The different types of valves used in a dry suit are described to guide in divers’ selection. Tips on drysuit diving are also offered including pre-dive inspections and techniques on how to solve common dive problems involved in dry-suit diving.

This article will overview the different types of valves and provide some useful information on how to drysuit dive with ease and safety.

Listening to drysuit salespeople, it might sound like there are a lot of mechanical parts on a drysuit. In fact drysuit valves are pretty simple. Inlet valves let compressed air into the suit from a scuba cylinder and exhaust or outlet valves vent air from the suit. Valves that sound like body parts, such as ankle valves, wrist valves, etc. are exhaust valves named for their location on the suit. Most drysuit exhaust valves are automatic, meaning that when the valves are at the highest point they will vent air when there is sufficient force to compress the spring in the valve. There are also manual, push to dump valves.


Apeks valves are manufactured in Britain. Made of a sturdy, injection molded plastic material, the Apeks is known as a plug valve. It has a large center button that requires five pounds of pressure to operate and can easily be pushed by a gloved hand. The maximum exhaust flow rate for an Apeks valve is almost six cubic feet of air per minute.

Air enters the suit from a low pressure inflator hose, usually supplied with the suit. It is a standard hose fitting with a sliding outer sleeve but has a smaller orifice, slowing the amount of air blown into the suit. Other low pressure inflators will fit on the connection but may have a larger orifice, which will inflate a suit too rapidly.

This valve is easy to disassemble and clean. It has a back pressure spring so you can pre-set the opening pressure. The springs and assembly screws are stainless steel for longer service in saltwater. The amount of air a suit will hold before it automatically dumps can be adjusted by turning the head of the valve, which adjusts the back pressure setting. Turning the valve in, or clockwise, will increase the back pressure, causing the suit to trap more air. Turning the valve out, or counterclockwise, makes it easier for the valve to work and vents air sooner. The valve top turns 360 degrees, from wide open to minimum exhaust.

The part of an Apeks valve inside the suit features air intake holes on its sides, rather than on the back. When a diver pushes the valve, it tends to press against the undergarments or the diver’s body. Because the intake holes are on the sides, the valve opening does not get blocked. Apeks valves have been used on drysuits distributed by Typhoon and Parkway.


GSD valves are made (by an Italian manufacturer) of chromed brass and injection molded plastic. GSD inlet valves are pilot valves. This means that airflow speed increases as the volume increases. One drawback to this type of valve is that any foreign matter will cause it to jam shut.

GSD inflator valves have large buttons and require only three pounds of pressure to operate. The maximum flow rate is about 5.5 cubic feet of air per minute.

GSD exhaust valves come in two styles, automatic and push to dump. The automatic valves operate like the Apeks valve. GSD automatic valves look like the company’s push to dump valves. However, the automatic valves have a higher profile and a textured ring with directional arrows for adjusting the exhaust setting. DUI uses GSD valves on its drysuits.


Poseidon valves are made in Sweden and first appeared on the Unisuit. They are currently also used on Parkway suits. Poseidon has a unique low pressure inflation hose connector that only attaches to a Poseidon valve. It is made of chromed brass, plastic and stainless steel. Workhorses, the valves are sturdy and offer some of the highest flow rates available. To start the air flowing it takes about ten pounds of pressure on the button.

Poseidon exhaust valves are push to dump valves that require approximately 12 pounds of pressure. The button is recessed so it is hard to accidentally activate. These exhaust valves are made of plastic, rubber and stainless steel.


Manufactured by a Swedish company formerly known as S.I. Produkter, S.I. Tech valves were originally only found on Viking drysuits. Since 1989 S.I. Tech valves have been utilized by Viking and other suit manufacturers.

