The minimum standard for any regulator for year-round use in UK waters should be stamped with the EN250:2014 certification . This shows the unit has been tested for use at depths of up to 50m and water temperatures as low as 4 ° C .

First and second stages can be balanced or unbalanced . The former offers a constant air flow regardless of depth or tank pressure . Unbalanced

regulators may require a little more effort in the same circumstances . First stage regulators are available in DIN ( Deutsche Industrie Norm ) or yoke / a-clamp fittings . The threaded DIN is lighter in weight , offers a more secure connection and can handle up to 300 bar against the yoke ’ s 232 .

The next choice is between piston or diaphragm first stages .

The piston is of simpler design , providing a fast , efficient airflow to the second stage . However , diaphragm regulators have the added advantage of an environmental seal , which prevents water ( plus potential freezing ) and contaminants such as silt or oil reaching the inner components .

It ’ s a good idea to think about future-proofing your kit as you go . This applies not just

to regulators but across the board . In this instance , look for something with a pair of high-pressure ports . This will enable both a hose-mounted pressure gauge and a wireless transmitter to be used sideby-side . Most manufacturers ’ regulators are compatible with Nitrox up to 40 %, but if you ’ re looking to exceed this then it ’ s worth checking what ’ s available .