Air Admitttance valve Durgo

Air admittance valves (also referred to as Durgo valves) are used to provided internal venting for soil and ventilating stacks - this can either be within rooms or the roof space. One great advantage of air admittance valves is that they remove the need for holes through the roof or external walls. They use also reduce the amount of pipework needed to fit an external, open soil or ventilating stack.

The air admittance valve incorporates a sealing diaphragm which under its own weight or slight spring pressure is normally held closed, thus sealing the foul air within the pipework - see diagram right. 

When an appliance discharges into the drain, a slight negative air pressure is produced in the drain pipework which lifts the sealing diaphragm and allows air to be drawn in - see right lower. This intake of air equalises the air pressure and the sealing diaphragm falls back sealing the valve. The inrush of air through the open valve prevents the foul air in the pipe from escaping into the room/roof space and prevents the water seals in traps along the pipework from being broken. 

An air admittance valve must be installed so that it is positioned above the highest flood level of the appliances fitted to the pipe - that is to say, where a washbasin is connected to the pipework, the air admittance valve must be higher than the overflow of that basin. This is to ensure the correct operation of the air admittance valve, otherwise there is a risk that the water seal in the basin's trap may be broken. 

The use of air admittance valves are governed by building regulations (Part H) and they cannot be used in all situation, these regulations should be checked before specifying the use of an air admittance valve - generally speaking, within a normal, two storey house with an existing vent pipe, there will be no problem; fitting within a taller building or a block of flats may be problematic. 

Air admittance valves are easy to fit, some incorporate seal rings which seal against the inside of the pipework, other valves just slip onto the top of the vertical pipe.
The two main constraints when fitting Air Admittance Valves are:

1. They can only be fitted to vertical pipework - turning the valve on its side will mean that the seal won't work.
2. They should only be fitted within a building to avoid the risk of them freezing during winter frosts. Most air admittance vales are supplied with a formed polystyrene moulding, which should be fitted to the valve top after installation in an unheated roof space to provide added protection from frost.

Problems can arise where air admittance valves are fitted to vent pipes which are not separately vented and which include water traps - this can lead to back pressure in the pipework when an appliance is discharged which will effect the appliance discharge - this will be especially noticeable when a toilet is flushed. 

Air admittance valves do not need any maintenance but can cause problems if they become faulty as they may allow sewer gas into the building.

A few years ago we had a durgo valve fitted in our family bathroom (built in next to the sink unit and boxed in) to free up the space taken by the original vent pipe.  Since then we have had the intermittent problem of a foul smell in the bathroom which is gradually occurring more and more.   Since my children left home this bathroom is not in daily use.  When the smell occurs (at least once a week) I have checked and it is not coming from the bath, bidet, sink or WC as far as I can tell.  If I flush the appliances it does not seem to make any difference. Does this sound like a faulty durgo valve or is there another likely cause?  Also the valve is below the basin waste height, being under the counter top.  Is this OK? Posted: Wed Nov 07, 2007 7:12 pm Post subject: durgo smell problem  By the nature of durgos ( automatic air admittance valves ), they should not be fitted as an alternative to natural ventilation, as they are not ventilation at all.   Unless faulty they don't smell.   If the spring goes they smell something rotten, and allow methane into the room. Not nice at all. As for the height they should be fitted, the manufacturers stipulate they should be fitted above flood level.   Some plumbers like to fit them one metre above FFL ( finished floor level ), but if the water is getting that high, its been coming out over the toilet for some while, so in theory they only need to be some short distance above the rim of the WC.    As just about every WC measures 16" ( except disabled suites , 18" ), 20" should be enough[/i]  Your problem with bathroom smell and the installation you describe is almost exactly the same as ours.   The main difference appears to be that we notice foul smell mainly first thing in the morning, not during the daytime.   I would be very interested to know what you have actually done to try to eliminate the smells and to what extent you have been successful.   My thoughts at the moment tend towards having the vent pipe directed horizontally through the wall (below worktop height so that it is still not visible from inside the bathroom) and then up the wall to terminate above eaves level.  I am still trying to get the original plumber/installer in to look at the problem and get his observations.

================================== 

通氣凡而

通氣管可裝在屋內，劃時代的污排水通氣凡而

http://www.beiming.com.tw/products/durgo/index_en.htm

Durgo 通氣凡而乃取代以前舊式之通氣管延伸至屋外大氣中，而可在屋內處理者，由瑞典開發之劃時代產品，使排水系統簡單化。經十幾年之實証，在瑞典、歐洲及日本使用者之評價甚高，並獲得世界二十餘國之專利。

圖一 舊式通氣凡而末端

圖二 新式通氣凡而末端

Durgo製品說明

A.構造及材質:(參閱圖三)

(1)上蓋 (2)封圈(Seal) (3)可動盤 (4)本體 (5)接頭
材質:凡而本體--- ----ABS(樹脂) 封圈(Seal)-------EPDM

圖三

B.機能:凡而之動作原理(參閱圖四)

1. 正常時(無負荷時)封圈(Seal)關閉，防止臭氣溢出。
2. 水時排水管內形成負壓，封圈因壓力差而升起，吸入排水所必要之空氣，保護衛生器具之存水封，並使排水圓滑順利。
3. 排水終了時，管內正壓發生，封圈關閉 防止臭氣溢出。
   圖四
   

名稱 Dim D H 附斷熱材時 D H AVLOPP DN50 50 84 98 120 120 AVLOPP DN75 75 118 107 155 133 AVLOPP DN90 90 140 121 180 143 AVLOPP DN110 110 140 125 180 147 AVLOPP DN100/88 114 170 115 210 145 AVLOPP DN125/89 140 140 150 180 158

----ABS(樹脂) 封圈(Seal)-------EPDM

圖三

B.機能:凡而之動作原理(參閱圖四)

1. 正常時(無負荷時)封圈(Seal)關閉，防止臭氣溢出。
2. 水時排水管內形成負壓，封圈因壓力差而升起，吸入排水所必要之空氣，保護衛生器具之存水封，並使排水圓滑順利。
3. 排水終了時，管內正壓發生，封圈關閉 防止臭氣溢出。
   圖四
   

吸气阀 http://www.durgo.se/ 现在人们不再需要为排水系统而在屋顶上开孔了。 开孔即昂贵又麻烦, 管子周围的密封也许会引起泄漏。 Durgo(多歌)吸气阀装于建筑物内易检查维护且温度不低于零点之处。 Durgo(多歌)吸气阀型号多，出厂允许安装高度为12层，可装于排水立管和通气管上。 请参阅我们的有关吸气阀的 产品手册 和产品 宣传片。

--> 北名實業有限公司　版權所有 © 2002 BEIMING Int'l Corp., All Rights Reserved
臺北市承德路三段九十九巷十號
TEL: 02-2592-7857 FAX: 02-2595-9722