Cheap, suitable one way valve for aspirator vacuum pump?

[joniverson]

I have a glass aspirator vacuum pump that has a built in one way check valve, but after a week of use, it no longer functions and when input water is turned off, there is a sudden backflow of water into the vacuum line. I'd like to add a one way valve inline to allow the vacuum pull but not water reverse flow once the input water is shut off. What would be a suitable, cheap valve? First thought was to use an aquarium check valve, but I'm reading that they restrict desired flow too much (which in my case would be the vacuum flow). Thank you!

 

[Ranger Mike]

https://www.mcmaster.com/#check-valves/=19ow0d2

 

[joniverson]

Thanks, Ranger Mike, but I tend to avoid them due to unusually high shipping amounts. I found something similar on eBay though that I think will work. Appreciate your initial pointer.

 

[Tom.G]

I have a glass aspirator vacuum pump that has a built in one way check valve, but after a week of use, it no longer functions and when input water is turned off, there is a sudden backflow of water into the vacuum line. I'd like to add a one way valve inline to allow the vacuum pull but not water reverse flow once the input water is shut off. What would be a suitable, cheap valve? First thought was to use an aquarium check valve, but I'm reading that they restrict desired flow too much (which in my case would be the vacuum flow). Thank you!

Sounds like the check valve is dirty. Could be that there is a mineral buildup in it. Try soaking it in warm White Vinegar overnight and flush it well in the morning.

If that doesn't fix the problem, do it again with some salt added to the vinegar. The salt and vinegar react to form Hydrochloric acid (HCl), which is much more active than the plain vinegar. Watch out for materials in you device that HCl will corrode, such as steel or any organics.

 

[joniverson]

Sounds like the check valve is dirty. Could be that there is a mineral buildup in it. Try soaking it in warm White Vinegar overnight and flush it well in the morning.

If that doesn't fix the problem, do it again with some salt added to the vinegar. The salt and vinegar react to form Hydrochloric acid (HCl), which is much more active than the plain vinegar. Watch out for materials in you device that HCl will corrode, such as steel or any organics.

Tom, thanks. Nice idea, but in this particular glass aspirator, the valve appears to be some form of flexible plastic, almost like foam. At one point when pressure/ vacuum were reaching high levels, the foam broke away from its position and is now just floating around inside the aspirator body. So, sometimes it would happen to float back over the vacuum port once flowing liquid was stopped, and prevent any sort of water backflow; other times it doesn't even come close. Unfortunately, no way to fix without breaking the glass hence the need for an external valve.

Other than that, the unit seems to be doing a decent job. With hose clamps around all connections and using a 5L/min pump, I am getting 29" Hg. I can get more with ice water, close to 30" Hg, and I have just been thinking of switching to mineral oil as I'd only need about a gallon, but I have to be sure the check valve is working first or oh what a mess awaits!

 

[Tom.G]

Oh well, sounds like you are stuck with replacing it.
Hmmm, I wonder how they got the foam in there in the first place. Black Magic? Or did they add more glass far enough away from the foam to avoid thermal damage?

 

[Nidum]

A manually operated shut off valve would probably be more reliable . Could be a proper screw down or plug cock valve - though a simple pinch valve might be worth trying first .

 

[joniverson]

Oh well, sounds like you are stuck with replacing it.
Hmmm, I wonder how they got the foam in there in the first place. Black Magic? Or did they add more glass far enough away from the foam to avoid thermal damage?

Here's an image of it I found. Almost looks like they did add glass after placing the valve.

 

[joniverson]

A manually operated shut off valve would probably be more reliable . Could be a proper screw down or plug cock valve - though a simple pinch valve might be worth trying first .

Yes, I was thinking of that originally. Since the backflow only seems to occur once the liquid flow through the device is stopped, I could conceivably have a manual valve on the vacuum side that would be shut off just before the main flow is stopped.

 

[Tom.G]

Here's an image of it I found. Almost looks like they did add glass after placing the valve.

Yea, looks like the final piece on the vacuum port was added; possible glued in (with sodium silicate solution?) after foam insertion. Ah well, gives you something as a curousity-satisfier when the rest of it becomes non-functional.