Air Bleed Valve at Pressure Gage - Required?

[Dan1978]

Hello
Hope this is the right forum for this question.

I am installing an inline sediment filter on a domestic water piping system. We want to install a differential pressure gage mounted above the filter to determine when the filter needs to be changed. The small 1/8” dia. pipes feeding the gauge will be tee’d off the main line from the top. Here’s a link to the pressure gage we’re using;

http://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gages/SeriesPFG2#features

Do I need to install air bleed valves at the inlets to the gage? My thought is it shouldn’t really matter what’s applying pressure to the gage itself, whether that be the fluid directly, or what will likely be the case, trapped air in the piping. The air and water have to be at the same pressure so as long as something is exerting the force.

I would like to avoid installing air bleed valves as there is limited space. Would really appreciate any thoughts or if someone has had a similar experience with a similar setup.

Thanks,
Dan Sheppard

 

[LittleInch]

If the lines to the DP guage are equal and short and you're not measuring in mbar, then you don't need an air bleed IMHO.

Probably better off in the plumbing forum TBH, but its ok here.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Dan1978]

Thanks LittleInch.

The pressure differential shouldn’t be more than 10-15 PSI. With the incoming pressure at around 50-60 PSI.

Am planning to keep the branch lines of equal length and short as possible. I figure as long as both lines are the same length and we’re measuring differential pressure it shouldn’t really matter anyway as the effect on both sides of the gage is equal.

I might post this thread in the plumbing forum as you suggest.

Thanks again.
Dan

 

[LittleInch]

The plumbing forum is rather dead compared to this one so I wouldn't bother, but if it's deep plumbing issue you want then try it first.

So long as you keep the possible mis match on head down to 1psi (2.3 ft) i.e. if one pipe is full and the other empty then you should be good to go for this usage. Its relative height from tapping point to guage that is important not length as there is no flow. So long as you try to get a gradual rise from your pipe to the guage you're good. Don't introduce dips or high point loops.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[PEDARRIN2]

The plumbing forum may be little used, but I would not think it is dead.

Maybe we are all zombies and nobody told us.

Putting pressure gauge(s) in line with filters is common to determine the need for changing/cleaning the filter elements.

The unit you are using looks a bit pricy. Typically I have seen two simple pressure gauges mounted upstream and downstream. The filter manufacturer should give you what the preferred pressure differential should be for replacing/cleaning the filter.

 

[LittleInch]

14 threads in one year and 12 of those in the first half of the year?

I did say "rather dead" and not rigor mortis....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Dan1978]

Lol thanks guys for the tips and spirited discussion. It is a smaller scale application and not a true pipeline but hey I figure you guys would know best.

Thanks again!