How to exhange an object from airlock into water?

[originator]

hello

i am trying to design a system that will allow me to send an object down an airshaft, and then have that object enter the water without water rushing back in.

for the sake of an easy to understand word picture:

an airshaft is submerged into a body of water for approxiamately 20 feet. at the end of the airshaft, the shaft is sealed so that water cannot rush back into it. imagine that i want to take a 55 gallon drum, lower it into the airshaft, have it pass through a watertight seal into the water and not have any water escape back into the airshaft. i there a place i can look to research how this is done? i can easily design a system that will create an airlock around the drum, release it into the water, then evacuate the water in the airlock, but i want a system whereas there is no airlock, so that the motion of the 55 gallon container does not stop. thanks for any advice on where to start looking.

 

[arto]

how about pressurize the tube to match the head of water??

 

[originator]

that is a great idea in the right circumstance, i know that my info was limited.

since my system will required multiple entries of containers into the airshaft to be injected into the water, using pressure will require that there is an air lock of sorts at the top to prevent the water from rushing in at the bottom of the shaft. with limited sources of examples, the best i can suggest is that i need a flexible tube resembling a sphincter for a seal. the container can have a cone shaped attachment at both ends, so that the seal expands as the container travels through, then closes on its exit. with this system there should be some leakage at greater depths, but a minimal leakage might be manageable with a sump. i have never seen such a device, i think it would be made of rubber if it existed. thank for any suggestions.

 

[IRstuff]

The other option is to let the water in.

Your barrel apparently needs to be able to go into the water in any case; so it just travels 20 extra feet in water.

TTFN

 

[StephenA]

I agree with IRstuff, but just so we understand the problem better, what is the still water level outside the shaft?

StephenA

 

[ssreese1500]

what if you put a one way valve on the skin of the airshaft. it would need a spring pressure less than the watertight seal, and would need to be near the surface to minimize the effect of 20 feet of waterhead. It would work if your watertight seal really is that. The drum entering the water would displace the water out the one way valve and would equalize once the drum was submerged. of course, if it doesnt matter if water gets back in, just drill a hole instead of using the one way valve

 

[oxilume]

Originator,

The "sphincter for a seal" is commonly referred to as a pinch valve.

see

http://www.redvalve.com

Red Valve manufactures very large pinch valves. When high pressure air or water is introduced in the annulus between the rubber sleeve and the housing it causes the rubber sleeve to contract (identical to a sphincter). The rubber sleeve will contract around a barrel.

Todd

http://www.oxilume.com

Todd

http://www.oxilume.com

 

[originator]

thanks Todd, that is the idea i am looking for. i had already started designing a system with air that compresses a rubber valve, that is a coincidence.