do I need to include loss in a surge anticipator valve in TDH?

[QQstuff]

I have a dum question, CLA-VAL suggested me to use a 8inch surge anticipator valve for 4167 gpm, as they said the valve only opens when surge occurs, in this case do I need to inlude the loss across the surge anticipator valve, which is really high (30 psi at 4167 gpm)? It sounds like I dont need to included it as the surge anticipator valve only works when pump shuts down during a power failure. as the pump does not need work, it does not need to pump water at all, thank you.

 

[stanier]

You need to model your system for pump trip. The losses through the surge anticipation valve do need to be taken into account. Such a valve is connected to a branch of the main line and relieve the surge pressure before it occurs. If you dont know if this valve has reeduced the pressure how do you know if the return surge wave will be damaging or not. The surge anticipation valve can only relieve pressure by discharging fluid from the pipeline. The pipeline will have expanded under pressure. When the pump stops a volume of water has to be released. the loss through the surge anticipation valve determines the time to relive the pressure.

Beware that surge anticipation valves sound great in theory. Having modelled and commissioned these many times as a potential solution I can tell you that they are not the panacea the salesman would have you believe. In addition they are high maintenance. If you dont maintain them they dont work. Refer

http://www.pipingdesign.com.

There are a couple of papers there you should read on surge.

If ther salesman has done the surge analysis for you i would be doubly wary as to the results. There is a conflict of interest there.

Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng

http://www.waterhammer.bigblog.com.au

 

[bimr]

No, you do not need to include the pressure drop for the surge valve since the surge valve is discharging to atmosphere.

From you post, it sounds like you do not have much experience with surge analysis. You probably should have an experienced person review your work.

 

[QQstuff]

Thanks. Now it looks like I'd better use a pump control valve sinstead of a surge anticipator, as the latter does not provide check valve feature.