Check Valve for Moisture Filter - "Gold Filter"

[hollowpoint1911]

I've had a few people ask me about this, so I thought I'd create a post to share the info with everyone though I'm not the first/originator and take no credit.

I recently added a check valve to the end of my moisture filter. I did this for 2 reasons, to frequently open the high pressure bleed screw on the Yong Heng compressor to remove accumulated water, and to prevent air from my SCBA tank from escaping in the event of a compressor/fitting/hose failure. In the early days of running my compressor, I had 3 different Chinese quick disconnect fittings fail on me around 4000psi, and ever since then I'm constantly thinking about the what-ifs when a large volume of high pressure air gets released.

Last week I fired up my compressor with check valve installed and filled 2 of my SCBA bottles. With the check valve on the moisture filter output side, I cracked the high-side bleed screw about every 2 minutes and in a 10 minute session I purged enough water to thoroughly dampen a rag. In order for this to be effective, note that the moisture filter (input side) must be located HIGHER than the compressor's output so that moisture can pool up by the high pressure bleed screw.

Here's a picture of my check valve setup:


This is the breakdown of the exact parts I used. You could probably save some money by using less stainless steel fittings or finding some fittings on eBay/AliExpress, but due to my bad luck with cheap fittings...I'm ok with paying the premium.

• M10 Male to 1/8 NPT Female, Stainless Steel (PN: SS-9235-10-02) - $24.87 from Hydraulic Hoses - http://www.hydraulichoses.com/stainless-metric-to-npt-p/ss-9235.htm
• 1/8 NPT Male to 1/4 NPT Male, Zinc Plated Steel - $1.30 from August Industries - https://www.augustindustries.com/male-pipe-adaptor-1-4-1-8-ff-s.asp?bc=no
• 1/4 NPT Female to Female Check Valve - $54.50 from August Industries - https://www.augustindustries.com/check-valve-stainless-steel-val-ckssff.asp?bc=no
• 1/4 NPT Male to 1/8 NPT Female, Zinc Plated Steel - $1.10 from August Industries - https://www.augustindustries.com/adaptor-reducing-1-4-1-8-ptr-s.asp
• 1/8 NPT Male Foster Fitting, Stainless Steel - $14.97 from Air Tanks Plus - https://airtanksplus.com/product/deluxe-ss-male-foster-fitting-with-male-18-npt-and-removable-check-valve/

The zinc plated fittings from August Industries are stamped made in China, but rated for 6000psi service. They work perfectly fine, but I'm replacing them with stainless steel fittings just because. The male Foster fitting from Air Tanks Plus comes with a little check valve in it, but for this purpose I've removed it. It functions as a straight-through fitting. With all the various fittings available out there, it's possible to install a check valve with fewer fittings than I've outlined above, but I've ordered these parts over the course of a month or so with different end goals in mind. If any of you guys go down this route using quick disconnects, I'd recommend you don't mix/match 1/8 NPT Foster fittings and 8mm quick disconnects from China because there's the possibility they won't stay coupled at high pressures even though they might seem to connect to each other. I've spent a ton of money (more than the cost of the compressor) to convert my compressor and fill station over to NPT so I don't have to deal with NPT, Metric and British. It was painful to get here, but I'm hoping it results in less trouble down the road. Let me know if you have any questions!

[mr.grimm]

I use a check valve on mine also but I went with a simpler lower cost version. I used the male foster with check valve from Air Tanks Plus with another regular male foster attached to it. Made a male to male connector with a check valve in it. Total cost was about $25.00

[Bigragu]

Thank you, Andy!

[lennyk]

thanks

airtanksplus is out of stock on the male foster with female threads
I bought the female foster as i have a male to male which I'll use in the female

I use a check valve on mine also but I went with a simpler lower cost version. I used the male foster with check valve from Air Tanks Plus with another regular male foster attached to it. Made a male to male connector with a check valve in it. Total cost was about $25.00

[lennyk]

I used the check valve for the first time yesterday, works great and filling noticeable faster now.
I like to bleed both low and high every minute or so as I live in the tropics.

Thanks again for the info.

[tracker1955]

I'm doing something similar except I have the check valve on the inlet of my second stage moisture trap, this lets me back pressure the filter with the molecular sieve from my tank keeping it under higher pressure to remove the last bit of moisture,, but I can still bleed the high side every few minutes without losing so much air.

[BSJ]

I use one of these on my gold filter.

Just make sure the brass part is below flush so that the fitting will seal against the white disc in the filter's end cap.

The check valve fitting goes on what is now the Inlet end, and the other male fitting becomes the Outlet, to tank end.

[Humdinger]

You can add a one way check valve to a Gold filter for $2.65 including shipping from Aliexpress.  The thread on the check valve that fits the Gold Filter is M10*1.  Here's the link:

https://www.aliexpress.com/item/New-Paintball-PCP-8MM-Male-Quick-Head-Connection-Check-Valve-One-Way-Foster-Stainless-Steel-Fill/32658889691.html?spm=2114.13010708.0.0.44164c4dKqzj7P

[hollowpoint1911]

I just wanted to add...there are MANY ways to do this cheaper/more efficient than I did. I'm glad guys are finding cheaper ways to add a check valve to their setup because I think it's a really important thing to have on these compressor setups!

My primary reason for choosing the parts I did was to eliminate as many Chinese fittings from the setup as possible, and convert things over to NPT so that I could source replacements from a stateside vendor if I ever needed it. Before switching to this setup, I had M10 quick disconnects blow apart and hose whip me. It only takes a few of those events for me to totally reevaluate if it's worth personal injury for air independence.

Part of me thinks I had really really bad luck with these Chinese M10 fittings, so by no means am I saying that all these Chinese fittings are subpar. There seems to be plenty of guys running them without issue. The only thing I would warn others about is to try your best to make sure you're actually getting steel or stainless steel fittings. I did some scratch testing on some of my old fittings and found that some were zinc plated brass. Brass fittings in these small sizes aren't really ideal when you're trying to hold 4000-4500psi. For reference, Foster Mfg states the rated working pressure of their brass quick disconnect socket to be only 2500-2600psi compared to stainless steel at 4200psi (which we all exceed when we use them at 4500psi, though there's a little head room since these rated pressure numbers are using a 4:1 safety factor). Long winded summary.... Just be safe out there guys!

[essbend]

For those of you using a male foster with a check valve, do you know which way the air flows? I assume it's from the foster end to the threaded end. Can you change the direction of the check valve? The reason I ask is because I was thinking to use the same fill whip I use for filling my PCP from my SCBA to fill my SCBA from the compressor, and therefore I would need a male foster at the output end of the filter, but I obviously don't want the check valve blocking the output of the filter.

[tracker1955]

Sorry, but you can't change the direction of flow but what you'll need is a stainless steel male x male foster fitting like this one from Amazon.