Free Flow – Malfunction of a Demand Regulator in Scuba Diving


Scuba diving is an exhilarating underwater adventure that offers unique experiences and encounters with marine life. To ensure a safe and enjoyable dive, it is crucial to have a reliable and functional diving equipment setup. A key component of this setup is the demand regulator, which is responsible for providing the diver with breathable air at a suitable pressure. However, malfunctions can occur with this vital equipment, one of which is known as “free flow.” This entry will cover the definition of free flow, its causes and consequences, and the steps divers can take to prevent and address this issue while underwater.


Free flow is a malfunction of a demand regulator, where the valve sticks in the open position, causing a constant rate of flow. In this situation, the regulator continuously supplies air without any input from the diver. This can lead to rapid depletion of the air supply and put the diver at risk of running out of air.


Several factors can contribute to a free flow malfunction, including:

  1. Wear and Tear: Over time, demand regulators may experience wear and tear that can cause the valve to stick in the open position. Corrosion, debris, or damaged parts can interfere with the proper functioning of the regulator.
  2. Cold Water: Diving in cold water can lead to the formation of ice crystals within the regulator, which may cause the valve to freeze open. This is particularly common when the first stage is not environmentally sealed.
  3. Improper Maintenance: Inadequate or irregular servicing can result in parts becoming worn or damaged, causing the valve to malfunction.
  4. Manufacturing Defects: In some cases, a manufacturing defect may be the cause of a free flow malfunction. It is essential to purchase high-quality diving equipment from reputable manufacturers to minimize this risk.


The primary consequence of a free flow malfunction is the rapid depletion of the diver’s air supply, which can lead to a potentially dangerous situation. If not addressed promptly, a diver may run out of air and be forced to surface quickly, increasing the risk of decompression sickness. In extreme cases, the loss of air supply can result in drowning or other serious injuries.


To minimize the risk of a free flow malfunction, divers should take the following preventative measures:

  1. Regular Maintenance: Ensure that the demand regulator is serviced regularly by a qualified technician. This should include cleaning, inspection, and replacement of any worn or damaged parts.
  2. Proper Storage: Store the regulator in a cool, dry place when not in use. Avoid exposure to extreme temperatures or direct sunlight, which can cause damage to the regulator’s components.
  3. Environmental Sealing: If diving in cold water, consider using a regulator with an environmentally sealed first stage. This can help prevent the formation of ice crystals and reduce the risk of a free flow malfunction.
  4. Quality Equipment: Purchase high-quality diving equipment from reputable manufacturers to minimize the risk of manufacturing defects.
  5. Pre-dive Checks: Conduct thorough pre-dive checks of your equipment, including inspecting the regulator for any signs of wear, damage, or debris.

Addressing Free Flow Underwater

If a free flow malfunction occurs during a dive, the following steps can be taken to address the situation:

  1. Calmly signal to your dive buddy that you are experiencing a problem with your regulator.
  2. Attempt to free the stuck valve by tapping the purge button or gently tapping the second stage on a solid surface, such as a tank or a rock.
  3. If the free flow continues, switch to your alternate air source or share air with your dive buddy using the buddy-breathing technique.
  4. Ascend slowly and safely to the surface, maintaining a safe ascent rate and performing any necessary decompression stops. Once at the surface, signal for assistance and end the dive.
  1. In the event of a free flow during a deep dive, it may be necessary to perform a controlled emergency swimming ascent (CESA) if an alternate air source or buddy is not immediately available. Remember to exhale continuously while ascending and maintain a safe ascent rate.
  2. Once back on the boat or shore, inspect the regulator to determine the cause of the malfunction. If possible, address the issue before resuming diving activities. If the problem cannot be resolved on site, seek professional assistance from a qualified technician.


Free flow is a malfunction of a demand regulator that can lead to rapid depletion of a diver’s air supply and pose significant risks to their safety. Understanding the causes, consequences, and preventative measures for this malfunction is crucial for maintaining a safe and enjoyable diving experience. By regularly maintaining equipment, investing in high-quality gear, and being prepared to address free flow issues during a dive, divers can mitigate the risks associated with this malfunction and continue to explore the underwater world with confidence.