Compressor drain off plug

[opps]

Hi all.

My old Nardi compressor drain off plug fell apart a while back. In the meantime I have just screwed a bolt in.

It is identical to this one (but white rather than red).

https://www.fps-compressors.co.uk/silverstone_silenced_230v.html?category_id=1933

I take that the bolt will suffice. It doesn't act as a pressure relief valve does it?

The other problem that I have with it is that it doesn't know when to stop. By that I mean that it doesn't automatically stop when it reaches 10 BAR. It doesn't actually manage to get over 10 BAR but left to it's own devices it would just chug away until I turn it off.

Having looked at the specs listed in the link above it looks like part of the problem is that the compressor has been set to 10 BAR even though the specs say that the max pressure is 114 PSI (7.86 BAR). How do I adjust the upper and lower limits- I guess I just twist the red pressure regulator knob to lower the desired pressure. The compressor is normally used for light dusting and with an 18g pin gun.

Thanks in advance.

 

[Deleted member 174758]

There is normally a black box on top of the compressor which contains a regulator switch. This is wired to the motor to control the switching on and off of the motor at both minimum and maximum pressure respectively. They do fail over time, but can be repaired. Look for "Barry's Workshop Repairing a Compressor Switch" which might help you.

To continue running with a defective pressure switch is potentially hazardous as it leaves you dependant on the pressure relief valve/unloaded as your sole safety mechanism - and they can jam or fail, too

 

[Harry Bloomfield]

A bit of guessing here, based on my own compressor...

The red knob only sets the output pressure, which is lower than the stored pressure.

The black box mentioned above will include a pressure switch, that needs adjusting so the compressor does switch off. There will not be a separate lower limit setting, that lower limit will be a little lower than your pressure switch setting. Probably a single screw in the top of the cover holds it on.

There will be a safety pressure relief valve somewhere very close to the tank, that might be leaking pressure - causing the motor not to cut off, my pressure relief has a key ring through it. The valves are usually adjustable, if set to trigger to low - it might explain the problem.

Your drain plug is just a condensate drain plug, if a bolts fits and manages to seal, it will be fine. I welded a washer at right angles to my drain valve, so that I could turn it to release the condensate without need for a spanner.

 

[opps]

There is normally a black box on top of the compressor which contains a regulator switch. This is wired to the motor to control the switching on and off of the motor at both minimum and maximum pressure respectively. They do fail over time, but can be repaired. Look for "Barry's Workshop Repairing a Compressor Switch" which might help you.

To continue running with a defective pressure switch is potentially hazardous as it leaves you dependant on the pressure relief valve/unloaded as your sole safety mechanism - and they can jam or fail, too

Thanks for the heads up. Much appreciated. Will check out Barry's workshop.

 

[opps]

A bit of guessing here, based on my own compressor...

The red knob only sets the output pressure, which is lower than the stored pressure.

The black box mentioned above will include a pressure switch, that needs adjusting so the compressor does switch off. There will not be a separate lower limit setting, that lower limit will be a little lower than your pressure switch setting. Probably a single screw in the top of the cover holds it on.

There will be a safety pressure relief valve somewhere very close to the tank, that might be leaking pressure - causing the motor not to cut off, my pressure relief has a key ring through it. The valves are usually adjustable, if set to trigger to low - it might explain the problem.

Your drain plug is just a condensate drain plug, if a bolts fits and manages to seal, it will be fine. I welded a washer at right angles to my drain valve, so that I could turn it to release the condensate without need for a spanner.

Thanks Harry, top stuff. I suspect you might be correct about a leak. I will mix up some soapy water and check the joints.

After posting my question I headed off to eBay and invested a whole £1.99 in a new 1/4 inch drain plug from Chengdu Baixingle Wangluokeji Youxiangongsi (China) that can be undone by hand. If it doesn't fit I have only lost half a pint of beer *sighs- not like I can buy a pint at the moment anyway*