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4-Litre Water Closets with New Flushing Technology

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4-Litre Water Closets with New Flushing Technology Keisuke Hirai, Masayuki Otsuka and Satoshi Kitamura The following is a paper presented at 36th international Symposium of CIB W062 on Water Supply and
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4-Litre Water Closets with New Flushing Technology Keisuke Hirai, Masayuki Otsuka and Satoshi Kitamura The following is a paper presented at 36th international Symposium of CIB W062 on Water Supply and Drainage for Buildings. CIB, established with the support of United Nations, is world s foremost platform for international cooperation and information exchange in the area of building and construction research and innovation. Abstract The toilet would decrease the flushing volume without sacrificing the flushing performance required to eject excrement completely upon flushing. This report introduces 2 new pieces of technology for the gravity feed toilet and the tankless toilet. Due to their structural difference, they use various pieces of technology to solve the same issues. certification authority concerning quality performance, made 6-litre toilets the standard in JIS (Japanese Industrial Standard) also made 6-litre toilets the standard in addition to 8- litres toilet in According to our research, 4 litre toilets with new technology ensure the same performance or more than a conventional one on the point of flushing and ensure the same drainage performance. Keyword 4-litre toilet, Gravity Feed toilet, Tankless toilet, Vacuum aspiration drainage system, Non-electrical accumulator, flow rate of drainage, flushing performance 1 Introduction In recent years, water saving toilet technology has been progressing rapidly in Japan. Taking a look back on the history of water saving toilets in Japan, most toilets flushed 13 litres. This was about 20 years ago. The concern over the amount of wasted water of the toilet has been rising since 1990s. At that time 10-litre toilets had been becoming more popular, and in litre toilets were launched. Additionally, the first 6-litre toilets were starting to be introduced by the public housing organization in Due to their increasing popularity the progress of 6-litre toilets has been moving quickly since The standard of the toilet has changed along with the progress. BL (Better Living), which is the Figure 1 - History of water saving toilet in Japan If we consider the mechanisms of the common toilet, there are 2 main types of structure used for flushing. One of them is the Gravity Feed Toilet which is traditional and the world s most popular system. This toilet is equipped with a cistern which has about the same capacity as the flushing volume. The power of the flushing water is generated by the height of the water level. The other is the Tankless Toilet which is equipped with a small flush valve that is directly connected to the water supply line; flushing power is the same as the conventional toilet. Tankless Toilets are smaller and more stylish than the traditional toilets with a cistern. Since Japanese people appreciate these features, more and more people have been buying them since This report introduces and investigates 2 new piece of technology to further decrease the flushing volume down to 4 litres without sacrificing flushing performance in the 2 types of toilets. This report also shows and details the experiments used to evaluate them. JUNE 2 Structure of the new toilets INDIAN PLUMBING TODAY 2.1 Non-electrical vacuum aspirator for the Gravity Feed Toilet This system is similar in outer appearance to the conventional Gravity Feed toilet named type A. However, it has a special component in the flush tank. Figure 2 shows structure and flushing sequence diagrams of the toilet. This toilet has a common formed bowl and a cistern. However, they are not the same as in a conventional one because the top of the trap way has a hole that is connected to the cylindrical chamber which is a part of the flush tank. The cylindrical chamber is fixed in the middle of the flush tank. The top of the chamber is connected to the trap way with a check valve. The bottom of the chamber opens into the flush tank. When flushing the toilet, it produces a siphonic effect which vacuums air through the trap way during flushing. Flushing progresses as follows: 1) The flapper valve opens causing the water level in the cistern (also in the cylindrical chamber), to fall and the water level in the bowl to rise. This system is advanced because it works without an electrical power supply. This technology is using an electrically controlled drive unit (developed in 2008). This system reduces the flushing volume when compared to a conventional one, because the vacuum aspiration helps produce a siphonic effect more efficiently than only supplying water into the trap. 2.2 Application of a non-electrical accumulator for the Tankless Toilet This is the application of the existing technology which was developed in This device pressurizes the supply water using a mechanical accumulator. It was developed with the aim of keeping the flushing performance sufficient even at lower pressures. The conventional tankless toilet has a bowl and two small flush valves instead of one cistern. One of the valves is connected to a nozzle, which is called the Jet Nozzle, and is fixed at the bottom of the bowl directed into the trap way. The other is joined to another nozzle, which is called the Spiral Flow Nozzle, and is set at the top left side of the bowl. 2) The water level falls in the cylindrical chamber, which operates like a piston and sucks air into the trap way. Negative pressure is generated and a siphonic effect is produced. The siphonic effect ejects all of the waste from the bowl completely. 