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Throttle unloader for Gasoline powered Air Compressor.


hoary's Avatar
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01-04-13, 09:22 PM   #1  
Throttle unloader for Gasoline powered Air Compressor.

I have the engine, compressor, tank, belt...everything but that unloader valve.

I'm really considering creating an electrical setup to shut the engine back to Idle when the Tank is full, and pull the throttle open when the Air Pressure is down.

Who's done this already?
Does anybody have one of those unloaders I can buy cheaply?

 
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01-04-13, 10:05 PM   #2  
There's a company that sells them on Ebay for about 40.00

Gas Air Compressor Pilot Check Valve Unloader Valve Combo 95 125 NG7 | eBay

 
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01-04-13, 10:06 PM   #3  
If you throttle the engine down, you will still need to unload the head pressure or it will stall the engine and/or keep building pressure.


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God bless!

 
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01-05-13, 04:05 AM   #4  
That valve in the link replaces your check valve and is the only way you can do it safely.
You would need in addition to that a small air operated cylinder that would pull the throttle when the tank is calling for pressure.
When the compressor goes to low idle that valve dumps all the air being pumped to keep tank pressure from building.


GregH.........HVAC/R Tech

 
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10-28-13, 02:51 PM   #5  
I know the little unit is available for $38-$65 but I would rather not spend that much as we don't have a Larger income.

I finally out-thunk the little 'unloader' unit.

First cylinder (Throttle Down Plunger) is the pop-off valve. At max pressure, it 'blows' open and a small stud pop's up.
That Small Stud is wired to the Throttle, which pushes or pulls the throttle back to Idle.

Second cylinder (Throttle up plunger) is forced open at the start of Compressor filling.
When it reaches a set amount (about 60Lbs) the Plunger moves out, and stays out until the Air pressure in the Tank drops below 60Lbs and the Plunger retracts.
This one's linked to the Throttle, and pulls it open.

Now I wonder at the 'burst' pressure of ABS or will I have to use Conduit?

 
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10-28-13, 03:19 PM   #6  
Now I wonder at the 'burst' pressure of ABS or will I have to use Conduit?
Where are you using the plastic? ABS drain piping is not certified for ANY pressure.

 
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10-28-13, 03:26 PM   #7  
Ever had the displeasure of seeing the pictures of an air compressor tank that's exploded?
I'd guess not.
It's a potential bomb.
Oh goody you saved $40.00.
Is that what we should tell your family?
When I used to work on compressors for a company that sold them I've shut down whole factory's when I've seen where one's by passed safety features, welded on a tank, ECT.
pictures of compressor exploding - Bing Videos

 
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10-28-13, 03:31 PM   #8  
Hello hoary,


What you are trying to do is unsafe.....

1) There's different pressure pop off valves, They are designed to pop off to keep the tank-compressor and lines from bursting (safety). I wouldn't suggest continuously over pressurizing these items the way you planed.

2) The center pin in a pop off valve doesn't move enough to reduce engine RPM low enough for continuous use.

Second cylinder (Throttle up plunger) is forced open at the start of Compressor filling.
When it reaches a set amount (about 60Lbs) the Plunger moves out, and stays out until the Air pressure in the Tank drops below 60Lbs and the Plunger retracts.
What do you plan on using for this ? ^^^^^^ A pop off valve will not work backwards.....

 
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10-28-13, 06:41 PM   #9  
I agree.

Your risking you and other's safety for the sake of a few bucks is not right.

To call it a pop-off valve is a somewhat fuzzy term for what is actually a pressure relief valve.
It is only meant as a safety control and not an operating valve.
If you continue to use it like this it will fail and not work as it should.

Do the right thing, disconnect what you have done and buy the correct part.


GregH.........HVAC/R Tech

 
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01-14-14, 12:34 AM   #10  
OK, you guys win. I'll spend the money.

 
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