Alternative diving system

Hi my darnell sub has two aerosol cans mounted in the centre watertight are connected to a pump, would it be feasable to replace the cans with some sort of air bag system?

David

Hi David,

It would be helpful if you could give some more info.

Is it an old model which you have bought? If so you may have someones take on the original Darnell system. (Air pumped from a reservoir (the cans?) into a bag.)

My view is that the bag system is OK for smaller subs but you may wish to adopt the later Sheerline system (water pumped into a pressure vessel (the cans again??)

If you have a look at the AMS website you will see a description of all the dive systems with their pros and cons.

David

Actually I have just had a look at the website and the description of the pressure tank (Sheerline) system is not very clear. (I think a diagram is missing.)

Is there any chance of fixing that, Richard?

David

Thanks David, the system as is stands just now is-
There are two aerosol cans in the centre section of the sub. Thete are two holes in the hull inderneath the cans to allow water into the chamber when the compressor pumps the air from the flood space into the aerosol cans and a switch reverses the system blowing the air stored in the cans back into the space to force the water out.
Thats how I think it works anyway lol

David

Hi David,

Sounds like you have a slightly modified Darnell.

The compressor is perhaps out of a car pump? (The original Darnell used a small oscillating steam engine.)

I don't think I would want to try to get that working. Water and compressors is an awkward and complex mixture.

Again, I don't think you would go far wrong by using the pressure tank system as used by Sheerline. The only bits needed are a pressure tank (baffled to prevent sloshing and able to stand about 3 bars) a gear pump and a pinch valve on a servo. if you have  a good budget - go for an Engel piston tank.

You will find lots of discussion and description of these items on this forum. The pressure tank is perhaps the most difficult item. I use home made ones (PVC pipe reinforced by glass fibre sheathing.) Sheerline do very nice stainless steel ones for a price!

Maybe if you go to Norwich you can talk Chris of Sheerline into giving you just a tank for a reasonable sum?!

The pump on the Sheerline website looks nice and is at a fair price. We have always liked the red plastic ones but they are not as well made as they used to be. (Talking to Chairman Nigel he thinks he has found a supplier of the original nice, French made ones.)

David