A Study on the Evaluation of a Super Water-Saving Toilet in Regard to the Drainage Performance Thereof in the House Drain Section
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CIBW062 Symposium 2012 A Study on the Evaluation of a Super Water-Saving Toilet in Regard to the Drainage Performance thereof in the House Drain Section Naofumi Kobayashi (1), Masayuki Otsuka(2) 1. [email protected] 2. [email protected] 1. Graduate student, Graduate School of Engineering, Kanto-Gakuin Univ. 2. Department of Architecture College of Engineering, Kanto-Gakuin University, Dr. Eng, Japan Abstract Toilet efficiency in conjunction with water conservation has been promoted worldwide, but this unfortunately often diminishes the drainage performance in the large-diameter house drain section of drainage systems, causing waste materials, toilet paper, etc. to block the house drain, as reported at the International Symposium of CIB W062. In Japan, 6-litre flush toilets which were mainstream a few years ago have been gradually taken over by super water-saving toilets which use much less water and are becoming more available on the market. This paper examines, through experiments, how the drainage performance of the house drain is affected by employing different types of super water-saving toilets, including those using less than 6 liters of water, in consideration of various factors, such as the type of waste material (substitute), the toilet drain height, and the condition of drainage flow. Keywords Super water-saving toilets, House Drain, 1 Background of the study Toilet water conservation has been promoted worldwide, and 4.8-litre toilets are available in the West Coast of America. However, toilets using less water can diminish the carrying performance of the house drain of drainage systems, as pointed out at the International Symposium of CIB W062. Fig. 1 shows the trend of toilet water conservation in Japan in relation to standards and specifications. In Japan, 6-litre toilets have been used since 1999, and in 2011, 4-litre toilets became available in the market. 277 CIBW062 Symposium 2012 At present, even more efficient, 3.8-liter toilets are commercially available. Water-saving toilets in Japan are currently classified into type I and type II, depending on the type of flushing system and the amount of water used for flushing (see Table 1), in accordance with Japan Industrial Standards (JIS). At the International Symposium of CIB W062, it was reported that in Taiwan, the application of water-saving toilets diminished the carrying performance of the house drain of drainage systems1)2). Subsequently, this report evaluates the carrying performance of the house drain when waste substitutes are drained from different heights through a drainage stack system which is equipped with a 4-litre super water-saving toilet. Furthermore, based on the assumption that the downward flow of drainage water and waste in the drainage stack affects the carrying performance of the house drain, this report clarifies the relationship between the carrying performance of the house drain and the drainage characteristics at the base of the drainage stack. 13L 10L flush water flush Transitionof ofamount the 8L 6L 5L 4.8L 4L 3.8L 1990～ 2000～ 2010～ BL Standards Methods of Testing Performance of Apr. 1999 Jul. 2006 Jan. 2011 Quality Housing Components Waste substitutes Waste substitutes Waste substitutes BLT WC:2010 Lay flat paper 3.6m PVA sponge 2 Roll of paper 6m (The Center for Better Living) Balled-up paper 4 JIS A 5207 Sanitary wares Jan. 2011 (Japan Industrial Standards) Formulation of water-saving and specifications and Related standards Related type Ⅰand type Ⅱ Other Overseas regulations 1992～ 2011 Regulations on 6-litre flush Regulations on 4.8-litre flush toilets toilets （Some parts of the US） California Environmental Protection Energy Policy Act(USA) Agency regulations Fig. 1 Trend of toilet water conservation and related standards and specifications Table 1 JIS classification of water-saving toilets Classification Cistern Flush valve Type I 8.5[L] or less 8.6[L] or less Type II 6.5[L] or less 8.5[L] or less*) *)Type II/flush valve: limited to specific-type toilets with a flush valve 2 Objective of the study Using an experimental tower which simulates a typical drainage system for high-rise buildings, this study discusses the following points about the carrying performance of the house drain: (1) Clarify the relationship between the toilet drain height and the distance waste substitutes are transported in the house drain. (2) Examine the toilet drain height and the variation of the drainage characteristics measured in the base part of the drainage stack 278 CIBW062 Symposium 2012 3 Outline of the experiment (1) Experimental systems (A) House drain carrying performance experiment This experiment employs a high-rise simulation tower of Kanto Gakuin