PRV

[VTcivil99]

Civil engineer here modeling in WaterCAD. I have a 510 Zone HGL system interfacing with a 600 HGL Zone system. I currently have a PRV to separate the systems. Line size is 16". In most cases the systems operate independently and there is no flow across PRV. However if I run a fireflow test in the 600 Zone side, the pressures dip so much in the 600 Zone that some flow (350gpm) is flowing from the 510 to the 600 zone through the PRV to supplement the flow. This is what I want, but I'm not sure what physical valve setup this really is? The in the watermodel, the PRV is selected and the HGL to maintain is at 510 as in the PRV is ensuring the 600 Zone is at least 510 HGL that would be supplimented by the 510 zone below if needed. Perhaps there is a better way to accomplish this? This is an interim condition on the 600zone. Ultimately they will be an isolation valve here likely.

So long story short, looking to see how I can phsically specify what to use here. I need the lower 510 zone to supplement the 600 zone to reach my needed fire flow.

Thanks for you input.

 

[itascot]

when you refer to PRV do you mean SRV, PSV ?
Ciao,

 

[vpl]

Don't you love TLAs?

Patricia Lougheed

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[VTcivil99]

itascot: I'm not familiar with SRV? PSV is most likely what I want/mean. What I'm hoping is someone can read what I'm trying to accomplish and tell more more or less the physical device that matches up with my WaterCAD model's behavior. As in, the valve in essence isolates the 600 zone from the 510 Zone all the time, but in a fire event in the 600 Zone, the 510 suppliments the fire flow by the valve opening. So basically the 600 Zone HGL dips quite a bit to allow that to happen. In WaterCAD the device i'm modeling is a PRV or Pressure Reducing Valve.

vpl: I'm not sure what you mean by TLA's?

 

[DRWeig]

VTcivil99, you're getting some good-natured ribbing for using acronyms. We don't know what they mean for sure. Remember, your post is read around the world -- not just in your office where everyone knows what PRV, HGL, and all that other stuff is.

Please spell out acronyms at least once before using 'em, and it would help if you gave us a diagram to study. Then you'll probably get some good answers.

Good on ya,

Goober Dave

 

[JohnGP]

VTcivil99,
To me it's more a Pressure Regulating Valve (PRV) that you need. You can get self regulating types that will act in accordance with what is sensed in the downstream pressure, which seems to be your situation. If set to regulate downstream pressure to 510 (ft head?) then the valve would be closed while the downstream pressure was above that value. But if the pressure in the 600 zone fell below that, then the valve would begin to open to try and adjust it back.

Just on the TLAs (Three Letter Acronyms), as noted above there can unfortunately be more than one meaning - a PSV is not what you need (Pressure Safety Valve), but PRV is also used to mean Pressure Relief Valve.

Cheers,
John

 

[hsbcn]

It seems like you need a Presure Regulating Valve, but that's a reference to the valve function, which can be covered by different valve types. What pressure/temperature range are we looking at?

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[VTcivil99]

This is for domestic cold water.

 

[VTcivil99]

Okay, thanks for all the replies.

510 and 600 are referring to the ft in head, yes.

So as JohnGP says, that's the functionality I'm looking for. Basically the 510 ft of average head zone can provide some water to the 610 average head zone during a fire flow event in the 610 zone when the 610 dips below a setpoint of the valve which I would set for about 510 feet of head.

In the case of a 1,750 GPM fire flow event in the 600 zone, the current model in WaterCAD is showing the "valve" allowing 350 GPM through it from the 510 zone to the 600 zone and fire coverage is achieved. What confuses me the most is the WaterCAD model "works" when I set that vavle type to a PRV type (and I thought that was Pressure Reducing, but perhaps the model thinks it's pressure regulating.

 

[VTcivil99]

Just noticed I didn't fully respond to hsbcn. The pressure we are dealing with is domestic water distribution, so between 20psi and 120 psi depending on elevation.

 

[VTcivil99]

Am I overthinking this or is it simply a check valve? Water only flows from the lower 510 hgl zone to the higher 600 hgl zone when the 600 hgl zone drops pressure significantly during a fire flow event?

 

[VTcivil99]

anyone else want to chime in here?