Re: Regulating air supply

[Dale Fredenberg <dalef@terracom.net>]

> Buoyancy control is something that I'd love to hear some discussion about
> too...


Miller Fluid power sells a valve that might work for buoyancy control. Here is the discription form their 
catalog.
 
DESCRIPTION: The Liquid Level Sensor Kit consists of a flow control and a sensitive amplifier (1/2000) mounted 
on a double subplate, which will provide a signal to another component or device when the fluid level in a 
container reaches the opening of an air sensing tube. 

OPERATION: Air is allowed to leak out of a sensing tube. The rate is set by the flow control to permit the 
fastest response time of the amplifier without causing bubbles in the fluid being contacted. An adjustable 
flow control is used to control the air flow rate based upon the internal diameter of the sensing tube being 
used. When the fluid in the container blocks the opening of the sensing tube, the pressure increase in the 
line signals the sensitive amplifier to open or close (depending on whether it is the positive or negative 
type), thereby signaling another valve or device. NOTE:To avoid the effects of capillary action of the fluid, 
we recommend a minimum internal diameter of the sensing tube of at least 1/4" or 6 m.m.

Use this with a air pilot operated valve and you should be able to maintain a constant air bubble as you 
descend.


Dale