Pressure relief vave blowing off air

[Afterimage]

Hi,I've revived my old Airmaster compressor with a new pressure switch and new gauges,and set the pressure switch to 150psi,which is the Max Working Pressure.

The problem is that the pressure relief valve starts to release air at just over 140psi - have I set my pressure too high,or is the relief valve faulty?

 

[gordon stephenson]

Sounds like your pressure relief valve is working fine, reset pressure switch to slightly below 140psi

 

[dannyp]

if max working presure is 150 the compressor is probaly have a normal operating pressure of 125 psi.

the relife valve is soposed to vent before the maximum working pressure of the vessel is exceeded as they arn't exactly presise things ony way to ensure they do is have one thats going to vent before max safe WP

 

[brightspark]

its a twin stage pump so will probably pump to 150psi and cut out at that . the blow of valve should be slightly higher but blowing of at 145 psi would be airing on the safe side and leave as such it will hardly make much diffrence. chances are the spring in blow of valve will be slightly weakened after years of compression

 

[rtbcomp]

The gauge may be faulty. Normally you choose a relief valve set to 1 bar over the SWP. The tank would be tested to 2 or 3 times the SWP.

SWP is the pressure it's safe to work at (!) so the safety valve shouldn't be lower than that.

As BS says, you can err on the safe side, reduce the cut-out pressure, the cubic feet per min (cfm) won't be affected.

 

[dannyp]

was made to have blowoff valve below working pressure ,

can i rip that on off and put a proper one back on

 

[Afterimage]

When it reached it's max pressure of 150psi indicated on the main gauge,that was also the maximum available at the regulator on that gauge too.

Both gauges are new,and I guess that if one or both were faulty they'd show different readings.

I'll follow the advice given and reduce the cut out pressure to just before the safety valve starts to bleed air.
This makes a lot of sense and has the bonus benefit of not costing more money.

 

[Mr shiney]

I have a safety valve on my vertical receiver tank that started to blow off before the compressor tripped. If you take the valve apart you will find a seat I that will have become contaminated and grooved. Clean the valve and turn the seat over and screw it down until it does not blow off anymore.

 

[brightspark]

I have a safety valve on my vertical receiver tank that started to blow off before the compressor tripped. If you take the valve apart you will find a seat I that will have become contaminated and grooved. Clean the valve and turn the seat over and screw it down until it does not blow off anymore.

but dont forget to reset it at correct pressure that is the general idea its no bl;;//dy good if it dont blow off some of them are just a spring and a ball bearing

 

[Afterimage]

but dont forget to reset it at correct pressure that is the general idea its no bl;;//dy good if it dont blow off some of them are just a spring and a ball bearing

My max safe working pressure being 150psi,I imagine the compressor being perfectly happy at that pressure - what psi would the safety valve actually be expected to start releasing air at if I were to have a fiddle with it?

 

[brightspark]

My max safe working pressure being 150psi,I imagine the compressor being perfectly happy at that pressure - what psi would the safety valve actually be expected to start releasing air at if I were to have a fiddle with it?

pump the tank up to your required pressure and slowly adjust the safety valve till it just starts to blows off then adjust it back up till it stops blowing and tighten it a fraction further and lock it

 

[Mr shiney]

The safety valve is there to protect the pressure vessel. So as long as it goes off a bit after the max pressure of the compressor its fine.

I pressure tested my receivers a couple of weeks ago and the pressure tests is 26bar. They get pumped to that (with water) and if they don't split the pass. I set my PRV at 12 bar.

Before anyone jumps on me pressure testing stuff I am a Uk HSE approved SCUBA testing testing station and have the facilities to test any pressure vessel up to 400bar.

 

[brightspark]

The safety valve is there to protect the pressure vessel. So as long as it goes off a bit after the max pressure of the compressor its fine.

I pressure tested my receivers a couple of weeks ago and the pressure tests is 26bar. They get pumped to that (with water) and if they don't split the pass. I set my PRV at 12 bar.

Before anyone jumps on me pressure testing stuff I am a Uk HSE approved SCUBA testing testing station and have the facilities to test any pressure vessel up to 400bar.

its hardly dangerous hydraulic testing boilers or pressure vessels filled with water . u can easily make the pumps or buy one if u havent the gear http://www.online-pumpshop.com/xcart/product.php?productid=331

 

[Mr shiney]

I don't recall saying it was dangerous. We test to 400bar which is a big more than testing a boiler and requires a few extra precautions. A receiver or a boiler letting go at test pressure is just going to leave you wet. A SCUBA cylinder at 400bar is more of an issue, 400bar water will go through you like a plasma cutter.....