What kind of Check Valve is this?

[GabrielNogueira]

Hi,


Was I looking which type of check valve was being used in some existing systems, on the lines of N[sub]2[/sub] for inertization.
And I came across this strange body Check Valve.

Take a look at the photos.

What valve is this, what would be its description?

 

[pennpiper]

Based on the internals you are showing I would say that is a real old version of a "Swing Check Valve"

prognosis: Lead or Lag

 

[bcd]

And what looks like a nice blue-colored asbestos gasket.

 

[gerhardl]

As known: the purpose of a N2 blanketing system is to keep a constant, but very low, N2 overpressure inside the protected enclosed system (for instance inside a tank, above a fluid) to replace oxygen, to protect the fluid from oxydiation.

One way to do this is to have an active inlet, but sometimes also a controlled outlet, at minimum values because of cost.

Anyway, balancing the inlet and outlet, and as a result the pressure, is quite an art, and will need advanced and special valves if you use a purely mechanical solution. Today you will probably come better out with electronic control.

Without seeing the whole system,or exactly knowing the check-valve, it is not possible to describe the valve's purpose. Construction indicates a throtteling inlet function, perhaps two-ste: higher inlet at higher pressure difference??????.

Even if I am wrong on this, I believe the valve to be dimensioned to be a part of the pressure regulating function.

 

[GabrielNogueira]

Thanks for reply.

 

[Artisi]

Yes, it looks like some sort of controlled throttling NRV. But that's a guess on my part.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[MikeHalloran]

One big difference from a more classical swing check is that there's no penetration for the hinge pin; it's entirely internal.

Absent some clocking feature that I don't see on the exterior, it would be real easy to install it upside down, which is not ordinarily a desirable feature in a gravity- closed check valve.

As Artisi says, maybe it's not supposed to completely close, but just sort of buzz.

It's also odd that the seat appears to be welded in place, not cast integrally. Maybe it's a different material from the body?




Mike Halloran
Pembroke Pines, FL, USA

 

[Artisi]

Yes, I looked at the welded in seat, that's what makes me think it is so sort of controlling device, the seat is sized for the wanted / anticipated flow or pressure drop required.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

It looks a bit odd, but appears to me to be a simple swing check valve. No doubt under the mass of paint there is a "TOP" line stamped on part holding the disc, but the top photo seems to show it as the injection port due to the direction of the flapper. It just looks like it is easy to take apart and replace the seal plug.

It would appear to be easy to install upside down, but there is no evidence to me that it is anything other than as straightforward small swing check valve.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[gerhardl]

Speculation again: ordinary swing-check, where the 'regulation' possibillity is the easy demounting of the inner disc including the checking device, to be replaced by an equal disc with a larger or smaller opening check device? (But I really can't see the purpose of this.) Home-made throtteling adaption?

 

[tr1ntx]

I don't think that is a weld bead around the bottom of the seat. I think it's the remnant of the original cast embossment that has been machined away.