Sil-Air compressor: filter regulator and auto-off function

by Tristan van der Hoeven
(The Hague, The Netherlands)

Sil-Air airbrush compressor

Sil-Air airbrush compressor

Hi Bill,


I just bought a second-hand Sil-Air airbrush compressor. It's 1992, yellow and a google search indicates it's a Sil-Air 15, but with a case (yellow). 20 liters a minute, 6 bar.

The compressor works well.

There's two questions I'd like to ask you:

Looking through the glass of the filter regulator, it shows small pieces of rubber in it. My guess is, this must be the rubber 'seals' slowly disintegrating. Should I be worried and replace the costly filter regulator?

The second question is about the auto-off function. It doesn't seem to automatically turn off the compressor at a set pressure. I wasn't able to find out whether or not this model even has an auto-off function.

The guys who sold me the compressor mentioned Werther's customer service people not responding to his questions.

I hope you can help me with the answers?

Very much appreciate your time!

Tristan

Comments for Sil-Air compressor: filter regulator and auto-off function

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Feb 07, 2016
same compressor same problems same country :)
by: Josef

Hi, I have the same issue with this compressor, it is on loan here from a friend who has not used it for years. I will not shut off, it will keep on pumping even after the manual release valve starts leaking air, took this apart,(the valve) cleaned it, and no prize, seems the auto switch of does not work properly, has anybody had the same issue resolved, mailed sil-air/werther but no reply yet.
I had some debris in my regulator glass, it was probably some rust formed in the tube which is in fact the tank, which seems to be just a standard bit of steel bent tubing, with end caps welded onto it.
silent air is extremely vague when it comes to diagrams and exploded views

Apr 06, 2015
Sil Air behavior
by: Bill

Nope, it doesn't. The pressure relief valve is not supposed to open until the pressure in the tank bypasses the normal cut out pressure setting of the compressor. It's a secondary defense against over-pressurization in the event that the pressure switch fails.

I cannot tell from your original photo if this model has a pressure switch or not. From what I have read I believe it does.

What I don't know is the normal cut out pressure setting of your compressor. I expect it to be in the 6 bar area, and if so, that your PRV lets go before then suggests to me that the PRV has failed.

What may have affected it is the "black shiny material" you are seeing in the filter. If it is what I think it is, burnt oil, that suggests that your air compressor has run way to long, maybe way to often, and it's actually burnt some of the lube oil that wicks onto the cylinder wall. That burnt oil may be flaking off and getting into the air stream and some may have entered and affected the operation of the PRV.

Find, if you can, the serial number on the pump and any other places you find one, and email the source that I referred to earlier. Ask what is the normal cut in / cut out off your compressor to determine if it is working within safe parameters.

Apr 06, 2015
update
by: Tristan

Hi Bill,

Thanks, I've cleaned the debris. After a while however, new debris build up. It doesn't seem to be oil or rubber. It looks small, shiny and black.

Sorry I wasn't clear on the other part; let me try again.

The compressor quickly gets to about 4 Bar, once turned on. At about 4 Bar, I start noticing the pressure valve starting to make a hissing sound. Eventually, the compressor will get to a little below 6 bar maximum pressure.

With a closed pressure valve (pushing it with my finger), the pressure will quickly get to 7 Bar, at which point I start to worry ;-) and let go of the valve.

Does this sound like normal behavior to you?

Cheers,

Tristan

Apr 05, 2015
Sil Air
by: Bill

"It's this part you mentioned and can be unscrewed?" Yes, that's the part.

Sorry. I'm not understanding this: "The compressor quickly reaches 4 bar. This is when the valve comes in. It'll probably get to 6 bar or a little more. To test it; I kept the pressure valve from releasing air and then it went up to 7 bar easily, which was when I released the valve and outlet."

Apr 05, 2015
Thanks Bill
by: Tristan

Thanks Bill.

I really appreciate your help!

The bowl of the f/r is made of clear plastic. It's this part you mentioned and can be unscrewed?

The compressor quickly reaches 4 bar. This is when the valve comes in. It'll probably get to 6 bar or a little more. To test it; I kept the pressure valve from releasing air and then it went up to 7 bar easily, which was when I released the valve and outlet.

Thanks also for the email address.
I'll drop customer service a line.

Happy Easter,

Tristan

Apr 05, 2015
Sil-Air airbrush compressor
by: Bill

The combination Filter/Regulator is doing it's job, in that it is filtering out debris from the air supply before it gets to your airbrush. I'd be worried, not about the F/R, but about where else the seal material may be coming from.

You should be able to - with the tank empty and compressor off, to unscrew the bowl on the filter to empty out debris. With a clean bowl you will be able to tell if you are still getting seal disintegration in components.

As to shutting off, the images I've seen of this compressor show that it comes with a pressure switch that starts the compressor when low pressure cut in is reached, and shuts the air compressor off when the high pressure cut out level is reached.

If the compressor isn't shutting off, what's happening to the pressure level? Is the pressure relief valve letting go to vent over pressure? Or, is the pressure in the tank not getting high enough to do so? Please advise.


In terms of getting questions answered, why not contact the manufacturer directly. They indicate that they would be pleased to answer any questions about the Silent Air products.


Email: techsupport@silentaire.com

Bill

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