page_title: Dry suit
section_title: Exhaust valves
hierarchical_section_title: Dry suit / Components / Accessories / Exhaust valves
caption_attribution_description: English: Apeks dry suit auto dump valve on O'Three neoprene suit
context_page_description: A dry suit or drysuit provides the wearer with environmental protection by way of thermal insulation and exclusion of water, and is worn by divers, boaters, water sports enthusiasts, and others who work or play in or near cold or contaminated water. A dry suit normally protects the whole body except the head, hands, and possibly the feet. In hazmat configurations, however, all of these are covered as well.
  The main difference between dry suits and wetsuits is that dry suits are designed to prevent water from entering. This generally allows better insulation making them more suitable for use in cold water. Dry suits can be uncomfortably hot in warm or hot air, and are typically more expensive and more complex to don. For divers, they add some degree of operational complexity as the suit must be inflated and deflated with changes in depth in order to minimize "squeeze" on descent or uncontrolled rapid ascent due to excessive buoyancy.
  Dry suits provide passive thermal protection: They insulate against heat transfer to the environment.
context_section_description: The exhaust valve allows the diver to vent expanding gas from the suit on ascent in order to maintain buoyancy control in the same way that a buoyancy compensator must be vented on ascent to avoid an uncontrolled ascent, missed decompression stops, decompression sickness, arterial gas embolism or pulmonary barotrauma. The manual exhaust vent may incorporate an automatic, adjustable exhaust or supplement a separate automatic over-pressure dump valve on the shoulder.  Automatic valves are pre-set and in most situations can be left at this setting throughout the dive. Configurations differ but automatic vents are generally at the left shoulder and manual vents at the wrist. Environmentally sealed suits used for diving in contaminated water have a watertight seal to the helmet, rely on the helmet exhaust valve to release air from the suit, and may not have a separate exhaust valve on the suit itself. This is common for free-flow helmets and was part of the standard diving dress system. Older, now obsolete, dry suits had no dedicated vents; venting was achieved by raising an arm and lifting one of the wrist seals or placing a finger in the neck seal.
  Surface dry suits do not normally have exhaust valves, but the wearer may vent excess air by crouching down and hugging the legs while slipping a finger under the neck seal.
caption: Auto dump valve on neoprene suit
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