Using Dry Space as Pressure Tank

[redboat219]

Absolutely correct.

[He Who Shall Not Be Named]

So I guess you'll need a dedicated air tank for this to work. = (

No. YOU'LL need a dedicated air tank for your version of a ballast sub-system to work.

Rotsa Ruck!

David
Been There, Done That, Got The T-Shirt!

[redboat219]

So I guess you'll need a dedicated air tank for this to work. One could use those stainless steel float valve balls like the RCABS-R boys use or those stainless steel sphere used as toppings for railings as a pressure tank. A 2.5 inch sphere as a a internal volume of 130cc.

[He Who Shall Not Be Named]

The SD's two internal bulkheads will hold up fine. The motor-bulkhead and forward bulkhead will pop off. All of the MSD's bulkheads/unions will pop off.

David

[redboat219]

This is another take on using the mini low pressure blower pump as an air compressor.

In Mr. Merriman's SAS/MSD air at atmospheric pressure inside the dry space is used to partially/fully blow the ballast tank surfacing the boat. Negative pressure inside the SD is then relieved through the snorkel when the sail is clear.

Would it be possible to pressurized the air inside the dry space and use it to blow the ballast tank? I'm not talking of very high pressure here. To displace water out of the ballast tank at depth of 1 meter just takes about 16 psi (1 atm) of air pressure. Just above the limit of little air pump employed as a LPB.

Pre-deployment, the dry space is pressurized to about 15 psi by the air compressor ( LPB pump). Diving is done through the usual vent valve. To surface, the boat is brought up to a depth of 1 m. Air ( now pressurized) inside the the dry space (using a servo operated valve in the bulkhead) blows the ballast tank clear. At the surface the air compressor is run to repressurize the dry space ready for the next dive.

Question is, can the SD bulkheads seals handle the increase in internal pressure? Will they pop out? I'm sure this won't be a problem with other wtc that use bolts to hold the endcaps firmly in place but I've seen wtc with water pumps/ bags ballast system that use traditional o-ring sealed bulkheads with no problems.