Know your gear : the regulator

Shared by Ksso on February 12, 2011 in Technique

The regulator is a key piece of the diver's gear. Like my instructors used to repeat relentlessly "Air is life", and the regulator bring breathable air to your mouth. The main function of a regulator is fairly simple:


  1. Adjust the air pressure (from the tank pressure to the environment  pressure)

  2. Enable inhale and exhale of the air


The classic regulator is composed of 2 stages. The first stage mounts right on the tank and will adapt the tank's air pressure to the environment. Standard 1st stage regulators also include a high-pressure plug to connect to the manometer and get a direct reading to the tank's pressure (and letting you know hom much air you've got left).

A 1st stage regulator works as described in the scheme below : Water and low pressure air fight agains a membrane. On the upper side of the membrane, the high-pressure air can move to the low pressure area as long as the low pressure area's pressure is lower than the water pressure. As soon as this condition is not met anymore, the low pressure air will push on the membrane, pulling the piston and locking up the high-pressure air... until pressure in the low-pressure air section drops.



In the diver's mouth, the second stage regulator functions in a similar way. When inhaling, the pressure in the mouth drops, thus letting air flow from the low-pressur air to the mouth until balance is restored and piston locks the air in the low pressure tube again.

You may have read while looking to buy new gear that some regulators are better suited for ice diving than others. That's because of the adiabatic expansion of gas. If you recall some college-grade thermo dynamics we have for a perfect gas :
P*V = n*R*T
Which means that since pressure is dropping from high to low, temperature needs to drop likewise. As a consequence if your diving in icy water, i.e under than 5ºC, ice may form inside the regulator thus preventing the valve to close and letting high-pressure air out. Some regulators using teflon coating and preferring plastics to metal are thus better suited for ice-diving.

Also it's important to note that you should revise your regulator yearly. Moisture can cause the internals to grip and may lead to deadly consequences. Revision can be expensive (~100 eur) so think carefully before buying your gear, if you're a recreational diver doing a couple dives a year, renting may be a better option.

If you want to dig this subject even deeper , check out the wikipedia page

About the author:

#
  • us Ksso

  • # CMAS 3* VDST / N4
  • Qualifications:

    PADI Ice Diver, CMAS Nitrox 1, Photography

  • Dived in: French Polynesia, Honduras, Jamaica, Netherlands Antilles, United States, Mexico, Portugal, Spain, Dominican Republic, Egypt, Thailand, Greece, Cyprus, France, Indonesia

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