SpudFiles

Just today I realized my pilot valve has acquired a small leak . This wouldn't be nearly such a concern if I didn't have a sealed piston, since it'd just be a leak. Now, if I let it sit around slowly leaking, eventually the valve will pilot. So I looked up the pressure rating for my current pilot valve, and it turns out that it's only 600psi. Whoa...

Would McMaster item# 4112T21 be a suitable replacement? Or should I look into steel and just steer away from brass entirely?

The most logical thing to do in this case would be to pressurize it then take off the barrel and hide it in a co-workers desk somewhere.

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That valve should be fine, but it depends on whether you want to spend $10 plus shipping on a 1/4" BV. If your piston pilots so easily, flow isn't to important but it might cause a slight delay. Hell, you could probably try a needle valve if you have any laying around.

I doubt steel has any real advantage in this case; it's all in the tolerances. Have you tried putting some thick grease in the ball valve? It can sometimes stop small leaks.

Fnord wrote:The most logical thing to do in this case would be to pressurize it then take off the barrel and hide it in a co-workers desk somewhere.

Would be a great idea if I wasn't almost certain it'd leave a hole in the desk, if only from the recoil.

But anyway... I don't have any other valves laying around, sadly. The current pilot valve has taken such a beating from being used so far past its pressure rating, plus the vast amount of heat produced from compressing are probably just wearing it out.

No thick grease currently in my possession, unless I make something out of beeswax...

what about a power washer handle

Power washer handle might be good. Do many power washers run at and above 1,000psi? Do they have NPT connections? Can one find a small power washer handle? It'd look silly unless it's pretty small...

The slow leak may simply be dirt or something in the seal. Have you disassembled it for a cleaning? The brass ball valves can be opened and serviced.

You could use a paintball slide-check valve, they have 1/8" npt threads and can handle thousands of psi

It's possible that it's a bit of teflon tape, but I'll check it out, and look for paintball slide valves while I'm at it.

Power washer handle might be good. Do many power washers run at and above 1,000psi? Do they have NPT connections? Can one find a small power washer handle? It'd look silly unless it's pretty small...

Not the greatest idea. Although some of them are rated up to 4000psi, they're made for sealing water "good enough", not for sealing air well. I bought a 4000psi one from McMaster which showed small leaks at even 500psi with nitrogen, and developed a very loud hiss at 2000psi. Pressure washer handles just aren't made to the tolerances necessary to seal high pressure gases.

saefroch wrote:It's possible that it's a bit of teflon tape.

Is the valve leaking at the stem seal? I find BV's tend to leak there after many cycles because the stem is so short and lacks bearings/bushings as stem guides. As a result, the stem seal gets chewed in time. If it's the stem seal, you can make one with teflon and a lathe quite easily.

DYI wrote: Not the greatest idea. Although some of them are rated up to 4000psi, they're made for sealing water "good enough", not for sealing air well. I bought a 4000psi one from McMaster which showed small leaks at even 500psi with nitrogen, and developed a very loud hiss at 2000psi. Pressure washer handles just aren't made to the tolerances necessary to seal high pressure gases.

I find it hard to believe that a company would sell a product that didn't work well. It seems yours was defective, or damaged. In my mind, a leaky pressure washer handle would not be sold, especially if the company knew it was not a good product. A leaky pressure washer handle could potentially be dangerous.

also DYI, don't lighter gasses such as nitrogen have more problems with leakage? I have heard of pressure washer handles leaking a tiny bit with unregged co2, but with just a small hiss

Lockednloaded wrote:also DYI, don't lighter gasses such as nitrogen have more problems with leakage? I have heard of pressure washer handles leaking a tiny bit with unregged co2, but with just a small hiss

nitrogen leaks slower than compressed air, ever heard of tires filled with nitrogen?

I find it hard to believe that a company would sell a product that didn't work well. It seems yours was defective, or damaged. In my mind, a leaky pressure washer handle would not be sold, especially if the company knew it was not a good product. A leaky pressure washer handle could potentially be dangerous.

Last I checked, pressure washers used WATER. Gases leak much more readily than water, as you should certainly know. The handle is of high quality, and performs admirably in its intended application. It is now in use by my neighbour, who needed a new handle, as it has been ever since I realized it was useless for my purpose.

also DYI, don't lighter gasses such as nitrogen have more problems with leakage? I have heard of pressure washer handles leaking a tiny bit with unregged co2, but with just a small hiss

Nitrogen (which comprises ~78% of air) has almost exactly the same propensity to leak as air, and CO₂ is useless as a propellant gas, and thus irrelevant to this discussion.

nitrogen leaks slower than compressed air, ever heard of tires filled with nitrogen?

While nitrogen may leak marginally slower than air due to a very slightly higher effective molecular radius, the difference is largely academic. It would be difficult to notice in practical applications, and the nitrogen filling for tires is essentially a scam with a flimsy scientific backing to charge people who don't know what nitrogen is $10/fill.

velocity3x wrote:Is the valve leaking at the stem seal?

No, it's leaking like I haven't fully closed it, not out the stem, but around the seal(s?). Both sides leak. I'm not even sure if my BV has a stem seal, but I'm not about to start tearing it apart without an understanding of how they're put together. I cleaned it out really well, and will re-grease and check for leaks when I get back this afternoon.