A word of safety advice rather than any 'trade trick'... about SPG's. Just as you are advised when on scuba to, "check your SPG often" so you should when on surface supplied eguipment. In fact it's even more important to keep a check on your bailout cylinder contents as when you begin to 'dry-up' on scuba you at least get a few tight breaths as a warning, but if you have to go on to bailout in an emergency and your bailout is empty... you are in deep sh1t
So, maintain the habit of checking your bailout contents and also check that the bailout valve on the helmet is closed - if its cracked open even slightly you may breath down your immediate back-up supply without knowin... bad karma.
Check gauge, check valve, no problems.
Berko