University, which has nine storeys and a height of 25m. Fig. 2(a) shows the stack system used for this experiment. The stack system is of a vent type and comprises a drainage stack with a diameter of 100A (with JIS-DT fittings attached thereto), and horizontal fixture branches with a diameter of 75A (pitch 1/100). The diameter of the house drain is 125A (pitch 1/150), and the length thereof is 18m with reference to the previous report2) presented at CIBW62 in 2011. In (a) the house drain carrying performance experiment, a super water-saving, 4-litre toilet is used, and a drainage load is applied from the 1st to 8th floors respectively. Incidentally, there are two types of drainage loading: a large amount of flush water for draining solids (full flush) and a small amount of flush water for draining urine (partial flush). As waste substitutes are drained from each floor, the distance they are transported in the house drain is measured. (B) Stack drainage characteristics experiment This experiment uses a stack comprising a large inlet installed at the base of the stack, and the characteristics of a downward flow in the stack are measured. Fig. 2(b) shows the stack system used for this experiment. In (b) the stack drainage characteristics experiment is implemented from the 1st, 3rd, 6th and 9th floors which provide typical drainage loading conditions. Bellmouth Vent section: bellmouth Horizontal branch: diameter 75A pitch 1/100 Stack: diameter 100A House drain: diameter 125A pitch 1/150 House drain connection points (flanges and sockets): 1.5, 3, 4, 6, 7, 9, 13, Power and 17m from the amplifier stack Low-pass filter Increaser A/D converter 100×125 PC (a) House drain carrying (b) Stack drainage characteristics performance experiment experiment Fig. 2 Experimental stack systems 279 CIBW062 Symposium 2012 (2) Discharge Characteristics of Toilets Fig. 3 shows curves representing the discharge characteristics of the toilet used in the experiments. The curves are of discharge volumes, discharge flow rates, etc. which were recorded when the full flush and the partial flush were used. Meanwhile, Table 1 lists the values of the discharge characteristics of the toilet. Incidentally, a 4[L] toilet was used in the experiments, and the discharge characteristics thereof were measured in accordance with SHASE-S 220-2010, “Testing Method of Discharge Characteristics for Plumbing Fixtures”. The average discharge flow rate, qd, is one of the indices representing the discharge characteristics of plumbing fixtures, and a qd value is obtained by measuring a discharge flow rate while 20-80% of flush water is discharged from a toilet and dividing the discharge flow rate by the discharge time. Table 1 also lists the discharge characteristics of a 6-litre water-saving toilet for comparison. Table 2 indicates that although the 4-litre toilet used in the experiments uses less flush water, the average discharge flow rate, qd, and instantaneous maximum discharge flow rate thereof are greater than those of the 6-litre toilet. This suggests that a high discharge flow rate compensates for a small amount of flush water so that the discharge performance of a toilet does not have to be compromised. 2.5 10 2.5 10 Discharge flow rate ] qmax ] Discharge volume L L [ [ [L/s] [L/s] 2.0 8 2.0 8 qmax td 1.5 6 1.5 6 1.0 80% 4 1.0 4 0.5 0.6W 2 0.5 2 20% Discharge volume Discharge Discharge volume Discharge Discharge flow rate flow Discharge Discharge flow rate flow Discharge 0.0 0 0.0 0 0 5 10 15 20 0 5 10 15 20 Measurement time [sec] Measurement time [sec] (1) Full flush (2) Partial flush Fig. 3 Discharge flow rate curves and discharge volume curves Table 2 Discharge characteristic values Avg. Instantaneous Avg. discharge flow rate Discharge Discharge discharge max. discharge with the drain pipe flow rate time flow rate flow rate connected Type of flush W[L] td[s] qd[L/s] qmax[L/s] qd'[L/s] Full flush 4.2 1.2 2.23 2.39 2.01 Partial flush 3.7 1.2 1.88 1.91 - 6L(Full flush) 6.0 1.9 1.93 2.11 - * The length of the horizontal branch with the drain pipe connected: 1m 280 CIBW062 Symposium 2012 (3) Waste substitutes for the experiments Table 3 and Fig. 4 show the waste substitutes used in the house drain carrying performance experiment. Waste substitute D is a 1m-long piece of paper (1 ply) which is folded into six layers, and waste substitute D’ is a 1m-long piece of paper (2 ply) which is also folded into six layers. Furthermore, new waste substitute BL is a 0.9m-long piece of paper (1 ply) which is folded into four layers, and this is in accordance with a BL (Better Living) standard, “Methods of Testing Performance of Quality Housing Components” which was formulated in 2011 by the Center of Better Living. In addition, in order to compare with the outcome obtained from the study in Taiwan, two pieces of PVA sponge were also used in the experiments for reference.