The task of a first stage regulator is quite simple: reduce high pressure air coming from the tank to a consistent intermediate pressure. They are generally divided into PISTON and DIAPHRAGM categories, depending on the mechanism used to control the valve, allowing air to flow to the second stage. Due to their design and their particular advantages, each of them have become the favourites of different groups in the diving community. First stages can be further classified between CLASSIC DOWNSTREAM and BALANCED, affecting function and performance of the first stage related to pressure changes in the tank.
THE PISTON TECHNOLOGY
The general advantage of a piston-based first stage lies in its reliability and reduced maintenance requirements, due to an effective but simpler mechanism with less moving parts. More importantly, no other design can reach the high air delivery rate of a balanced piston controlled first stage.
Air balanced flow-through piston
First stages with air balanced pistons deliver significantly more air to the second stage than any other first stage, while their performance is totally unaffected by the changing tank pressure. A balanced piston allows the use of lighter and more sensitive components, resulting in ultra fast breathing response, instant delivery of air on demand and extra high air flow, especially in low tank pressure ranges. The tired diver benefits from of a smoother breathing regulator during the ascent or deco stop. Balanced piston first stages are the first choice of demanding sport divers and professionals. A balanced piston performs equally in both warm and cold water environments. The SCUBAPRO MK25 first stage uses this technology.
Classic downstream piston
This is the best example of bulletproof reliability and trouble-free, minimal maintenance regulators. The conventional downstream piston configuration is the simplest mechanism that exists to control the pressure drop from a tank to feed the 2nd stage. The classic downstream valve is the first choice of diving centres and rental facilities worldwide for warm and moderate water temperatures. Our MK2 Plus features this technology.
THE DIAPHRAGM TECHNOLOGY
Diaphragm-based first stages are environmentally sealed so that water cannot enter the inner mechanism. Bearing in mind that regulators generate temperatures up to minus 30 °C due to the incredibly fast moving air and the high pressures involved, it is imperative that sensitive moving metal parts avoid contact with extremely cold water.
Therefore, diaphragm first stages have been the favored choice of cold-water divers and those working in contaminated or muddy water.
All our diaphragm first stages feature a balanced technology and are packed with patented features resulting in ultra fast flow to the second stage upon request and a fantastic overall performance.
The balanced diaphragm technology provides consistent performance at all cylinder pressures, at any depth and optimises the second stage performance, thus allowing for effortless breathing.
Our MK17 diaphragm first stage features a dry balancing chamber so that the water cannot enter the first stage, this means it's resistance to freezing is unmatched even in extremely cold waters.
Our MK11 diaphragm first stage has the same structure as MK17 but without a dry chamber and it is the perfect choice for the recreational diver who wants the advantage of a diaphragm fisrt stage for use in temperate waters.