Analysis of Pneumatic Pressure Vibration Affected by Connecting WCs and Discharge Load Types

• Main Authors: Kazuya Fujimura, Kyosuke Sakaue
• Format: Article
• Language: English
• Published: MDPI AG 2017-05-01
• Series: Water
• Subjects: drainage system; trap; induced siphonage; vibration reply phenomena
• Online Access: http://www.mdpi.com/2073-4441/9/6/382

In the design of a drainage system, allowable drainage flow quantity (drainage capability) is defined for each pipe diameter in order to prevent seal water from breaking. In Japan, SHASE-S 218 (Heating, Air-Conditioning, and Sanitary Standard) stipulates the evaluation standard for drainage capability. Regardless of the presence or absence of connection of the traps, there are two types of test criteria. One is that pressure in the pipe should fall within ±400 Pa, and the other is that the seal loss should be less than 25 mm. Nevertheless, recent studies revealed that the connecting of traps attenuates pneumatic pressure in pipes and causes a tendency of the power spectrum distribution to change. This phenomenon may be attributable to the fact that seal water vibration is a response phenomenon to pneumatic pressure vibration, and that they affect each other. In view of this, we conducted discharge experiments based on SHASE-S 218 with and without traps (including water-saving toilet bowl (hereinafter, referred to as “WC”) using a real size drainage experimental system to clarify how the connection of WC might influence pneumatic pressure. We revealed that as the number of toilets connected to the drainage system increases, the pneumatic pressure and seal water loss decrease.