Ask the tech what the cracking effort is of the reg. Due to the case geometry of the Proton, the setting should be between 1.0-1.3 inches of water. Also, ask them how much the intermediate pressure is dropping when the purge valve is depressed. It should not drop more than 10-12psi while purging. The static intermediate pressure should be between 138-150psi.
One quick test that you can perform using a cylinder is as follows. Put the reg on the valve, and prior to pressurizing the reg lightly shake the second stage. Listen for a clicking or tapping sound. Next, pressurize the reg and repeat the light shaking motion. While the reg is unpressurized you should not hear the sound. After pressurization, you should be able to hear the audible clicking. If the clicking occurs while unpressurized then the lever is set incorrectly, and can be the cause of excessive inhalation effort. This simple screening test only applies to a primary second stage. The AAS is typically set to a cracking effort of 1.2-1.6" to reduce the chance of leakage. An AAS might have the audible clicking while unpressurized.
When I service the Proton regs, I set the primary to 1.1", and the AAS to 1.3" This makes certain that the primary does not free flow in the worst case position, that being face down parallel to the surface. Due to the case geometry this allows the reg to have a "true" cracking effort of around 0.5" in a typical, slightly head up, swimming position.
Judging a reg's performance by inhaling from it at the surface is much like judging a car's performance potential by listening to the engine being revved at a street light. Make a dive with it, and then discuss it with the tech.
Greg Barlow
