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Discussion Starter · #1 ·
Hello,

I'm looking for a check valve I can use
for preventing water backflow into my CO2 line as well as use in a fertilizer dosing application. The tubbing I am using is 1/4"od and 1/8"id.

Ideally, I'd like to find something with a cracking pressure of ~0.5psi only because of the check valves I'm currently using don't seem to prevent black flow when the back pressure is very low. TIA!
 

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For co2 I've used those metal check valves from amazon or ebay for a few years without problems. Has some mixed reviews but I think its mostly from people trying to use it with air pumps, not sure about the cracking pressure but I've never had back flow.
 

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Hello,

I'm looking for a check valve I can use
for preventing water backflow into my CO2 line as well as use in a fertilizer dosing application. The tubbing I am using is 1/4"od and 1/8"id.

Ideally, I'd like to find something with a cracking pressure of ~0.5psi only because of the check valves I'm currently using don't seem to prevent black flow when the back pressure is very low. TIA!
I've used some cheapy ones I buy from amazon which use a rubber-like diaphragm but have had bad luck with them. I have switched to buying these guys from Mcmaster Carr, so far so good. They use a stainless steel ball bearing and a spring to work which has proven more reliable.
 

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There's no specific brand I prefer but I've found it easiest to buy a few different (cheap) types on fleabay to see which work best. They all ultimately fail - eventually - so I also like to buy multiples.
Agree with @somewhatshocked, they all fail.

I've used cheap and expensive, none will stop the water from getting by. The gas/water pressure must equalize, and only then will the check valve hold the aquarium water back from getting to the regulator. The failure point is the water going back and forth thru the valve over time.

Cheers
 

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I've used some cheapy ones I buy from amazon which use a rubber-like diaphragm but have had bad luck with them. I have switched to buying these guys from Mcmaster Carr, so far so good. They use a stainless steel ball bearing and a spring to work which has proven more reliable.
If you poke around fleabay a bit, you'll find multi-packs of those for cheap. Similar to what I've been using.
 

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Discussion Starter · #8 ·
For co2 I've used those metal check valves from amazon or ebay for a few years without problems. Has some mixed reviews but I think its mostly from people trying to use it with air pumps, not sure about the cracking pressure but I've never had back flow.
I might give these a try for CO2 but I don't know if they are rated for liquid. Thanks for the recommendation.

If you poke around fleabay a bit, you'll find multi-packs of those for cheap. Similar to what I've been using.
These look like the ticket. I think I am going to go this route. Thanks!

These are commonly used. Best to use more than one in line

Next best working for me ( until they don't) was the Ista check valve.
These are the check valves that I'm currently working with. They only "check" the backflow when there is enough back pressure. I can pick one up and blow through it (in the intended flow direction), then reverse the flow (suck in the opposite direction) very slowly and it will allow air to flow. They're almost a decade old at this point so maybe that has something to do with their functionality...
 
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