Check-Valve

[ARNWD]

Mr (& Mrs Postman) have just delivered a check-valve/demand-valve that involved me running out into the street in my underpants. I thought the knocking was the cat misbehaving again!

The check-valve is a different model to the one I ordered, I ordered the cheapest and the one received has the text clean on a sliding two position tab. Is anyone familiar with this type? Do I need a splitter preceding the valve for the cleaning line?

My original intention was to disconnect from the PB and draw cleaner through that way. Any advice would be appreciated.

[PeeBee]

No-one could answer this?

Probably too late for ARNWD who'll have sorted it by now, but I only use the ones with a "clean" lever. The lever just disengages the "demand" mechanism, so it doesn't interfere with flow. Handy if you want to pump (push) cleaning fluid through it and through the downstream hand pump. Of little value if you pull cleaning fluid through it with the hand pump.

Don't forget to push the lever back to "serve" when you attach a keg or cask or the valve will function as if it wasn't there.

It works whether wearing underpants or not.

[ARNWD]

Hi PeeBee,

Yes I did work out what the lever did but not why.

Your explanation of pumping up from a cellar makes sense now.

Thanks for the eventual responce.

[MashBag]

Pleased this is sorted, but I read it twice.
Sorry twice at the time and then again just now.
And had no idea what it was. Sorry

I got spunding valve on my head and then was all at sea

[PeeBee]

Heck, the things I must do for you (Mashbag)! (To be honest, I had to read my own explanation a couple of times before it twigged again ... but then me 'ead was shifted to a different astral zone a while ago, I'm surprised anyone can understand me).


Textual diagram (saves on my drawing abilities):

Handpump<----------check-valve<----------keg/cask/bucket

The "check-valve" (one-way valve, demand-valve, we'll come back to that) is fixed to allow flow from keg/cask/bucket (in cellar perhaps?) to hand-pump. But prevents flow from hand-pump to keg/cask/bucket.

In the old-days the check-valve was held shut by a spring. The hand-pump would apply so much negative pressure (suction) it would overcome the spring and draw through the beer. As "check-valves" got better, the strength of spring got less, the valves opened (cracked) with less force until the slightest pressure in the keg/cask/bucket caused beer to flow out of the hand-pump without anyone standing by pumping the hand-pump. What a mess!

So, the spring in the "check-valve" (which wasn't "checking" much at all any longer) was replaced by a system that only opened in reaction to a bit of negative pressure from the hand pump (a "demand" valve). Problem now was if working in the cellar with a bucket of cleaner, no matter how hard you pumped the cleaner liquid you could not get the liquid to pass the "check-valve" (previously, if you pumped hard enough the spring holding the check-valve closed would be over-come). Solution: Disengage the demand mechanism in the "check-valve" so the valve was forced to be open ...

A "clean" lever. (Don't forget to move the "clean" lever back ... to "serve" ... after cleaning).

Get it?

[MashBag]

Smashing yes. Thank you