page_title: Surface-supplied diving
section_title: Gas panel
hierarchical_section_title: Surface-supplied diving / Breathing gas supply / Gas panel
caption_attribution_description: English: Gas panel for surface supplied diving: Schematic diagram for one diver showing main and reserve gas inlets, breathing gas supply to the diving helmet and pneumofathometer line for depth monitoring:PG: pneumofathometer gaugeOPV: overpressure valvePS: pneumo snubberPSV: pneumo supply valveDSV: diver supply valveMP: manifold pressureRSV: reserve supply valveRP: reserve pressureMSV: main supply valveSP: supply pressureRGS: reserve gas supplyMGS: main gas supplyUP: umbilical pneumo hoseUB: umbilical breathing gas hoseDP: depth measured by pneumofathometer
context_page_description: Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scuba diving, where the diver's breathing equipment is completely self-contained and there is no link to the surface. The primary advantages of conventional surface supplied diving are lower risk of drowning and considerably larger breathing gas supply than scuba, allowing longer working periods and safer decompression. Disadvantages are the absolute limitation on diver mobility imposed by the length of the umbilical, encumbrance by the umbilical, and high logistical and equipment costs compared with scuba. The disadvantages restrict use of this mode of diving to applications where the diver operates within a small area, which is common in commercial diving work.
context_section_description: A gas panel or gas manifold is the control equipment for supplying the breathing gas to the divers. Primary and reserve gas is supplied to the panel through shutoff valves from a low-pressure compressor or high-pressure storage cylinders ("bombs", "bundles", "quads", or "kellys"). The gas pressure may be controlled at the panel by an industrial pressure regulator, or it may already be regulated closer to the source (at the compressor, or at the storage cylinder outlet). The supply gas pressure is monitored on a gauge at the panel, and an over-pressure valve is fitted in case the supply pressure is too high. The gas panel may be operated by the diving supervisor if the breathing gas is air or a fixed ratio premix, but if the composition must be controlled or monitored during the dive it is usual for a dedicated gas panel operator, or "gas man" to do this work.
  There is a set of valves and gauges for each diver to be supplied from the panel. These include:
  A main supply valve with non-return valve, which supplies gas to the main gas supply hose of the umbilical. This is usually a quarter-turn valve, as it must be quick to operate and obvious whether it is open or closed.
  A pneumofathometer supply valve, which supplies gas to the pneumofathometer for the diver. This valve is usually near the main supply valve but with a different handle. It is usually a needle type valve as it must be finely adjustable, but it must also be large enough to allow a fairly high flow rate, as the air may be used as an alternative breathing air source, or to fill small lift bags.
  A pneumofathometer gauge is connected to the pneumo line. This is a high resolution pressure gauge calibrated in feet sea water (fsw) and/or metres sea water (msw). and is used to measure the depth of the diver by allowing air to flow through the pneumo hose and out the end attached to the diver. When the air supply is shut off, and the flow stops, the gauge indicates the pressure at the open end at the diver.
  Each pneumofathometer gauge has an overpressure valve to protect it against gas supply at higher pressure than it is designed to take. This is essential as the main supply pressure is significantly higher than the maximum depth pressure on the pneumo gauge. There is also often a snubbing valve or orifice between the pneumo line and the gauge to restrict flow into the gauge and ensure that the overpressure valve can adequately relieve the pressure.
  Some gas panels have a separate supply gauge for each diver downstream of the supply valve, but this is not standard practice.
  The gas panel may be fairly large and mounted on a board for convenience of use, or may be compact and mounted inside a portable box, for ease of transport. Gas panels are usually for one, two or three divers. In some countries, or under some codes of practice, the surface standby diver must be supplied from a separate panel to the working diver/s.
  A wet or closed bell will be fitted with a bell gas panel to supply gas to the divers' excursion umbilicals. The bell gas panel is supplied with primary gas from the surface via a bell umbilical, and on-board emergency gas from high-pressure storage cylinders mounted on the frame of the bell.
caption: Surface supplied diving gas panel for one diver: PG: pneumofathometer gaugeOPV: overpressure valvePS: pneumo snubberPSV: pneumo supply valveDSV: diver supply valveMP: manifold pressureRSV: reserve supply valveRP: reserve pressureMSV: main supply valveSP: supply pressureRGS: reserve gas supplyMGS: main gas supplyUP: umbilical pneumo hoseUB: umbilical breathing gas hoseDP: depth measured by pneumofathometer
exif: {}