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 105 CIBW062 Symposium 2013 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. 106 CIBW062 Symposium 2013 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. 107 CIBW062 Symposium 2013 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. 108 CIBW062 Symposium 2013 (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. 109 CIBW062 Symposium 2013 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.