3) Once the water reaches a certain level, the vacuum effect stops. When the flushing is finished the flapper valve closes by itself. 4) The cistern and the bowl are then refilled with water. Figure 3 - The system of the tankless toilet with accumulator Figure 3 shows sequence diagrams of this device. This flushing system consists of three operations. (1) The spiral flow nozzle shoots flushing water into the bowl causing a vortex to occur which washes the bowl thoroughly. (2) Jet water is discharged from the Jet nozzle at the entrance of the trap way and causes a siphonic effect. (3) The bowl is refilled with water. Figure 2 - The flushing sequence for the gravity feed toilet with an aspirator The accumulator consists of a steel case, a spring, and a diaphragm. The device accumulates static pressure when the system is inactive, and discharges the pressurized water while flushing. JUNE This device proceeds as follows: INDIAN PLUMBING TODAY (1) The accumulator spring stays contracted before flushing because the restitution of the spring is less than the compressive force of the water pressure. (2) The expanding force of the spring enlarges beyond the compressing force due to the reducing water pressure. Then the spring discharges the water from the accumulator. Thus, the tankless toilet can temporarily obtain a higher pressure level than the simply supplied water. (3) After the flushing operation, the spring is contracted by the water pressure again. The 4-litre tankless toilet includes the nonelectrical accumulator as standard equipment. This system reduces the flushing volume when compared to a conventional toilet by combining a smaller quantity of directly connected water with pressurized water from the accumulator. vertical pipes. The subjects of the experiments were type A, B, B and type C, which is traditional 8- Litre gravity feed flushing toilet. 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. Water pressure was measured by using a pressure gauge, water pressure in the pipe was measured by a pressure transducer and the flow rate was measured by an electromagnetic pulse flowmeter every 0.01 seconds. Pressure change of the inflow to the drainage tank with baffle plate was measured by a pressure transducer and converted into the change of drainage flow rate. This method is based upon SHASE-S (Society of Heating, Air-Conditioning and Sanitary Engineers of Japan), standards. This organization typically sets the standards for design of plumbing systems in Japan. 3.2 Measurement of flushing performance In this report, 4-Litre tankless toilet is named type B. The conventional 5-Litre tankless toilet is named type B. 3 Summary of the methods of experimentation In order to ensure that the new toilets have sufficient flushing performance (which is required in Japan), we measured both the drainage flow rate and the flushing performance. We also tried to evaluate the effect of flushing on the trap water seals of other appliances in an apartment by using Figure 5 - Plastic balls provided by JIS Figure 6 - Papers laid in a double cross We confirmed number of plastic balls (19 mm in diameter and specific gravity of 0.9, provided by JIS) that new toilets could eject. These plastic balls are shown in Figure 5. JIS defines the criteria for assessment. JIS standards require a toilet should eject the plastic balls more than 85% in one flush. Additionally, we conducted our own experiment in order to clarify by measurement the flushing performance. In this experiment, the total length of JIS P 4501 standard paper the toilet could discharge, was measured. A 1 m length of toilet paper was folded in 6 layers, so that the total length of each section was 170 mm. The paper was laid on the water surface in a double cross formation, as shown in Figure 6. If the toilet paper was completely discharged from the toilet within a certain time, this was judged to be passing performance. We recorded the maximum discharged length. The dynamic pressure of the toilet was fixed at its possible setting that can be used; that is 0.05 MPa. 3.3 Measurement of the influence on trap water seals of other devices by a flushing toilet Figure 4 - Equipment to measure flow rate of drainage In order to confirm how the new toilets flushing effects the trap water seals of the other devices, JUNE we conducted drainage experiments by using a simulation tower in Kanto-Gakuin University, as shown in Figure 7-8. The diameter of the vertical main pipe was 100 mm, that of a main horizontal pipe was 125 mm and the pipe inclination was 1/ 150. An overhead-venting pipe was installed on top of the vertical main 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 drainage line on each floor (2) Change of trap water seals of other devices Figure 7 - View showing a frame format of equipment with vertical pipe JUNE We measured the pressure in the pipe with a semiconductor pressure sensor. Three types of traps; for watertight pans, lavatories and bathtubs; shown in Figure 9 were installed on the 1st, the 4th and right under floor where the toilet was installed. 