CIBW062 Symposium 2013

A study of 4 liter toilet with new flushing technology

Kojiro Watari (1), Masayuki Otsuka (2), Satoshi Kitamura (3)

1 [email protected] 2 [email protected] 3 [email protected] 1 Living Space Element Developing Office, Technology Research Department, LIXIL Corporation, Japan 2 Professor, College of Architecture and Environmental Design, Department of Architecture and Environmental Design, Kanto-Gakuin University, Japan 3 Innovative Development Promotion Office, Technology Research Department, LIXIL Corporation, Japan

Abstract

Some types of toilets with around 4 liter flushing water are available in the markets. Those toilets are equipped with variety of devices to eject wastes with small volume of water. However, we understand our customers have other needs besides water saving, and we have to make further efforts to meet these needs. For instance, our customers request for compact sized and quiet flush toilets. Tankless toilets are well accepted in terms of the size, but they are louder than toilets with a tank. Although toilets with a tank can be installed anywhere regardless of a level of water pressure, as an advantage, they are less popular due to the design and the size. This report introduces a toilet with a new technology to cope with these problems.

Keywords

4-liter toilet, pressurizes the flushing water, tankless toilet, drainage flow rate, drainage transportability

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1. Introduction

In recent years, water saving toilet technology has been advancing rapidly in Japan. About 20 years ago, generally the flushing volume of 13-liter was very common. In 2011, a 4 liter toilets was been launched. At present, there is even less than 4 liter toilets in the market. However, as a water saving technology progresses, there worries about flushing performance, drainage transportability and detergency of bowl. In Japan, a large floor space can’t be allocated for the toilet. Therefore, a lot of Japanese customers demand a small size and quiet toilet. In addition, they wish to wash the toilet bowl well because their awareness about cleanliness is high. Moreover, there is growing a demand for toilets whose performance does not get affected by the height of the installation floor because the number of cases of installation on the upper floors has been increasing since the market for apartment complex is getting bigger. Tankless toilets are smaller in size and more stylish than the conventional toilets with a tank. Since Japanese customers appreciate these features, more and more people have been buying them since 2001. On the other hand, people require the tankless toilets to have a higher level of flushing performance, quietness, and flexibility for installation to the site where water pressure is low. The new technology was developed in order to meet these requirements. This report introduces the new technology, and shows results from our study which evaluated its drainage characteristic and the drainage transportability.

2. Structure of 4 liter toilets

2.1 The new 4 liter toilet : The tankless toilet with electrical pressure device

This system, which is referred to as Type A, pressurizes the supplied water by using a electrical pump. It is similar in outer appearance to the conventional tankless toilets, and the water in the tank doesn’t have the potential energy as a gravity feed toilet. So, it was categorized as a tankless toilet. In terms of functionality, it is different from the tankless toilet in the past. Firstly, the noise is the same as the conventional gravity feed toilet because the jet nozzle was removed. Secondly, the total flow water can clean up the bowl surface. Finally, the system isn’t effected by the water supply pressure by using the pump pressure for the flush. Of course, the flushing water volume does not change, and the size is also almost the same. It is realized by high flow pump, water discharge balance and its operation timing.

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1) Flushing 2) Refilling water : bowl 3) Refilling water : tank

Figure 1 - The system of the new tankless toilet with electrical pressure device

Flushing progresses as follows: (Figure 1) 1) Water in the tank is flushed by using a pump. The flow rate is almost equal to the conventional gravity feed toilets. The total flow water cleans up the bowl surface. A siphonic effect produced by the flushing water ejects all of the waste from the bowl completely. Water supply is stopped at this time. 2) The bowl is refilled with water by using again the pump after ejects of the waste is completed. Water supply is still stopped still at this time. 3) After the flushing operation, the water supply valve is opened to refill water into the tank. Water supply needs to be stopped when it is refilled up to the given water level.

The flushing performance and the flushing water volume are stable in spite of changes in water supply pressure because water supply is stopped during the flushing operation.

2.2 Existing 4 liter toilets: The gravity feed and the tankless

We will briefly explain the structure of 4 liter toilets which was released in the past. Since we reported it at this symposium last year.

