" constitutes the following procedure which is performed for the

full and partial quantity of flush for water supply static pressures of 20,

40 and 80 psi.

Take two readings before the run and two after its completion for a mean

"background concentration."^

b. Make sure that the bowl is full to its weir. Add 200 ml of 4 percent NaBr

solution and mix thoroughly for 20 seconds with a stirring rod.

Take two samples from the bowl and read ppm.

Record results in column "Ci^"

c. Return samples to bowl. Flush the toilet. Mix water thoroughly; take two

samples and read ppm. Record results in column "C

d. Add 200 ml of 4 percent NaBr; mix thoroughly.

e. Repeat step b and record "Cqo"

f. Flush toilet twice and make sure seal trap is full to its weir for the

next test run pressure.

Calculate the average value of the sample pairs and calculate:

R

1

Repeat the above to obtain mean values for R^ and R

2 for each pressure.

Acceptance criterion: R-^ and R

2 shall not exceed 0.04.

5.4.5 Rim Wash Test

The test shall be performed as specified in the ANSI A112.19.2 Standard

Section 7. 4. 4.1, the Ink Test.

5.4.6 Mechanical Performance - Life Test

A mechanical assembly capable of performing the following automatic cyclic

operations should be connected to the two-step flush mechanism when the latter

is installed in the water closet tank:

1 "Background concentration" is the concentration of sodium bromide in the

water supply in the test facility at the time of testing the device.
Activate a full and partial flush cycle by tripping on the operating handle.

The total time per cycle (full and partial) should equal the total filling

time of the tank for a water supply static pressure of 80 psi (556 kPa)

.

The number of flush cycles should be: 20,000 for the full flush cycle and

80,000 for the partial flush cycle.*

Upon termination of the Life Test, the device shall be visually inspected

for the integrity of all its parts, such as fractures or deformations.

Tests 5.4.1 and 5.4.2 are then repeated.

This test simulates approximately ten years of service.

66
Table 13. Consistency of Water Delivered in the Full and Partial

Flush Cycles

^

- Water Usage Per Cycle - liter

Test

Number

10

Full Flush Cycle Partial Flush Cycle

20 psi-138 kPa I 80 psi-552 kPa 20 psi-138 kPa | 80 psi-552 kPa

1 Mean - Q | 10

Q = Z Qi | 1 10 |

1

Qi

-

1

1

1 q2 -

1

1

1

1

1 Q3 -

1

i

1

1

! qa -

1 Standard

deviation S s = - Q)2 | °1 =

1

1

|

o

2 =

!

1

1

| o

3 =

1

1

1 =

1 Criterion for passing: The values for o shall not exceed 500 ml (0.14 gallons)

67
Table 14. Test for Siphonic Action and Seal Trap Retention

Test for the Partial Flush Cycle

Total Pressure 1st Cycle 2nd Cycle 4th Cycle 5th Cycle

psi Pa

Siphonic

Action

Trap

Seal

Siphonic

Action

Trap

Seal

Siphonic

Action

Trap

Seal

Siphonic

Action

yes /no Loss yes /no Loss yes/no Loss yes/no

20 138

40 276

60 414

80 552

maximum seal trap loss:

Test for Full Flush Cycle

Total Pressure Run 1 Run 2 Run 3 4th Cycle 5th Cycle

Siphonic Trap Siphonic Trap Siphonic Trap

psi Pa Action Seal Action Seal Action Seal

Loss Loss Loss

yes/no mm yes/no mm yes/no mm

20 138

40 276

60 414

80 552

68
Table 15. Liquid Wastes Removal - Water Exchange Test

Instrument Calibration and Verification

CALIBRATION VERIFICATION - ppm

ppm st'd solution my reading Actual Measured Actual Measured

Background ppm: (C^)

P

psi

1

2

Test Cil 'qi ci2 Jq2

Cql C

b

C

il

- C

b

Cq2

~ C

b

Ci2 " C

b

Avg.

1

2

Avg.

1

2

Avg.

69
6 . CONCLUSIONS, RECOMMENDATIONS AND FUTURE RESEARCH

6 .1 Conclusions

The following conclusions related to two-step flush water closet closets were derived from the laboratory test results:

- Two-step flush devices may be installed in the ordinary siphonic water

closet bowls and provide satisfactory performance, provided the partial

flush cycle deliver at least ten liters (2.5 gallons) of water per flush

cycle (based upon the laboratory test data).

