Air release valve on sewage force main

[viktom]

I am looking for an advise from you all on the provision of air release valve on sewage main.

We are designing sewage force mains, the diameters of which are not going to be more than 200 DN and lengths not more than 1500 m . Whether the provision of air release valve is mandatory? or any guideline which dictates that?

 

[cvg]

this is basic pipeline hydraulics - if you get air trapped in the line, your capacity is reduced causing all kinds of problems. your design needs to either prevent air from accumulating or provide ways to release it.

 

[civilperson]

Constant slope lines do not need air release valves. Lines that run more than 90% of the time probably do not need release valves. Judgement is used in other cases. Smaller diameter lines work longer, needing less air purging.

 

[stanier]

Go to

http://www.ventomat.com.

Look at the model RGx. Also request their latest software on sizing and positioning.

 

[bimr]

Maybe this will help:

The Water Pollution Control Federation Manual of Practice No. FD-4 "Design of Wastewater and Stormwater Pumping Stations" states "A minimum velocity of 1.2 m/s (4 ft/sec) is required in the pipeline to shear the bubble and keep it moving downgrade." So if your pipeline velocity is capable of pushing air out of the line.

http://www.eng-tips.com/viewthread.cfm?qid=202513

I would add that for sewage force mains, it is generally recommended to have manual air release blowoffs than automatic ones. The reason is that the blowoffs may stick open when the debris in the sewer fouls the valves.

Air release valves are more useful when the forcemain traverses hills and valleys than on flat terrain.

Some regulatory agencies call for the devices, others do not. Check where you project is located.