2.2.1 The tankless toilet with a non-electrical accumulator

This device pressurizes the supplied water by using a mechanical accumulator. This system reduces the flushing volume comparing to the conventional tankless toilets by combining and directly connecting the supplied water with pressurized water from the accumulator. In this report, the 4-Liter tankless toilet is referred to as type B and the conventional 5-Liter tankless toilet is as type C.

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Figure 2 - The system of the tankless toilet with accumulator

Flushing progresses as follows: (Figure 2) (1) Water is flushed, and washes the bowl. The spring of the accumulator stays contracted. (2) Jet water is discharged from the jet nozzle at the entrance of the trap way and causes a siphonic effect. Then the spring discharges water from the accumulator. So the tankless toilet can temporarily obtain a higher pressure level than the simply supplied water. (3) The bowl is refilled with water. After the flushing operation, the spring becomes is contracted by the water pressure again.

2.2.2 The gravity feed toilet with a non-electrical vacuum aspirator

This system, which is referred to as Type D, is similar in outer appearance to the conventional gravity feed toilet. The top of the trap way has a hole that is connected to the cylindrical chamber which is a part of the flush tank. When flushing the toilet, it produces a siphonic effect with the aspiration of air through the trap way during flushing.

Flushing progresses as follows: (Figure 3) (1) Water in the cistern begins to flow into the bowl. (2) Lowering the water level in the cylindrical chamber acts like a piston, and generates a negative pressure and a siphonic effect is produced. The siphonic effect ejects all of the wastes from the bowl completely. (3) Once the water reaches a certain level, the vacuum effect stops. (4) The cistern and bowl are refilled with water.

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(2)

(3) (4)

Figure 3 - The flushing sequence for the Gravity Feed Toilet with an aspirator

3 Summary of the methods of experimentation

In order to clarify that a new toilet has enough performance which is required in Japan, we measured the drainage characteristic and the drainage transportability. We also evaluated how the partial flush contributes to the transportability. The object of the experiments was type A. For comparison, we will quote the results of type B, C, D and E described in the literature in the past.

3.1 Measurement of the drainage flow rate

We confirmed the drainage flow rate of the new toilets by installing the measuring equipment shown in Figure 4. Pressure change of the inflow to the box was measured by a pressure transducer and converted into the flow rate change of drainage. This method is based upon SHASE-S220 (Society of Heating, Air-Conditioning and Sanitary Engineers of Japan), a standard that Japanese pluming systems are usually designed in accordance with.

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Test sample

Water tank

Figure 4 - Equipment to measure flow late of drainage

3.2 Measurement of the influence on trap water seals of other devices by a flushing toilet

In order to confirm how the new toilet flushing effects the trap water seals of the other devices, we conducted drainage experiments by using a simulation tower in Kanto-Gakuin University, as shown in Figure 5. The diameter of the vertical pipe was 100[mm], the main horizontal pipe was 125[mm] and the pipe inclination was 1/150. An overhead-venting pipe was installed on top of the vertical pipe. Two test samples were installed on the 7th and 8th floor in the tower. We measured the following two conditions after flushing the toilets. (1) Pressure on the horizontal fixture drain on each floor (2) Change in the trap water seals of other devices

We measured the pressure in the pipe with a semiconductor pressure sensor. Three types of traps; for watertight pans, lavatories and bathtubs were installed on the 6th floor. We especially paid attention to the water seal change of the pan trap because it is the most affected device by flushing toilet. These experiments were conducted in two flushing patterns. The first condition is flushing two toilets on the 7th and 8th floor. Second is flushing only on the 8th floor. We decided that flushing time-lag was 2 second. Pressure change in the pipe recorded maximum in each case of 1 and 2 second, then we selected longer one due to measurement accuracy.