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. 4 Results and consideration 4.1 Drainage flow rate Average drainage flow rate qd of the new toilets were slightly higher than the conventional toilet Drainage time were fairly shorter than the conventional toilet due to the reduced flushing volume. Figure 10 shows variation in drainage flow rate Qw and discharged volume W of test samples and table 1 shows their properties. The structure of type B and B is almost the same. Therefore, we didn t conduct experiences 3.1 and 3.3 about type B. Figure 10 - Variation diagram of the drainage flow rate and the flushing volume Table 1 - Property of test samples Volume Drainage Average flow Maximum W [L] Time rateqd flow rate td [s] [L/s] qmax [L/s] Type A (4-Litre new GF) Type B (Conventional tankless) Type C (Traditional GF) Flushing performance Figure 8 - Picture of equipment with vertical pipe Flushing performance of the new toilets is the same performance or better than the conventional toilet in small amounts of flushing volume. Table 2 shows flushing performance of test samples. (1)Trap for lavatory (2) Pan Trap Figure 9 - Picture of the traps (3) Trap for bathtub JUNE Table 2 - Flushing performance Dynamic pressure Ratio of ejected Distance of Flushing [MPa] plastic balls [%] ejected paper [m] volume[l] Type A (4-Liter New G.F.) Type B (4-Liter New tankless) Type B (Conventional tankless) Type C (Traditional G.F.) 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. We decided that flushing time-lag was 2 seconds. Pressure change in the pipe recorded maximum in each case of 1 and 2 second as shown in Figure Figure 11 - Time-lag for flushing 2 toilets 11, then we selected longer one due to measurement accuracy. Figure 12 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 12. In case of two toilet flushing condition, Psmin of type C is 560 Pa. On the other hand, that of new toilet is smaller than C. That of type A is 240 Pa. Figure 13 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 C 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 16 mm also sufficiently low level. Figure 12 - Pressure distribution JUNE Figure 13 - Loss of pan trap water seal after flushing 5 Conclusions We confirmed the following results about the new toilets with new technology. 1) Average flow rate of the new toilet is limited higher than the conventional toilet. 2) They have higher flushing performance than the conventional toilet. 3) They have smaller effect on trap water seal of other devices than the conventional toilet. The toilet will decrease the flushing volume without sacrificing the needed flushing performance in Japan. However, in other countries, the nature of the issue is the same in point of the toilet is required to eject waste completely while using as small a flushing volume as possible. The technology this report introduces are innovations of existing technology to solve the issue, therefore we expect that any toilets using this technology will be able to solve the same issue. 6 References (1) Japanese Standards Association, Sanitary wares JIS A 5207, 2010 (2) Japanese Standards Association, Toilet tissue papers JIS P 4501, 2006 (3) Center for Better Living, BLS WC2:2005, 2005 (4) Society of Heating, Air-Conditioning and Sanitary Engineers of Japan, SHASE-S , 2010 (5) K.Hirai, A.Yamamichi- INAX Corporation, M.Otsuka, H.Hoshina Kanto Gakuin University, Experimental study on drainage performance for Ultra low flow water closet with a vacuumaspiration drainage mechanism, (6) H.Kagami, M.Otsuka, H.Hoshina - Kanto Gakuin University, K.Hirai - INAX Corporation, Influence on Drainage Capacity of Super-Water Saving Closet Uses 5-litres, Summaries of Technical Papers of Annual Meeting Architectural Institute of Japan, (7) Yuji Nakayama - INAX Corporation, Masayuki Otsuka, Hideaki Hoshina - Kanto Gakuin University, Keisuke Hirai - INAX Corporation, New flushing technology of tankless toilet, CIB W062, 2010 IPT Keisuke Hirai is working at LIXIL Corp. He is an engineer in the product development department sanitary fixtures division. He is in charge of developing tankless toilets. He is a member of SHASE (Society of Heating, Air-Conditioning and Sanitary Engineers of Japan). He can be contacted at Masayuki Otsuka is the Professor at Department of Architecture, Kanto- Gakuin University. He is a member of AIJ (Architectural Institute of Japan) and SHASE (Society of Heating, Air- Conditioning and Sanitary Engineers of Japan). His current research interests are the performances of plumbing systems, drainage systems design with drainage piping systems for SIÿSupport and Infill housing and the performance evaluation of water saving plumbing systems. He can be contacted at Satoshi Kitamura is working at LIXIL Corp. He is a researcher in the general research institute of technology. He is a member of SHASEÿSociety of Heating, Air-Conditioning and Sanitary Engineers of Japan. He can be contacted at JUNE
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