Surface supply diving refers to using surface air to assist the diver. There are many procedures that can be used to supply air from the surface, which is similar to scuba diving. While many of the procedures are similar for all divers, some are specific to certain equipment or diving tasks. These procedures can be slightly different for new divers or those who have never dived without scuba equipment.
Diver's umbilical
The primary connection between the diver, the surface supply diving equipment and the umbilical of the Diver is through the umbilical. It carries the primary oxygen from the surface to the divers' apparatus. The umbilical can be either directly attached to the diver, or it can be attached via a bell panel.
The umbilical connects a diving mask to the surface, and it contains a variety of devices to help divers stay safe and comfortable in the water. This could include a communication cable or a pneumofathometer. These components allow divers to monitor their depths and supply additional air in an emergency.
Diver's demand valve
The Diver’s demand valve allows for an increase in the air pressure used during surface supply diving. This pressure can cause diver to breathe faster and deeper than without the demand valve. The air pressure can vary a lot during diving, whether the diver is aware of it or not. This can increase the work of breathing, as well as the hydrostatic pressure and cracking pressure. However, these changes do not impair the oxygen delivery 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 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 supplies gas at ambient pressure to the remote mouthpiece when the diver inhales.
Saturation spread
The environment must be pressurized for surface supply diving. You have two options: a saturation system, or a "saturation spreading". Saturation diving refers to diving where divers are placed under pressure using a saturation accommodation system and then return to the surface by inhaling a mixture of helium and gas.
The majority of saturation diving is done offshore, on drilling platforms or near production, and when there are salvage operations. You must be precise in your positioning to perform this type dive. This can often be done from a specialized diving support vessel (or a vessel suitable for the occasion). Dynamic positioning is also important, but requires a reliable system.
Diver's fitness-to-dive examination
Divers must pass a complete fitness-to-dive exam before participating in surface supply diving. 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. The diver will have to pass a fitness check at 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. The standards vary between agencies but are generally the same. These standards are often based on the standards for professional divers. However, they may be slightly relaxed to decrease the incidence of diving-related medical conditions.
Diver's equipment
Equipment used for surface supply diving does not differ from equipment used by deep divers. The primary difference is the breathing gas used. The gas panel determines the gas that is supplied for surface supply diving. Because of this, the tank's pressure is not adjusted automatically when the depth drops. Some surface supply diving demand helmets have an extra feature called "dial-a breath" that allows the diver adjust the gas level in their tank.
Aside from the tank, divers also need a set of voice communication devices for communication with the surface. These devices connect to the mask or helmet of the diver using an umbilical wire. The cable should be checked for function and soundness before diving.