The S.I. Tech Sport inflation valve on Viking Sport drysuits is a unique design with the main parts of the valve in the low pressure hose fitting. The rest of the valve is mounted in the suit. These valves are easy to spot because of their square inflator button, mounted on the side. If the inflator hose isn’t attached to these valves, a plug has to be inserted or water will leak into the suit. The S.I. Tech Standard is an inflation valve fitted on drysuits used by professional or commercial divers.

The company’s automatic exhaust valve is made of Lexan R, takes 1.5 turns to adjust from fully open to minimum opening, requires about six pounds of pressure to operate and features high inside stand-offs that help reduce blockage from undergarments during manual operation.


Although they have a larger inflator button than Apeks, these Canadian-made valves are often confused with the Apeks because of their similar appearance and operation. Whites valves are injection molded plastic with chromed brass and stainless steel. They flow at about six cubic feet of air per minute and require approximately seven pounds of pressure to operate manually. The Whites valve is automatic and turns about three-quarters from fully open to minimum. It takes about 6.5 pounds of pressure to operate.


Each manufacturer selects a valve to install in its product. That choice is a balance of cost, availability, function and appropriateness for the suit. The ease of valve operation and reliability for your typical diving activities and personal size are points that contribute to your selection of a drysuit.


Drysuits need a little more care than wetsuits to stay in tip top condition. A little rip in neoprene may not even be noticeable on a wetsuit. It’s a big difference with a drysuit – a trickle of water seems like a deluge. For a relaxed, comfortable drysuit dive, begin your preparation at home a few days before the dive trip.

  1. Thoroughly inspect the drysuit before leaving home.
  2. Check the zipper for ease of operation and to be sure there are no missing teeth. (Even one missing tooth will flood a drysuit.)
  3. Gently bend the zipper in an arc. If you see any sharp bends, it means the zipper’s backing tape is torn and the suit may flood.
  4. Lubricate the zipper.
  5. Inspect the neck and arm seals for signs of cracking, tears or “gumminess.” Repair or replace questionable seals before diving or you are headed for a flood.
  6. Hook up the inflator hose to a scuba tank and test for smooth operation. The button should not stick open or closed. If the valve sticks, soak it in warm water, then rinse with fresh water to dissolve and remove salt crystals that may have formed and impaired operation.
  7. To test the exhaust valve, seal the suit’s arms and neck with rubber bands, then inflate the suit until it is full. Operate the valve to see that air flows freely.
  8. While you have the suit inflated, screw the exhaust valve shut and spray a solution of soapy water on the seams. Bubbles mark a leaky seam.

It only takes a few minutes to do this pre-travel suit inspection but saves a lot of grief and expense if you find a problem before donning the suit. The longer it has been since you used the suit, the more vigilant you should be in your inspection. If the suit has been stored in high temperatures or an area with high ozone pollution, there’s a greater chance you may discover deteriorated seals and a dysfunctional suit.


Here are a few hints to make gearing up more comfortable and hassle-free.

  1. Think about the air temperature and amount of work required to move gear to the dive entry point. Then decide in what order to do the tasks, i.e., put on the drysuit, then assemble and move gear or assemble gear, move it to a closer staging point, then don the drysuit.
  2. Use a lubricant on yourself or the suit seals to make donning easier. Non-perfumed talcum powder and soapy water are good for you and the suit. Perfumed “fancy” body powder contains oils or chemicals that cause latex seals to rot.
  3. Consider which side of the silicone spray debate you are on. Some say it is OK to use on seals and may even extend their life. Others say it aids deterioration and makes a suit harder to repair later, because adhesives won’t stick to silicone sprayed fabric.
  4. Take off all jewelry, including watches, earrings, bracelets, necklaces and barrettes. Jewelry eats seals!
  5. Put on your swimsuit or shorts and a T-shirt first, then your insulating undergarments. Have everything close at hand so you don’t get sand or water on your insulated boots before donning the drysuit.
  6. Sit down to don your drysuit. Put the bottom part on first, while sitting down, then stand up to work the suit over your hips. (Unisuits start just the opposite, with the neck seal first, but it is still easier to sit.)
  7. If your undergarment has thumb tabs to hold the sleeves in place, use them to avoid forearm bunching. Once you have pulled the drysuit up on your arm, release the thumb loops and tuck them far up into the sleeve, so they don’t cause a leak.
  8. Consciously think about not poking a finger through the seal material. You may need to cut your fingernails.
  9. Adjust your seals per the manufacturer’s suggestions but, in general, eliminate overlapping folds and gaps. Skin-to-seal is the surest.
  10. Neck seals are easier to pull on if you make your hair slippery. Since most people won’t soap their head, a nylon knee high pulled over your hair is an alternative.
  11. Have a buddy help you close back zippers, watching to be sure the underwear fabric is out of the way and the zipper is pulled hard against the end stop.
  12. Test the seals and valves by inflating and exhausting several bursts of air through the suit.
  13. Next, vent the excess air. Squat down and cross your arms on your chest while opening the exhaust valve. This procedure squeezes much of the air out. Remember to readjust the valve.
  14. Get help to don your BC and tank so you don’t catch your arm seals on the BC.