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P Pressure sensor Vertical main pipe h Wave gauge 100A

JIS DT joint 100A×75A P

P Drainage load

P Drainage load

P h

P

P

P

Test Trap P h

Diameter convertor 100A×125A 90 deg bend pipe 125A×125A Horizontal main pipe 125A 1/150 Figure 5 –Picture and drawing of equipment with vertical

3.3 Measurement of the drainage transportability

As test media of transportation experiment, we used 6-ply of JIS P 4501 standard toilet paper (single type). Each ply is 1 meter's worth which was folded 4 times into a sheet of paper with a total length of 125[mm]. The paper was laid on the water surface in a stacked flat. After soaked in water for 15 seconds, drainage was performed. As shown in Figure 6, we have measured the distance between the core of the vertical pipe and the tail of the stagnant test media as the transportation distance. The interval of time between full flush and following partial flush was 700 seconds which is average interval of drainage equipment in housing by SHASE-S206.

Transport distance with 1st full flush The fixture drain Test media Vertical main pipe 100A 75A 1/100 Diameter convertor Test media Tale of the waste Transport distance with a partial flush after a full flush Transport distance The horizontal main pipe of the drainage stack system 図 2 汚物搬送性能の測定方 125A 1/150 法 Figure 6 - Method for measuring the transportation distance

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9000

straight 9m (system 1) 1000

17 bend in 18m (system 2)

Figure 7 - Equipment to measure the drainage transportability

The experimental equipment of the horizontal drainage pipe constructed from rigid PVC pipe which is 75 [mm] in diameters and 1/100 in gradient., the 1m pipes connected each other were placed straight up to 18m in length (system 1). And the pipes connected by 90 ° LL at intervals of 1m, were placed horizontally in a zigzag up to 18m in length (system 2) as shown in Figure 7. We evaluated the drainage transportability of single full flush and the effect of partial flush after full flush for transportability. The transport evaluation was repeated three times each, recording the average, maximum, minimum.

4 Results and consideration

4.1 Drainage flow rate

Table 1 – property of test sample Drainage Average flow Maximum Volume Division flow rate rate flow rate W[L] td[s] qd[L/s] qmax[L/s] Type A Full 4.1 1.2 2.1 2.1 (4L new tankless) Partial 3.4 1.1 1.9 1.9 Type B Full 5.1 2.6 1.2 1.9 (5L tankless) Partial 4.4 2.1 1.2 1.9 Type C Full 4.4 2.0 1.2 2.1 (4L tankless) Partial 3.5 1.4 1.3 2.0 Type D Full 4.3 1.6 1.5 2.1 (4L Siphonic GF) Partial 3.8 1.2 2.0 1.9 Type E Full 8.1 3.8 1.4 1.8 (Wash-down GF)

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Table 1 shows properties of the test samples. The average drainage flow rate (qd) of type A was slightly higher than the other toilets in both full flush and partial flush. However, in terms of maximum flow rate (qmax), type A was similar to type D. Drainage time (td) of type A was shorter than the other toilets. The reason is that the wash water maintained a large flow rate by the pump.

4.2 Trap water seal change of other devices

We clarified that the new toilet flushing less affects the trap water seal of the other devices on under floor than the conventional toilet. Due to the new toilet has smaller change of pressure in the pipe during flushing than the conventional one. Figure 8 shows maximum pressure Psmax and minimum pressure Psmin in the pipe about each sample. Psmin is the same as each sample in one toilet flushing condition as shown in Figure 8. In case of two toilet flushing condition, Psmin of type A is –260[Pa], that is smaller than type E. In addition, that is similar to type C and D.

Type A Type C Type D Type E ＊

9F 9F Flush Flush 8F 8F Flush 7F 7F

6F 6F r r

Floo 5F 5F Floo

4F 4F

3F 3F

2F 2F

1F 1F -400 -200 0 200 400 -600 -400 -200 0 200

Pressure in the pipe [Pa] Pressure in the pipe [Pa]

Figure 8 - Pressure distribution

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Figure 9 shows ⊿hmax, loss of the trap water seal of the pan trap after 5 times flushing without supplying water. ⊿hmax is sufficiently low level with either sample under one toilet flushing condition. However, in case of two toilets flushing, ⊿hmax of type E is 46[mm] and trap water seal of that momentarily breaks in first flushing. Additionally, it breaks completely in second flushing. On the other hand, ⊿hmax of type A is about 20[mm] also sufficiently low level. That is similar to type C and D.

