Pressure relief valve replacement

[luke123]

Just after some advice, put a new to me (second hand) pump on this clarke compressor, But this valve wont stop releasing air so the compressor cant hold the pressure or atleast go above 30psi in the tank

 

[brightspark]

is it blowing off . the safety that is not the pressure switch there normally adjustable with a ball bearing and spring

 

[daleyd]

I’m not sure what the question is?

 

[Anguz]

got a picture of the leaking item?

 

[luke123]

Should be able to see the valve im on about, it wont stop blowing off upto 30psi approx

 

[mike os]

is that in the bottom of the tank?

 

[Anguz]

gguess thats in the line between the tank and compressor?
if so it's the valve that, vents the comp when it stops so it can restart not under load
prob got a bit of muck in there and not reseating properly
they normally leak for a few seconds on startup
other alternative is the compressor is worn out andnits not generating enough pressure quick enough to shut the vavle

 

[Seadog]

The valve is rated at 2.2 bar if I'm reading it correctly. That's around 30psi. Are you sure that you have the correct item fitted?

 

[brightspark]

The valve is rated at 2.2 bar if I'm reading it correctly. That's around 30psi. Are you sure that you have the correct item fitted?

looks like the wrong one if its the safety valve on the tank if its the case u can get adjustable ones and it wants setting up about 5psi more than the pressure switch max setting

 

[luke123]

Hi, nope doesn’t fit in the bottom of the tank, here are some more pics, The pump itself is not of this model of clarke compressor, as you can see on the pump on the cylinder head where the valve fits

 

[daleyd]

Are you saying that plug is here....

.....as that would suggest it's the oil filler/breather. If this is blowing off then you have some other issues as the crankcase is getting pressurised.

 

[carbon]

My three phase compressor has one similar fitted in the outlet of the pump but has a plastic cap over the end so can’t see what pressure it’s rated at, the plastic cap is not screwed on and I don’t want to break it removing it but would have thought it’s rated higher than 2.2 bar otherwise it won’t get up to pressure. The single phase one I have doesn’t have one fitted in the outlet

 

[luke123]

Are you saying that plug is here....
View attachment 245702

.....as that would suggest it's the oil filler/breather. If this is blowing off then you have some other issues as the crankcase is getting pressurised.

My fault, no sorry 3rd picture in

 

[brightspark]

My fault, no sorry 3rd picture in

buy a new one rated over your cutout pressure theres your problem

 

[luke123]

So a couple of questions, do you know where i could purchase a like for like valve?

So i was looking beforehand, the pump looks like it’s a 3phase unit as someone also mentioned in this thread, so i did some more research the valve is used to release pressure for easier startup on 3 phase motors and then wants the tank has the required pressure it shuts itself of (the valve) and then the motor moves on to the next windings to work the pump? Or is that what I’ve found aloud of twoddle So question is can i just put a bung in it as im running it on single phase?

 

[Al Strachan]

if you have a single phase pressure switch that has the built in pressure relieving valve, then you maybe don't need anything additional, but i have a sealey 3hp single phase compressor that has one of these valves in addition to the regular one on the switch, so you might need one still to let the compressor get up to speed (even moreso than a 3ph motor).

if you do have the function on your pressure switch, i would blank it and see if you get good starts. if it does struggle to get up to speed then replace the valve. That is of course on my understanding that this is a valve (same one as mine) that sits open to atmosphere and closes once it see's pressure inside the pipework.

EDIT, and also assuming you have safety valve already protecting from overpressure - 9 or 10 bar approx.

 

[carbon]

Machine mart sell a 11 bar one but you need to check the pressure rating of the reciever is higher than the safety valve

 

[daleyd]

Machine mart sell a 11 bar one but you need to check the pressure rating of the reciever is higher than the safety valve

I don't think these are safety valves, these are in the delivery line and bleed off the air when the compressor stops, as AL Strachan mentions above. I'd order one from Machine Mart, I think item 23 on the pic below....

I've never ordered spares off them but I've heard a few people say their parts dept are OK.

 

[daleyd]

From the manual.....

NOTE: When starting compressors up to and including the 3HP models, an auto bleed valve will operate and air will be heard vent. This is quite normal and should not cause concern. The valve should close after several seconds. Should it fail to close, consult your Clarke dealer.

 

[carbon]

On mine the part is listed as a safety valve, item 34 on the linked website https://aircompressorpartsonline.com/twostage-air-compressor-pump-parts-b6000-p-3750.html.