Surface supply diving allows the diver to use air from the water surface to assist him. The standard procedures for surface supply diving are very similar to those used in scuba diving. Although many of these procedures can be used by all divers, others are only applicable to certain equipment and dive tasks. For those new to surface supply diving, or who have never been certified to dive without their scuba gear, these procedures might be slightly different.
Diver's umbilical
The primary connection between the diving system and the diver is the umbilical. It carries the primary oxygen from the surface to the divers' apparatus. It can be connected directly to the diver, or via a bell-panel attachment.
The umbilical connects diving mask to the top and includes a number of devices to ensure divers are comfortable and safe. Some of these devices could include a communications cable, a pneumofathometer and a hot water suit. These components enable divers to monitor depth and provide air in emergency situations.
Diver's demand valve
The Diver's Demand Valve is designed to increase surface supply diving air pressure. The demand valve can make a diver breathe slower and deeper than normal. The air pressure can vary a lot during diving, whether the diver is aware of it or not. This can increase both the work of breathing and the hydrostatic pressure. These changes do not affect the oxygen supply to the lungs. By increasing the pressure, the diver's respiratory system can be more efficient at removing carbon dioxide from the air, and this improves the quality of their breathing.
Divers normally inhale via the demand valve. However, the regulator controls the main air supply. The regulator is usually fitted with a single hose and is held by the diver's mouthpiece. If the diver is using a dual-hose regulator the demand valve is located inside the regulator. It attaches to either the cylinder valve outlet or the manifold outlet. When the diver takes in air, the demand valve will send gas to the remote jawpiece at ambient pressure.
Saturation spread
It is necessary to have a pressure environment in order to surface supply dive. You have two options: a saturation system, or a "saturation spreading". Saturation diving involves diving under the pressure of a saturation accommodation. The divers then return to the surface with a mixture made up of helium and oxygen.
Saturation diving is most commonly used offshore, near production and drilling platforms, and in the context of salvage operations. It is crucial to be precise during a dive for this type of diving. This is usually done using a special diving support vessel or other suitable vessel. However, dynamic positioning is essential and requires reliable equipment.
Diver's fitness for diving
Divers must pass a complete fitness-to-dive exam before participating in surface supply diving. An AMED (diver's medical examiner) will perform this exam. They will also assess any other health conditions that may pose a threat to their diving abilities. The exam is valid for 12 months, and must be renewed each year. The diver must also pass a fitness test at renewal.
The dive certification agencies set the standards for medical examination. Some agencies require that a physician examine the diver, while others view the examination as largely a personal responsibility. However, these standards are usually similar between different agencies. These standards often reflect those of professional divers. However these standards may be slightly relaxed to reduce the incidences of diving-related conditions.
Diver's equipment
The equipment for surface supply diving doesn't differ significantly from the equipment used by deep divers. The major difference is the gas used. In surface supply diving the gas used is set at the gas panel. Therefore, the pressure in the tank doesn't automatically decrease with depth. Some surface supply diving helmets come with an extra feature called a dial-a-breath system, which allows the diver to adjust their tank's gas levels.
Divers also require a set if voice communication devices to communicate with the surfaces. An umbilical cable connects these devices to the helmet or full-face mask of the diver. Before a dive, the diver should check the cable for sound quality and function.