Type A Type C Type D Type E ＊ ]

] 60 60 50 50

40 40 30 30 20 20

10 10 Loss [mm ofseal the water Loss [mm ofseal the water 0 0 012345 012345 Number of the flushing cycles Number of the flushing cycles

Figure 9 - Loss of pan trap water seal after flushing

4.3 Drainage transportability

In case of single full flush only, the relation between the transportation distance and the flush volume of each toilet is shown in Figure 10. We also showed the results of other toilets (type B, C, D, E) described in the literature. On the straight piping (system 1), despite the reduced amount of flush volume, their transportability were about to decline slightly. However, on the bend piping (system 2), the rate of decline in the transportability due to the decrease of flush water became higher. In the case of compared among same flush volume, type A was longer than the other toilets by both systems. Next, Figure 11 shows the distance with a partial flush after a full flush. We also showed the results of other toilets (type C, D) described in the literature. In all toilets, it was confirmed that a partial flush after a full flush encouraged the transportation distance. In addition, type A was longer than type B, D that is same flushing volume.

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Type A Type B Type C Type D Type E System1 ＊ System2

9 L = 0.43V+ 4.22 18 8 2 16

R = 0.28 m 7 14 6 12 5 10 4 8 6 3 4 2 2 1

Transportation distance [ distance Transportation 0 Transportation [m] distance

0 Full Full Full

4.0 4.5 5.0 5.5 6.0 6.5 Partial Partial Partial Partial Partial Partial 1st 2nd 3rd 1st 2nd 3rd 1st 2nd 3rd Flush volume V [L]

Figure10 -Distance with a full flush Figure11 –Distance with a partial flush after a full flush

5 Conclusions

We confirmed the following results about the new toilet with the new piece of technology. 1) The average flow rate and the effect on trap seals of other devices are comparable to other 4L toilets. 2) Average transportation distance of single full flush is longer than other 4L toilets. 3) A partial flush after a full flush enhances the transportation distance in the both drainage system.

6 References

(1) Japanese Standards Association, Toilet tissue papers JIS P 4501, 2006 (2) Society of Heating, Air-Conditioning and Sanitary Engineers of Japan, SHASE-S 220-2010, 2010 and 206-2009, 2009 (3) H.Kagami, M.Otsuka, H.Hoshina - Kanto Gakuin University, K.Hirai - INAX Corporation, Influence on Drainage Capacity of Super-Water Saving Closet Uses 5-liters, Summaries of Technical Papers of Annual Meeting Architectural Institute of Japan, 2010. (4) K.Hirai - LIXIL Corporation, M.Otsuka - Kanto Gakuin University, S.Kitamura- LIXIL Corporation, 4-Liter Water Closets With New Flushing Technologies, CIB W062, 2011. (5) S.Kitamura - LIXIL Corporation, M.Otsuka - Kanto Gakuin University, K.Hirai - LIXIL Corporation, A Study on Drainage Transportability of Dual Flush 4-Liter Toilets, CIB W062, 2012

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6 Presentation of Authors

Kojiro Watari is working at LIXIL Corp. He is a researcher in the research department development elemental technology laboratory. He is a member of AIJ (Architectural Institute of Japan)

Masayuki Otsuka is the Professor at College of Architecture and Environmental Design, Department of Architecture and Environmental Design, Kanto-Gakuin University, Dr. Eng. He is an academic director of SHASE (Society of Heating, Air-Conditioning and Sanitary Engineers of Japan) and a member of AIJ (Architectural Institute of Japan). His current research interests are the performances of plumbing systems, drainage systems design with drainage piping systems for SI（Support and Infill） housing and the performance evaluation of water saving plumbing systems.

Satoshi Kitamura is working at LIXIL Corp. He is a researcher in the research department development elemental technology laboratory. He is a member of SHASE（Society of Heating, Air-Conditioning and Sanitary Engineers of Japan）

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