The two-step flush devices offer a partial solution to the problems of

water conservation for existing installed fixtures, and for fixtures which

will be installed in the near future. These devices may save water up to

40 percent when installed in 5-gallon water closets and up to 25 percent

when installed in 3.5 gallon water-saving toilets.

6 .2 Recommendations

- Test procedures for performance evaluation of two-step flush devices were established and are recommended to be incorporated into ANSI 112.19.2

standard or any other standard related to water closets.

- Efficient usage of the devices may be attained if their design is compatible

with the characteristics of the bowl and the ball cock in the tank into

which they are installed. A necessary feature to be introduced to the

system is a bowl refill control, so designed that its flow rate or total

flow would be dependent on the cycle mode, such that a partial flush cycle

will be followed by a larger refill flow rate (or total flow). This

arrangement will refill the bowl at all times, and preserve the integrity

of the consecutive flush cycle.

The large water consumption to the U.S. made water closets is attributed to

their present design stemmed from dimensional requirements of a large water

surface in the bowl and a deep trap seal. Other factors are a result of

consumer habits, life style and vogue. These features require a large

flow during the flush cycle and a large quantity of water for bowl refill

(up to three liters). A redesign of the conventional water closet where the

geometry of these features will be reduced can contribute to a substantial

reduction of water consumption.

The two-step flush devices offer a partial solution to the problems of

water conservation for existing installed fixtures, and for fixtures which

will be installed in the near future.

- For more substantial water conservation measures, manufacturers and

consumers should consider the introduction of the world-wide commonly used

European Flush Down water closets. Ordinary flush down toilets require

nine liters (2.4 gallons). Some water closets operate adequately with six

liters (1.6 gallons) and some innovative water closets operate with three

liters

.

70
6.3 Research

Water Exchange in Low Flush Water Closets. As specified in the revised

ANSI A112 .19 .2M-1980 Standard, "the water exchange shall affect a dilution

ratio of at least 100.” No information is available whether this dilution

ratio is necessary or sufficient in terms of disease transmission potential

It is expected that the "dilution ratio" will be much lower in low flush

toilets. A study is therefore required for establishing the "safe dilution

ratio" so that low flush, water conserving toilets can be evaluated for

biological safety levels.

Acknowledgements

The authors acknowledge the contribution of Mr. Jimmy James, Cooperative

Student from the Prairie View A&M University for his work in the laboratory experiments and data reduction, and Ms. Rebecca Meyer from the

Word Processing Center of CBT-NBS for her extensive aid in the preparation of this report.

71
7. REFERENCES

1. Residential Water Reuse

By: Murray Milne

California Water Resources Center

University of California/Davis

Report No. 46, September 1979

2. Wastewater Flow Reduction Study

By: Energy Resources Co., Inc.

Prepared for: Environmental Protection Agency

Washington D.C. Div. of Water Planning, October 1975

3. Management of Small Wastes Flows

EPA Publication 600/2-78-173, September 1978

4. Trials of Dual Flush Cisterns

By: A. Sobolev, A.M. Mech and C.J. Lloyd

Journal of Institution of Water Engineers

5. ANSI All 2. 19. 1M - 1980 (Sixth Draft)

Vitreous China Plumbing Fixtures

6. B.S. (British Standards) 1213 - Ceramic Wash Down

Water Closet Pans - 1975

7. B.S. (British Standard) 1125 - W.C. Flushing Cisterns - Including Dual Flush Cisterns and Flush Pipe - 1978

8. S.I. 146 (Israeli Standard) Water Closet Bowls

9. The Diffusion of Gases Through Water Seals of Plumbing Fixture Traps

By Robert S. Wily

NBS Report No. 102

June 1, 1951

National Bureau of Standards

10. Evaporation of the Water Seals of Plumbing Fixture Traps

By Robert S. Wily and Otto Hintz

NBS Report No. 1063

June 29, 1951

National Bureau of Standards

11. Review of Bacteriological Studies of Washrooms and Toilets with Particular

Reference to Reduced Flush Volumes

By M. F. Mendes - Rentokil Limited, Research and Development Division

Felcourt, East Grinstead, Sussex, U.K.

