A scuba regulator has several functions, all of which allow a diver to breathe underwater. The first stage attaches to your scuba cylinder and that reduces the pressure from high to intermediate. The second stage reduces the pressure further from intermediate to ambient. That means that the work of breathing is almost, but not quite, as easy as taking a breath of air on land.
Diving regulator first stages can be either piston or diaphragm. Either design may be equally as good and equally as sensitive to the diver’s inhalation needs except under conditions where high flow is required. In that case the piston first stage quite often delivers more air than the diaphragm first stage.
All modern diaphragm first stages are balanced so that the intermediate pressure does not change with tank pressure or depth. The diver will get a constant work of breathing regardless of how low the diver’s cylinder pressure is or how deep the diver may be. This means the diver must monitor their pressure gauge (SPG) regularly so they don’t run out of air.
The Piston regulator may be balanced or unbalanced. Unbalanced means the work of breathing will increase as the diver’s air supply reduces or the diver goes deeper.
Some positives for the diaphragm regulators are:
1/ Good cold-water reliability: Most of the working parts of a diaphragm first stage are sealed from water, making the regulator less likely to free-flow.
2/ Easier to keep clean: The working parts of a diaphragm first stage are sealed from water, so a diaphragm first stage is easier to keep clean and free of salt water corrosion than a piston first stage.
Some positives for the piston regulators are:
1/ Less moving parts to replace during servicing: most piston first stages are very simple to service.
2/ The potential air flow is higher in a high-performance piston first stage.
Some more tips: Look for the main brand types where parts are available and service technicians are familiar with them. There are a few features that will make your dive a little bit easier. Venturi assist and adjustable inhalation effort allows you to adjust inhalation effort which is great for demanding dive conditions. Look for a lighter second stage and comfortable mouth piece, they will reduce jaw fatigue.
It must be remembered that all good quality first stages provide an excellent breathing performance for recreational diving. If you are intending to become a Tech Diver then you need to take professional advice on regulator selection.
What is our final advice – ‘buy the best regulator you can afford, one that is most suited to the type of diving you are doing’. Call in to NZ Sea Adventures and ask for our advice and assistance with your regulator selection. 04 233-8238.