auto closing valve - valve experts?

Does anyone know of a valve that opens with pressure, closes when flow stops, but may still be under pressure? (maybe closed is activated by a pressure spike?)

see if i can explain this simply... A stem would go into the balloon. The stem is 2 inches long and at the bottom of the stem would be a plate. (imagine this as a closed container that can hold pressure) so when pressure comes into the front side of the plate (between the ballon opening and plate, surrounding the stem) it pushes the plate back, and therefore the stem, opening a passage into the balloon and filling it. once the balloon is full, the system should close, but there will still be pressure on the front of the plate trying to push it back.

I guess there could be a spring of some type in back to help it, but whats important is that as soon as it hits a critical filling point (meaning flow has stopped) the valve closes automatically.

now picture 4 or 5 balloon in a row fed from the same source, all stems piped together, one may not be quite done filling because its a different size or type of rubber etc. Hence the reason there is still pressure on the first balloons valve though the cycle isnt fully completed.

there cant be any kind of external activator, or moving device external to the valve. (that would be it too easy) it all needs to be enclosed. size doesn't matter as long as it works. it can have mechanical movement inside the valve if necessary.

any ideas? did i explain it badly?

Sounds like one spring-loaded check valve between each pair of balloons in series. They will all come to the same pressure, minus the cumulative opening pressures of the check valves.

now that I think about it, They would all fill at the same pressure...meaning the lower volume ballon would fill slower than the high volume balloon. increasing the time required to fill. this is what I dont want to happen. Slow fill would cause the material to solidify.

Sounds like you want a differential pressure valve that opens fully and closes when the pressure differential drops below a set point. Unless you have a situation different from what I am imagining, a drop in flow would also signal a drop in pressure differential.

Tom

From what I can make out it is going to have to be sequenced remotely - as in away from the ''balloons'' as in fill each one separately (or all at the same time) using a check valve on each.

That said, material that's time sensitive to solidification and any sort of valve other than single use are bad news, ...............unless by stem you meant to tube type valve that's used on soccer and rugby balls?

??????????? in which case the chemical reaction or heat / whatever that causes solidification, should be kept as close to the ''balloons'' as possible.

A bit more to go on may help

Motorsports-X said:

did i explain it badly?

Click to expand...

Sort of... secret mystery inventions require unusually good reception on crystal ball.

Does the valve need to stay shut/sealed once it seals irregardless of pressure differential?
IE to remove the "ball" or in case pressure further increases or what ever?

nothing really secret. just trying to explain it as simply as I can. Im just trying to find a way to use pressure that's already available to both close and open the same valve. but I cant route the the pressure to the back side of the valve.

There should be a pretty clear "signal" when the pressure spikes that can trigger the valve. I think it may be possible to use some sort of latch that causes a spring loaded valve to close once this signal is received. Id have to design it though, that's why I was hoping there is something already out there.

Motorsports-X said:

There should be a pretty clear "signal" when the pressure spikes that can trigger the valve. I think it may be possible to use some sort of latch that causes a spring loaded valve to close once this signal is received. Id have to design it though, that's why I was hoping there is something already out there.

Click to expand...

I still don't get it why spring-loaded one-way valve doesn't work then? or does it?

i dont think a one way valve would close as long as there is still pressure applied.

Motorsports-X said:

i dont think a one way valve would close as long as there is still pressure applied.

Click to expand...

If there is no flow --> no pressure differential over the valve inlet and outlet--> even tiny spring can close the one way valve.

The inlet and outlet are both on the left. the "plate" is on the right.

Picture a cylinder 4 inches long layed horizontally. dead in the middle is a 1/4" hole. both ends have a cap. the left end cap has a 1/4 outlet hole. on the right side of the inlet hole (inside the cylinder) is the "plate" connected to the stem that seals the outlet. (so the stem is 3.5 inches long or so)

So both the inlet and outlet are to the left. even with no flow, there is still pressure forcing the plate to the right, (and the stem open away from the hole)

when the flow stops, (less flow more pressure) you get a spike that should signal the plate enough to trigger some sort of mechanism that closes the outlet.

sounds like the FMC iritrol valve for sprinkler systems. Timer sends pulse signal to control one electric valve then the pulse cascades down the line. Allows you to water down a golf course with only one electric valve and wires but many separate zone valves.
Bill D

an electric/hydraulic/pneumatic actuator would make it very easy but would require controls and timings. there is lots of variables here so the only way to really make it work is for it to happen automatically, mechanically. Also, I dont have room for it.