Paper delivered in the CIB Seminar, October 1978

72
12. Production and the Fate of Residual Organisms

By: C.P. Gebra, C. Wallis and J.L. Melnick

Department of Virology and Epideraology

Baylor College of Medicine, Houston, Texas

13. National Standard Plumbing Code - 1978

Contractors - Wash

14. A Study of the Interaction of Drainage System Loading and Reduced Flush

W.C. Operation

By: Dr. J.A. Swaffield, Dr. R.H.M. Wakelin

Drainage Research Group

Dept, Building Technology

Brunei University

15. Water Conservation Measures in Plumbing

The Performance of Water Closet Bowls of the Wash Down Type

Removal of Liquid Wastes

By: Prof. H. Ilberg, Eng. K.J. Zauker

Sponsored by the National Bureau of Standards

16. Water Conservation Measures in Plumbing

The Performance of Water Closet Bowls of the Wash Down Type

Laboratory Tests and Performance in Actual Use

By F. Winter

Sponsored by the National Bureau of Standards

17. Laboratory Work in Urine Analysis

By Fredrick G. Novy Sc.D. M.D.

George Wahr, Publisher

Ann Arbor, Michigan

18. Modern Urine Chemistry

A Guide to Diagnosis and Metabolic Disorders of Urinary Tract Diseases

AMES Company, Division of Miles Laboratories

Elkhart, Indiana 46514

73
Appendix A. Description of the Two-Step Flush Devices Tested

The following devices were acquired through manufacturers and distributors of

sanitary appliances:

Sample M-^

The mechanism is composed of a flapper valve which replaces the ordinary valve

in the existing flush valve assembly.

The valve consists of the following parts:

1.

Bulb (cup) - see Figure a

The bulb contains a 1/4” steel ball and a 3/16" hole at its bottom. A lid containing

four holes ranging in size from 1/32" to

1/8" is connected to the bulb's base. The

orientation of the holes in reference to

the bulb's hole determines the quantity 4of

water flowing out in a flush cycle.

2 . Ring and Collar - see Figure b

The valve is connected to the flush

mechanism by sliding its ring through the

overflow pipe such that it rests on the

overflow pipe base.

3 . Chain

The chain's hook is connected to the

flush mechanism's lift arm.

Valve's Operation

Figure b.

Flapper Valve

Figure 8.

Prior to normal operation, the valve has to be tried for its optimum

performance by setting the bulb's lid to its various position until a satisfactory flush is attained.

Attaining a Partial Flush

The flush handle is depressed as with an ordinary flush mechanism and released.

In this flushing mode, the (upward) buoyant force on the valve is stopped and

the valve falls down prematurely with the tank retaining part of its water.

Attaining a Full Flush

The flush handle must be slowly depressed and released. This mode of operation

will empty all the contents of the tank.

74
Sample

The mechanism replaces the ordinary flush valve and the flush handle assemblies

in the water closet tank. The system is composed of the following parts:

Rubber Valve (V)

Beads (B)

Float (F)

Float Catch (C)

Existing Overflow Pipe (OF)

Valve Positioning Adjuster (P)

Disc (D)

Control Arms (A^, A2)

Flush Handle Mechanism (H)

Valve's Operation

In its rest mode, float (F) is in its uppermost position and kept in place by

the hook at the end of the float catch (C).

Attaining a Partial Flush

The pull of the handle down will raise arm , which, in turn, will raise valve

(V) and at the same time the float catch (C) will release float (F). The float

will drop to the descending water level, will press on valve (V) and cause an early closure, thus attaining a partial quantity of flush. When flushing

ceases, the ascending water in the tank raises the float until it is locked in

place by the float catch. The number of beads above the valve control the float

travel distance and consequently the partial flush quantity.

Attaining a Full Flush

A pull of the handle down will raise arm A^ , which, in turn, will raise valve

(V) to empty all the tank's water content.
Sample

This mechanism replaces the whole flushing mechanism in the existing W.C.

