This is our Hollis Regulator Section. Johns Quick Tip’s: First Stages Piston Un-Balanced This is the simplest of first stages. They are commonly seen on argon and oxygen systems. They are not ideal but they are affordable and your average person can rebuild them themselves. Piston Balanced or Diaphragm I can only give you my opinion here. I am a diaphragm guy. They are easier to work on and easier to adjust the intermediate pressure. The one thing you here from piston guys is that the piston reg flows more air though the first stage. This is true but you also have to be realistic here. A diaphragm will do about 50 to 60 cubic foot a minute though a port. A piston reg will do about 70 to maybe 80 so in the real sense, yes a piston is higher performance. So if you plan on breathing an aluminum 80 in one minute you are going to need a piston reg J Oh crap I forgot that all high performance second stages limit air flow so I guess have that piston reg really only does so much. Seriously though buy a diaphragm or a piston reg if you are happy that is all that matters and either reg will give you years of service.
Johns Quick Tip’s: Second Stages
Again, I can only give my opinion here based on over a decade of selling dive gear. Do not waste your money a cheap second stage. Buy a good second. There are a many things that a good second stage has over a cheap one and yes there are many vendors that make their regs look just like the better ones. What you usually find out is the reg inhalation diaphragms, levers, and seat retainers are not Teflon coated. The diaphragms are not high quality silicone, etc, etc. Inhalation resistance knobs This is the knob that you see on the side of a regulator. To get a reg to breath the best possible the seat and the orifice have to be in the lightest of contact. This allows for the lowest possible cracking pressure. The problem with this is seats wear; there is current underwater and numerous other things that can make a reg dribble air. The knob is there to allow a little tension via a spring to be put on the lever and seat to make the breathing resistance a little harder. If you do not have this knob the regs will need to be set with a little more cracking pressure resistance. Venturi This confuses more people than you can image. To put it in simple terms most people know that airplanes fly do to Bernoulli’s principle. What this means is air that goes over both side of the wing will move faster to over the large top then the bottom. This is basically what they are dong with a venturi. The air has to move quicker around it which makes the air shoot quicker into your mouth. You really notice this the deeper you go. To all Scientists: Now all you scientist out there please remember I am a dive center owner not a scientist if you have a better explanation that the lay person can understand please let me know I would love to put it up. If it requires a chart or a graph or a small tree to print out don’t bother.