AboutMike Giles Expertise I am a Master Scuba Instructor with over 6000 dives. I can answer questions on general diving techniques, diving education and diver training. I can offer suggestions on the use and selection of proper dive equipment, general maintenance of dive equipment as well as diving equipment repair. I can also offer suggestions on air conservation techniques and buoyancy control. As a dive shop owner for 17 years, I can offer suggestions on starting/running a dive business.
Experience I have been diving for 52 years, teaching diving for 47 years and owned a diving business for 17 years. I am a certified regulator repair technician for several different brands and a certified scuba cylinder inspector.
Organizations I am currently a member of the Professional Association of Diving Instructors (PADI), Divers Alert Network (DAN), International Resort and Retailer Association and the Better Business Bureau
Publications Undercurrent magazine and Divers Chapbook
Education/Credentials I am a Master Scuba Diver Trainer with 15 distinct specialty instructor ratings, Rescue Diver Instructor, Medic-First Aid Instructor and I have degrees in Chemical Engineering, Biology and Radiologic Technology.
Question Hi,I would like to ask ;
The intermediate pressure of the first stage is 140 psi (average) till the second stage. Is this pressure vary depending on the water pressure. 140 psi at the surface and 195 psi at the 100 feet or is it constant for all dept?
Thanks & regards
Hakan
Answer Hi Hakan
That's a good question and I can tell that you've already given it some thought.
You are correct in that the intermediate pressure is around 140 psi and can vary somewhat depending on the manufacturers specifications. Since this pressure is controlled only by spring compression, it is independent of the effects of water pressure. This means that the intermediate pressure will remain unchanged regardless of the depth.
That is not the case with the second stage. Second stages, as you may already know, are designed to deliver air at "ambient pressure". This means that they will compensate for the change in depth (water pressure) so as to deliver air to the diver without the need for increased breathing effort as the depth increases. This is accomplished by the diaphragm found in the second stage. On some second stages, there may be an additional adjustment which can "fine tune" this compensation to further reduce the effort of breathing at depth.
Hakan, I hope this provides the information you were looking for.
