Pressure Regulators / Separators

[DunnyD]

Hi all,

I have just taken delivery of my first really decent compressor (36 CFM 2 x 4HP motors, 270 litre tank) and I am just thinking about how it will be piped up. I think I will probably have a couple of questions but the first one relates to pressure regulators / separators.

I have a cheap pressure regulator / separator that I have just been playing with in the garage and this is the only one that I have as a point of reference. Anyway, when you set the pressure on this type of regulator it dumps a load of air so the whole tank pressure drops; this seems incredibly wasteful.

I had expected that it would just meter the output pressure but the tank would remain at a higher pressure. Do all regulators operate in the same way or is it just the fact that my cheap one does??

Thanks

D

 

[rtbcomp]

Sounds like it might be faulty. Some release a small amount of air when you decrease the pressure.

The whole tank pressure shouldn't drop, the whole point of a regulator is to give a supply at a set pressure regardless of the tank pressure. (Obviously the output pressure can't be higher than the tank pressure).

 

[lshigham]

You do have it round the right way don't you?

 

[NickyEng]

Sounds like it might be faulty. Some release a small amount of air when you decrease the pressure.

The whole tank pressure shouldn't drop, the whole point of a regulator is to give a supply at a set pressure regardless of the tank pressure. (Obviously the output pressure can't be higher than the tank pressure).

Sounds faulty to me. The pressure dump is usually the condensate drain operating when there is a lower pressure in the regulator. The regulator just works by reducing the higher cylinder pressure to a lower working pressure as regulated

 

[Wallace]

Should be arrows indicating flow direction. What are you planning to use the compressor for?

 

[DunnyD]

Thanks RTB.

You do have it round the right way don't you?

Yes, it only goes in one way and came assembled. Its a cheap WorkZone one from Aldi. I attached it to my equally cheap Aldi 25 litre compressor and set the pressure on the regulator. It dumped a load of air to get down to the lower pressure and I watched the gauge on the compressor as it did this. Both gauges then equaled out to the same reading. It may be that with the compressor being so small the air it dumps out reduces the tank pressure by a large amount. However I then used an air tool to empty the tank to the point it would restart the motor to build up pressure. When the compressor restarted I was expecting to get to full pressure on the tank gauge (e.g. 10 bar) and the reduced pressure on the regulator (e.g. 9 bar) but they equalized again to 9 bar each.

Doesn't make sense to me!!

D

 

[DunnyD]

Should be arrows indicating flow direction. What are you planning to use the compressor for?

Hi Wallace. It will be used for a number of things but mainly running some air tools and my blasting pot. Maybe at some point I might spray with it too but that's not priority.

D

 

[Wallace]

Go for a good sized supply from the compressor to your blasting pot to prevent any restriction in flow as you want cfm for blasting. It would be a shame to hold all those horses back with a small hose!

From the symptoms it sounds like the regulator might be the self relieving type if you can hear air escaping until the pressure is equalling out on both sides of the regulator. Likely cause would be the poppet valve not seating correctly through contamination or damage.

 

[DunnyD]

Go for a good sized supply from the compressor to your blasting pot to prevent any restriction in flow as you want cfm for blasting. It would be a shame to hold all those horses back with a small hose!

From the symptoms it sounds like the regulator might be the self relieving type if you can hear air escaping until the pressure is equalling out on both sides of the regulator. Likely cause would be the poppet valve not seating correctly through contamination or damage.

Thanks for the steer, I will check.

My blasting pot is pressurised and the manufacturer recommends a direct connection to the compressor with a wide bore fitting if possible (i.e not PCL).

D

 

[brightspark]

I use 15mm bore pipe from tank to blastpot using claw couplings and a half inch -ball shut off at the tank don't restrict the flow

 

[DunnyD]

I use 15mm bore pipe from tank to blastpot using claw couplings and a half inch -ball shut off at the tank don't restrict the flow

On the end of the tank already is what looks like a 1/2 inch ball valve sat behind a threaded female connector (I don't know what size it is though but it looks like it could be 1 inch - I haven't looked properly yet). I only realised earlier today that I am going to have to pipe the compressor up as it has no other connections.

I therefore have to come up with a plan that will incorporate the blasting pot with a straight through connector plus a couple of other outlets, possibly water trap etc.

May have to start another thread for that one!!

D

 

[brightspark]

I use 1 end direct from tank to pot direct the other end of tank filter regulated for air tools and spraying with u wont be disappointed with your comp del;ivering over 28cfm

 

[DunnyD]

I use 1 end direct from tank to pot direct the other end of tank filter regulated for air tools and spraying with u wont be disappointed with your comp del;ivering over 28cfm

That's the way my small compressor is set up but on this one I may tee off the same end just because access to one side may be restricted. I need to work out the size of the connector on the tank as it looks quite big (e.g. inch).

 

[Bill Edwards]

Regulators will usually dump pressure at the outlet side if you lower the pressure while there is air in the pipe. But it should not empty the tank, something is wrong.

I'm jealous of your compressor!

 

[DunnyD]

Regulators will usually dump pressure at the outlet side if you lower the pressure while there is air in the pipe. But it should not empty the tank, something is wrong.

I'm jealous of your compressor!

It doesnt empty the tank completely but it does equalise the pressure.

I have wanted a decent compressor for years and finally took the plunge. Only trouble is that its deffo not plug and play!!

 

[Bill Edwards]

Sorry, it shouldn't empty anything out of the tank to equalise the pressure, the idea is that the tank remains full and you get a lower pressure for where you want it.

I meant to add in my post that you need something of a good size with good size ports, I would think you need 1/2". Also, although this isn't from personal experience not long ago I was in the market for a filter/drier and did some research and it seemed that the cheap ones such as from Aldi are rarely any good and usually give problems/leak etc. It seems that Norgren are the ones to aim for. I found one on eBay that wasn't too bad on price and it certainly seems well built.

 

[DunnyD]

Thanks Bill.

Ishigham, Wallace - you were correct. The flow on the regulator was the wrong way round!! Maybe it didn't come assembled and I made a mistake but I don't remember ever putting it together and its never been used.

Bill - I wouldn't use the Aldi one with my new set up - as you say they are just cheap (OK for occasional use) and the couplings do often leak,

D

 

[DunnyD]

Can anyone tell how big this is please?

It looks like its about 22mm to me??

Thanks

D

 

[rtbcomp]

Is it stamped/cast on the valve itself?

 

[DunnyD]

Good call....3/4 HUK on one side and DN20/PN40 on the other. Presumably therefore 3/4 inch coupling.

Thanks a lot.

D