Now you are ready to enter the water!


Drysuit diving is like wetsuit diving, except you need to allow for the volume of air in the suit that shifts and expands. Most manufacturers recommend you take a pool training course designed to teach you the unique features of their product. It is important to learn and practice the techniques in a controlled environment under the supervision of an instructor.

The following are a few concepts to recall from your training session:

  1. Before you jump into the water from a height (boat deck), pull your suit up so it has the least possible material on the lower leg. By reducing the volume in the lower leg it is easier to kick. In general, get as much air as possible out of the suit before you begin a dive.
  2. As soon as you enter the water, pause and check for leaks. If you feel any, get out of the water and fix the problem. A little leak may get worse. A flooded suit does not fall into the category of an easy, fun, safe recreational dive.
  3. Do not dive in a leaking suit.
  4. Check your buoyancy, the same as you would if wetsuit diving. Try to achieve neutral buoyancy at the surface. If you are too light you may need to add weight. A typical drysuit takes 5 to 10 pounds of additional lead to overcome the air trapped in the suit.
  5. To start a dive, vent your buoyancy compensator of all air, then open the suit’s automatic exhaust valve and leave it open during the dive.
  6. If you feel squeeze on your lower body as you descend, push the inflator in short bursts to barely add enough air to relieve the squeeze.
  7. To adjust buoyancy at depth, use the suit valves, not your BC. For beginning drysuit divers, only control the suit at depth. Use the BC for flotation on the surface only.
  8. Resist the temptation to turn yourself into a human liftbag by inflating the suit and BC to raise a heavy article off the bottom. Use a liftbag, not your drysuit!
  9. Remember to position your body so the exhaust is at the highest point when attempting to vent air.
  10. Control your ascent by exhausting the expanding air from the suit. If you have an automatic valve, be sure it is open when the ascent begins. If you have a manual valve, have your hand on the button, ready to push. The key is to vent continuously, while ascending slowly.
  11. If you get behind on exhausting and start ascending too fast, take immediate corrective steps by checking valves, then creating more body resistance. Flare your body, sticking your fins out as in a standing position and/or by swimming horizontally.
  12. Once on the surface use your BC for flotation. An inflated drysuit frequently creates a tight neck seal and makes it hard to swim.
  13. If diving from a boat, remove your tank and weights before exiting the water. Remember to disconnect your inflator before taking the tank off. If you leave the weightbelt on, be sure the air in your suit will support you at the surface.
  14. If beach diving, take steps to keep sand out of valves and zippers by carefully choosing your undressing location.

Things happen. The best dressed and trained drysuit diver occasionally gets in a pickle. Here are some common situations and suggestions on how to get yourself out of the mess.

Problem: Water starts trickling in.

