Surface supply diving allows the diver to use air from the water surface to assist him. There are many procedures that can be used to supply air from the surface, which is similar to 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 Diver's umbilical is the primary connection between the diver and the surface supply diving system. It carries the primary oxygen from the surface to the divers' apparatus. You can attach the umbilical directly to the diver or via a bell panel.
The umbilical connects the diving mask to the surface and contains many devices that help divers remain safe and comfortable in water. Some of these devices could include a communications cable, a pneumofathometer and a hot water suit. This allows divers to keep track of their depths, and also provides additional air for emergency situations.
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. Whether the diver is conscious or not, the pressure of the air can vary considerably during a dive. This can increase the work of breathing, as well as the hydrostatic pressure and cracking pressure. These changes are not harmful to oxygen delivery to your lungs. By raising the pressure, the diver can make their respiratory system more efficient in removing carbon dioxide. This improves the quality of their respiration.
Divers usually breathe from the demand valve, while the main air supply is controlled by a regulator. The regulator is normally fitted with a single tube and 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
A pressurized environment is required for surface supply diving. There are several ways to do this, including a saturation system or a "saturation spread." 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 can be used most often offshore, near production or drilling platforms, and within the context of salvage operations. You must be precise in your positioning to perform this type dive. This can usually be done from a specialist diving support vessel or any other vessel that is suitable. It is important to have reliable systems for dynamic positioning.
Diver's fitness-to dive exam
A comprehensive fitness-to dive examination must be completed before a diver can participate 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 define the standards for medical examination. Some agencies require that a physician examine the diver, while others view the examination as largely a personal responsibility. These standards are almost always the same between different agencies. These standards are often based upon those for professional divers. However they can be adjusted slightly to decrease the likelihood of diving-related medical problems.
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 controls the gas supply for surface supply diving. As a result, the pressure of the air in the tank does not automatically adjust as the depth decreases. Some surface supply diving demand Helms may have an additional feature called a “dial-a–breath” system which allows the diver or divers to adjust the level of gas in their tank.
Apart from the tank, divers will also require a set of voice communication equipment to communicate with the surface. These devices are connected by an umbilical cables to the diver's helmet or full-face face mask. Before diving, ensure that the cable is in good condition.