It is composed of the following parts:

1. Flush handle (H)

2. Handle linkage (L)

3. Brace (B)

4. Rubber valves and overflows (V^ , V

2

) 5. Valves’ chamber

Mechanism's Operation

The mechanism contains two valves and

overflow arrangements which differ only

by the valve's height relative to the

water line in the tank.

Attaining a Parrial Quantity of Flush

By pushing handle (11) down, the handle

linkage (L) transforms the motion to brace

(B) which lifts valve from chamber C.

Attaining a Full Quantity of Flush

An upward movement of (H) lifts V

2 from C

to deliver a smaller quantity of flush

water

.

Installation of the mechanism requires the

removal of the tank so that chamber C can

be connected.

VI

76
Sample My|

The device is composed of the

following parts: (see figure)

1. Operating handle and rod

2. Shaft and chain

3. Valve (of elastomeric material)

4. Fastener (connection to the

overflow)

5. Two floats assembly

3

Figure 11.

The operating handle (1) replaces the existing handle in the tank. It contains

two actuating controls. The long sweep control will lift the shaft (2) higher

than the short sweep control. The fastener (5) is connected to the existing

overflow valve at an elevation which facilitates proper functioning of the system

and proper closure of the valve. When the tank is full, the buoyancy keeps the

two floats (4) up.

Attaining a partial flush

When the short sweep control arm is actuated, the valve will be raised to the

lower position. As the water in the tank drops below the upper float, early

closure of the valve will take place for the partial flush cycle.

Attaining a full flush

When the long sweep control arm is actuated, the valve will be raised to the

higher position, and will remain there until the full flush cycle ends.

77
Sample

The device is composed of the following

parts: (see figure)

Partial PI

1. Operating handle

2. Air hose

3. Flapper valve

A. Chain

5. Two floats

Handle

Partial Quantitiy Float

Full Quantitiy Float

Except for the existing overflow tube,

this device replaces the entire

flushing mechanism of the tank. The

handle contains controls for obtaining

a full and a partial flush cycle.

The floats may be moved to any level

for obtaining the desired quantities

of flush.

Overflow Tube

Figure 12

Attaining a Partial Flush

The front section of the handle is pressed down (see figure). This action

releases the partial quantity float mechanism. As the water level reaches this

float, air from the flapper valve rushes out and allows the flapper valve an early closure for obtaining a partial flush cycle.

Attaining a Full Flush

Both sections of the handle are pressed down. This action bypasses the upper

float and retains the flapper valve in an open position which enables a full

flush to take place.

78
Appendix B. B.l - Table 16. Water Exchange Test

Detection of Color in the Water Closet Bowl by Visual Examination

Test Procedure

Test medium: Erio Yellow T Supra, Acid Yellow, 023

Consol 19140, manufactured by CIBA-GEIGY

This medium was diluted with water to a concentration of 1:200 to

simulate the color of urine from which solutions were prepared

of the following concentration in reference to the above.

Solution A - 0.0000 - clear water

Solution B - 0.0010

Solution C - 0.0025

Solution D - 0.0050

Solution E - 0.0100

Two 200 ml samples were prepared for each subject (A^ .. Ag). These 10 samples were inserted randomly in the bowl and each subject was asked whether he

detected a change in color in the bowl, by:

yes - response to positive detection of dye

no - response to negative detection of dye

? - "not sure"

Sample

A B C D E

Person 1 2 1 2 1 2 1 2 1 2

A1 no no no no no no yes ? yes yes

A

2

no no no no no no yes yes yes yes

A3 no no no no no no no no ?

A4 no no no no no no ? no yes yes

A5 no no no no no no yes no yes yes

A6 no no ? ? yes yes yes yes yes yes

A7 no no no no no no yes no yes yes

A8 no no no no yes yes yes yes yes yes

Note

:

This test merely

drawing general

represents . conclusions

.

an indication and in no way is intended for
Appendix B2

.

Table 17. Comparison of "R" Value Results from Different Initial Concent rations

R =

C

q ~ C

b

C

i " C

b

I =

Cb

$

q

NaCl concentration of 200 ml test medium

Background concentration

Concentration before flushing

Concentration after flushing

I % NaCl

200 ml

C

b

PPM

in bowl

PP&

With Sam

PP&

After Flush

Ci-C

b

C -CK

q b

VC

b

R

Ci- Cb

1 37.4 596 56.1 488 18.8 0.038

2 32.8 946 66.6 913 33.7 0.037

3 35.7 1346 82.8 1310 47.1 0.036

4 35.6 1878 103.9 1842 68.3 0.037

Sample: B, , Testing a partial flush cycle with 2.3 gallons of water usage.