Action: Try to locate the leak. If it is pinpoint sized, you can likely continue the dive safely but damply. If it seems to be the zipper, have your buddy check to see if the zipper is pulled tight against the end stop. If the leak is substantial or increasing, there is a major failure and you should return to the surface and exit the water as quickly as practical.

Problem: Drysuit fills with water – a rare but memorable experience.

Action: When a drysuit fills with water you will probably be very negatively buoyant. The goal is to regain some positive buoyancy. First, inflate your buoyancy compensator. If this is sufficient to become slightly positive at depth, then begin swimming to the surface.

If your BC doesn’t offer enough lift for you to be positively buoyant, drop your weightbelt. Before dropping the weight, slightly deflate the BC so you have finer control of the ascent. Certain types of undergarments and drysuits are very negative when completely flooded. You may need to drop your weightbelt, fully inflate your BC and work to swim to the surface, remembering to adjust your BC during the ascent.

Once on the surface it can be extremely awkward to swim or move. Water is heavy and getting back on a boat may be nearly impossible. Unfortunately, you may need to have your buddy cut a small slit in each leg to drain water before you climb up a ladder. Try to make a neat slice, so it is easy to repair later!

Problem: Inflator valve sticks open and the drysuit continuously fills with air.

Action: First thing – disconnect the inflator hose while venting excess air through the automatic exhaust valve at the same time. If you only have a manual exhaust valve, disconnect the inflator hose first, then manually exhaust the excess air.

At depth you might be able to regain control by maximizing exhaust while the air is still rushing in through the inflator. However, you will probably not be able to continue this while ascending. Even if the exhaust valve is rated to dump at a numerical rate faster than the inflow of air, those ratings do not allow for the effect of the undergarments, your changing position in the water and straps that may restrict air movement inside the suit.

If everything goes wrong and you cannot disconnect the inflator hose, or the exhaust valve is not keeping up, then the last resort is to vent air out of a wrist or neck seal. Venting out of a seal definitely works – but be prepared to get wet.

Problem: Lint balls get stuck in the inside of the exhaust valve and it jams open or closed.

Action: Pile undergarments sometimes develop lint balls where the suit rubs against the underwear. The balls get sucked into the valve, jamming it open, so it continuously exhausts. Your suit will not hold air and you’ll probably get wet. Shift your body position so your right (non-valve side) shoulder is higher than the left (valve) shoulder and trap some air. Ascend using your BC and conclude the dive.

If the valve is automatic, try rotating it to see if you can dislodge the blockage. Operating it manually may also tweak it into working.

If the valve jams closed, so it will not exhaust, try to ascend where you can hang onto something to help control your ascent rate. An anchorline or kelp stalk will help. Also, be sure your BC is empty so it does not contribute any positive buoyancy. If there is nothing to grab, then venting through a wrist or neck seal may be the only option. You’ll get wet but that’s a preferable alternative to a rapid, uncontrolled ascent.

Problem: Help, I’m upside down and can’t get upright!

Action: First, hope you’ve worn ankle straps so your fins don’t blow off. Second, tuck your body into a ball, kick slightly and roll around into an upright position. Once upright, quickly vent the excess air from of the suit.

If you are near the bottom and feel your feet rising, kick hard toward the bottom, bend at the waist so your head is now pointing toward the surface and, when your feet contact the bottom, push off. Vent as soon as you are heads-up and in control.

If neither of these procedures works, you may be headed toward the surface feet first. Flare out like a sky diver, creating resistance and slowing your ascent. Exhale vigorously because you are likely exceeding the recommended ascent rate.


Nothing beats training and practice. Drysuits make cold water diving an enjoyable, year-round experience. But, drysuit divers need training on basic use and the fine operating points unique to their suits. Take a drysuit pool class and experience leaks, floods, open and closed valves, trapped air and the tricks of donning and doffing a suit. Use the educational environment to familiarize yourself with this outstanding piece of equipment. Drysuits are a financial and educational investment that will enhance your underwater enjoyment.


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