Check valve

[Maplewalnut]

Anyone use a 'flapper type' check valve in their vacuum system. Has a hinged cap that opens when the pump is on and drops shut when the vacuum is off. Will this work or do I need a spring loaded check valve to prevent my pump from turninig backwards after the motor is turned off? Seems like the flap will be pulled open towards the vacuum pump for transfer but will the pressure after it is turned off still push it open or is the vacuum downstream of the vavle going to pull it shut tighter.

[Haynes Forest Products]

They will work you need to mount them in the right position. you would want to come out of the vac pump and then go down with the Check valve. Swing checks are subject to the laws of gravity.

[Maplewalnut]

Haynes...to clarify will the flapper open towards to the vaccuum pump or towards the releaser? Seems like it would have to open towards the pump? or I would never get vacuum past that fitting

[Russell Lampron]

Maplewalnut don't you have an SP-22 piston pump? I don't think that you need a check valve with that. It has reed valves that block the vacuum off from the piston and crankcase area.

[Maplewalnut]

Russ- I do have an sp-22. I have the check valve in line already just wondering now if I put it in the right direction. I guess if I didn't really need it, it will act as cheap insurance.

[Haynes Forest Products]

Yes the flap opens in towards the pump. If you get one make sure that the flapper is renforced with a SS washer. If you look at good ones they have a washer that is about as big as the inside diameter of the sealing surface and that keeps it from distorting.

[Russell Lampron]

Maplewalnut,

I just bought an SP-22 yesterday from the same guy that you got yours from. I can't wait to get it hooked up so I can try it out. I had it running in my basement yesterday afternoon and it was pulling a good vacuum and sounded real sweet doing it.

[maple flats]

most check valves will not work well unless there is liquid against. They are poor at holding air/vacuum.

[Russell Lampron]

I used a brass swing check valve with my old vane type pump and it worked well enough to keep vacuum in the tubing system long enough for me to shut the pump off, check and add oil and turn it back on. It would still have 8" to 13" of vacuum in the system depending on if I had to add oil or not. It also held well enough so that the pump didn't turn backwards when it was shut off.

[Maplewalnut]

Russ,

I hesitated buying the sp-22 from such a character but it all worked out. Just kidding, I am thrilled with it, I am changing over my breaker to 220 tomorrow and can't wait to fire it up.