Tne results are means of four tests.

80
Appendix B3 . Water Exchange Test - Errors in Measuring Sodium Bromide Solutions

Comparison betweeen prepared (known) solutions and measured solutions.

Cp - prepared solution; cm measured solution

e Cm - Cp

Cp

.100

e = I C./30; S = /I (e. - e)

2

/

i=1 / 30

Note: This information is depicted from the test data obtained during the

period of testing the two step flush data.

Low Range Medium Range High Range

Cp Cm e Cp Cm e Cp Cm e 3.67 3.50 -3.42 121.1 119.4 -1.32 1331.9 1353.8 +1.64

3.67 3.65 -0.54 121.1 116.5 -3.80 1598.3 1660.0 +3.86

3.67 3.68 +0.27 121.1 126.6 +4.54 1598.3 1666.0 +4.24

3.67 3.78 +3.00 121.1 126.2 +4 .04 1598 .3 1675.9 +4.86

2.33 2.20 -5.90 121.1 125.4 +3.55 1141.6 1195.0 +4.70

0.88 0.91 +3.30 121.6 116.5 -4.19 1141.6 1073.4 -6.42

0.88 0.83 -5.68 121.7 119.6 -1.73 1141.6 1067.9 -5.95

0.88 0.84 -4.54 190.6 182.0 -4.51 1331.9 1289 .0 -3.75

3.15 3.04 -2.53 121.1 121.5 +0.33 1331.9 1355.4 +2.52

3.15 3.20 +1.58 121 .1 116.0 -4 .21 1141.6 1078.8 -5.59

3.15 3.06 -3.49 121.1 116.0 -4.21 1598.3 1601 .8 +0.22

2.54 2.49 -1.96 207.6 213.2 +2.69 1141 .6 1157.4 +1.38

2.54 2.44 -3.92 207.6 198.9 -4.23 1141.6 1162.9 +1.87

3.15 3.20 +1.58 108.3 103.5 -4 .43 1331.9 1336.3 +0.33

2.54 2.77 +5.11 108.3 110.4 +1.94 1141.6 1168.0 +2.31

2.54 2.78 +5.12 108.3 109.2 +0.83 1331.9 1301.5 -2.28

2.54 2.79 +6.84 108.3 113.1 +4 .47 1331.9 1293.1 -2.91

2.54 2.74 +6.84 108.3 101.3 -6.46 1141.6 1107.6 -2.98

2.54 2.74 +6.84 108.3 101.3 -6 .46 1141.6 1107.6 -2.98

2.54 2.60 +2.36 108.3 118.5 +7.40 1141.6 1201.2 +5.22

2.54 2.60 +2.36 108.3 118.5 +6.40 1141.6 1208.0 +5.82

1.57 1.48 -5.73 108.3 100.3 -7.41 1141.6 1199.9 +5.10

1.57 1.45 -5.64 108.3 117.6 +8.59 1331.9 1332.5 +0.05

2.54 2.56 +0.79 108.3 117.6 +3.97 1141.6 1198.2 +4.96

2.65 2.54 +4.33 108.2 112.6 +3.97 1331.9 1392.2 +4 .66

2.55 2.54 +0.39 108.2 112.9 +4.34 1331.9 1275.0 -4.27

2.54 2.59 +1.97 108.2 117.4 +6.50 1598.3 1547.6 -3.17

3.15 2.98 -5.39 121.1 124.1 +2.47 1331.9 1403.9 +5.41

3.15 3.19 +1.26 190.6 193.6 +1.57 2283.3 2354.5 -3.10

3.15 3.16 +0.32 202.8 206.8 +1.97 1141.6 1180.0 +3.47

2.54 2.73 +7.48 202.8 198.9 +1.92 1331.9 1327 .2 -0.20

e 0.21 1.11 0.73

S 4.11 4.34 3.89

81
B.4 Derivation of the Equation for Water Exchange

The water exchange in the bowl may take place with the following modes:

1. Piston Action

The fresh water coming from the tank completely displaces the contaminated

water in the W.C. well.

