Replace Unloader Valve - CH 631400AJ

1 week 5 days ago #2596 by drjohn

I'm trying to replace the Pressure Switch on my CH 631400AJ. I am stumped at how to connect the unloader valve to new switch. I purchased it from AirCompressorPartsOnline. It was supposed to be an exact replacement.

In the picture below, the old unloader valve and tube is shown at left. The new unloader valve, integral to the new switch, is shown at right.

It seems to me that I should just move the tube and fitting to new unloader. However, try as I can, I can't get the fitting and tube out of the old unloader. I tried grabbing the knurled fitting with pliers and pulling but it just wont budge. The fitting does rotate freely, implying to me that there's some kind of latch release, but for the life of me I can't find it.

Is there some secret? Did I buy the wrong part? Did I fail to buy something extra? I feel king of stupid asking this question but I'm stymied (I'm an amateur in these matters).

Another general question: In my research I read that the unloader valve is supposed to vent pressure above the cylinder(s) to the atmosphere when pump stops to allow easier re-starting. But in my case, the tube goes to the main air tank not to atmosphere. Am I totally misunderstanding the operation of this device?

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1 week 3 days ago #2601 by MTR-Admin

Thanks for the post drjohn,

That pressure switch is the direct replacement, but it's very common for the manufacturer to change the type of switch on their units over time. Different switches may have different unloader valves.

The valve you received on your new switch should certainly accept your original 1/4" nylon tube, and should install. It's a "QC" quick-connect fitting so you [should] be able to press the tubing into the new unloader valve (with some force) so it locks into place. You shouldn't be able to pull it out easily once it's installed.

When the unloader valve actuates after the unit shuts off at max PSI, the air isn't unloaded into the atmosphere from the pump head, it's unloaded directly at the Unloader Valve itself, at the end of the valve where it installs into your switch. Some valves have a small weep hole that unloads the air.

Hope this helps, reply if you need more info or if you have additional questions and I'll try to assist you further.

- MTR

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6 days 23 hours ago #2610 by drjohn

So if I understand correctly, I need a "Quick Connect" (QC) to fit my new unloader, right?
I'm guessing the QC is a small fitting that plugs into the unloader on one end, and has a 1/4" hose bard on the other end?

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4 days 4 hours ago #2616 by drjohn

More Dumb Questions...
1. Just to get my terminology straight: the part I labeled New Unloader in my picture; that is what's actually called the "Unloader Valve" right?
2. The old tube on my compressor is 1/4" O.D.. I suspect it is more like 1/8" I.D.. Is that what you refer to as the "1/4" nylon tube"?
2. If I understand you correctly, the bare tube should press-fit into the unloader valve, correct?. I can't see how that would work because the opening in the new valve is 5/16" (?).

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2 days 1 hour ago #2623 by MTR-Admin

drjohn,

1. Just to get my terminology straight: the part I labeled New Unloader in my picture; that is what's actually called the "Unloader Valve" right? That's correct.
2. The old tube on my compressor is 1/4" O.D.. I suspect it is more like 1/8" I.D.. Is that what you refer to as the "1/4" nylon tube"? Correct. The Unloader Tube should be 1/4" Outside Diameter, which is the most common size.
2. If I understand you correctly, the bare tube should press-fit into the unloader valve, correct?. I can't see how that would work because the opening in the new valve is 5/16" (?). Correct. The original Unloader Tube should "lock" into place when you press it in. Use some force to make sure you push it all of the way into the valve. The "teeth" inside the valve should grab it and lock it into place. Even if the opening of the new Unloader is larger, that Tube should install.

If you're still not able to install it in the new valve please let me know, I'll contact the manufacturer and talk with them about a solution.

- MTR

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2 days 1 hour ago #2625 by drjohn

Thanks! The tube *did* press-fit into the new unloader despite my misgivings. I'll give it a try tomorrow.

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