Surface supply diving uses air from the surface to help the diver. There are many procedures that can be used to supply air from the surface, which is similar to scuba diving. Many of these procedures can be used for all divers. Some are more specific to equipment or diving tasks. These procedures may differ slightly for surface supply divers, as well as those who are not certified to use scuba gear.
Diver's umbilical
The Diver's umbilical is the primary connection between the diver and the surface supply diving system. It is responsible for carrying the primary breathing gas from surface to diver's equipment. It can be attached directly to the diver's apparatus or through a bell panel.
The umbilical connects diving mask to the top and includes a number of devices to ensure divers are comfortable and safe. The devices include a cable for communication, a thermometer, and a hot-water suit. All of these components make it possible for divers to monitor their depth and provide additional air in case of an emergency.
Diver's demand lever
The Diver's demand valve increases the pressure of surface supply diving air. The demand valve can make a diver breathe slower and deeper than normal. Whether the diver is conscious or not, the pressure of the air can vary considerably during a dive. This can increase the work required to breathe, and also the cracking pressure and hydrostatic pressure. These changes will not reduce oxygen delivery to lungs. The pressure can increase the efficiency of the diver's breathing system in removing carbon dioxide. This improves their quality of breath.
Divers inhale from the demand valve. 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 uses an dual-hose regulator, then the demand valve is attached to the cylinder outlet. The demand valve is activated when the diver breathes. It will provide gas to remote mouthpiece at ambient temperature.
Saturation spread
A pressurized environment is required for surface supply diving. You have two options: a saturation system, or a "saturation spreading". Saturation dive is when divers are put under pressure by a saturation accommodation and then returned to the surface using a helium-based gas mixture.
Saturation diving is most commonly used offshore, near production and drilling platforms, and in the context of salvage operations. For this type diving, you need to know where you are going and how you will position yourself. This is usually done using a special diving support vessel or other suitable vessel. Dynamic positioning is also important, but requires a reliable system.
Fitness-to-dive exam for divers
Before participating in surface supply diving, divers must undergo a comprehensive fitness-to-dive examination. This is done by an AMED, which will examine any underlying medical conditions that could be a problem for their ability to dive. The exam is valid for 12 months, and must be renewed each year. A fitness test will be required at the renewal.
Dive certification agencies specify the medical exam standards. While some require the medical practitioner to conduct an examination, others see it as largely the responsibility of the individual. These standards are almost always the same between different agencies. Often, these standards are based on those for professional divers, but may be relaxed slightly in order to reduce the incidence of diving-related medical conditions.
Diver's equipment
Surface supply diving equipment is very similar to deep diving equipment. The major difference is the gas used. The gas panel controls the gas supply for surface supply diving. 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.
Apart from the tank, divers will also require a set of voice communication equipment to communicate with the surface. These devices can be connected to the full-face helmet or mask by an umbilical cord. Before diving, ensure that the cable is in good condition.