Defining:

W - Volume of water in the bowl

V - Volume of water flowing to and from the tank

C^ - Initial concentration in the bowl

Cq - Final concentration of the bowl upon termination of the piston action

C - Concentration of the fresh water

o Expressing the conservation of the mass contaminants:

V • c

o + wci = wc

q + vc

±

w-v v

C = • C, + « C for V < W

q v

1 w

°

Cq = C

G for V > W (Complete removal of contaminants)

This mode of flushing represents the ideal case since the fresh water will

completely replace the contaminated water as long as the volume of the incoming

water is equal or larger than the volume in the well.

2. Complete Mixing Prior to Discharge

V • C

Q + W • C

i = (V + W) C

q

V • C + W • C, o 1 C = — q v + w

3. Complete Mixing With Fresh Refill Water Upon Termination of Siphonic Action

Upon termination of siphonic action, the water in the bowl is W

g and its concen- tration C . The refill tube replenishes the well to a final volume of W, less

or equal to the total capacity of the bowl defined as W

Q

.

82
0 - V

t=t- At t=t- At

4. C

t =(w0 + / Qin dt - / Q0ut dt) • C

t _ At + V in out

• V Out• C

t = A t t-t G t- ti

t=t t=t

W

o + ' Qin dt ' 1 <W dt

t=t D t=t i

Assume the following events:

a. As flushing starts, unknown quantity of water flows with the initial

concentration by piston action, followed by the process of instantaneous

mixing described by expression A.

This unknown quantity, which is evacuated from the bowl by piston action,

will be expressed by insertion of a consent to be evaluated on the basis

of the laboratory data.

b. When the siphonic action ceases, the water remaining in the bowl undergoes

the mixing process with the fresh refill water as described in Process 2.

With disregard to the intermediate processes, the integrals in Equation A are substituted by "W" to be evaluated by the laboratory data:

^t ^t-At -Av

6

In differential terms

dv

The solution of Equation 7

8. C - K e "V/

( W

o “W

x)

for V = 0, C = C

o

C_ = C e Vs /(W0“ Wx ) s o

83
1 V

g is the flow volume to the bowl and C

g the concentration in the bowl upon

termination of the mode of instantaneous mixing. Let V

Q be the total flow to

the bowl. Then V = KV . where k is some unknown fraction.

Substituting the expression for "case 3", of complete mixing upon termination

of the siphonic action:

9 - C

f * C

oKl (U

o /W) e 'Vs/

( w

~w

x

)

- C

oK

l (W

o /W > e

~V0/ (W

Let Rn = CrVC the relative concentration ratio

i to

10. R

x = K

x (WQ /W) e ”Vo/ (K

2 W

q

)

K, and K

2 are constants which are evaluated from the laboratory test data, with

tne "least square" method by minimizing the following expression

n

Z (R.

laboratory

R

i y

^-equation

E

1 ^laboratory

'

Another scheme may be used for minimizing the

= E

following ratios

Z R, , R,

J-laboratory 1 equation

R.

-•-laboratory

2 = E

As the values of R range from 0.1 to 0.0001, the first scheme tends to minimize

the discrepancies of the large values obtained by the expression and the second

scheme has a tendency to minimize the small values.

84
NBS-114A (REV. 2 -80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

4. TITLE AND SUBTITLE

PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. NBSIR 81-2296

Publication Date June 1981

Criteria and Evaluation for Two-Step Flush Devices for Water Closets

5. AUTHOR(S)

Fred Winter and Lawrence S. Galowin

6. PERFORMING ORGANIZATION (If joint or other than N BS. see instructions) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State. ZIP)

Dept, of Housing and Urban Development

451 7th Street, SW

Washington, D.C. 20410

10.

SUPPLEMENTARY NOTES

J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here) Laboratory tests of two-step flush control devices for water closets were conducted

to provide data and develop test methods for evaluating water saving devices for water

closets. Criteria for performance and testing procedures for laboratory testing are recommended for evaluating two-step flush devices for installation in conventional

water closets.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) dual flush toilets; low flush toilets; water closets; water conservation.

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

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