UK specs are that "Any gas with a percentage of oxygen greater than 23% is classed as Oxygen" hence the gauge is marked "Oxygen" and sometimes the words "USE NO OIL" is printed on the dial.
The manufactured spec is BS1780 class 1 (or the EU equiv) with a small bore restrictor inlet fitting. Also an over protection device, usually a water proof blow out plug. To cover for shock resistance gauges are normally liquid filled. For Oxygen this is Halocarbon liquid (and is stated on the gauge if used).
On high quality gauges, the movement is shock resistant by using an Inconel spring movement or a beryllium copper "bourdon tube" with a geared quadrant and pinion. This takes away the need for a liquid dampning fill. However for diving a heaver case is required to the depth rating for air filled cases.
For compressed Air use the liquid is normally Glycerin, or silicone liquid. Both these liquid dampners are a fuel, and are NEVER used in oxygen service.
The high pressure hose this is normally to SAE 100R7 or R8 specification and is also fitted with a restrictor at the demand valve, 7/16UNF end.
Cleaning is normally with a suitable solvent until the inspected solvent fluid once evapourated on a glass dish remains uncontaminated both by particulate and by U/V Light. The hose is then flushed with either white spot Nitrogen or oil free air (2 micron Filter) at 0.5 bar pressure until dry. No hose is assembled to the gauge for 24 hours, for off gassing.
Basic advise is look for the "Oxygen" labels on the gauge and for the restrictors in the hose.
In US the spec is ASME B40.1 for the gauge movement and for sports SCUBA hoses it is a odd "DEMA 105" spec (any one have a new copy of this?) Also for AIR the US make a statemant like "This gauge is filled with Glycerin. Be sure Glycerin can safely mix with the process fluid in case of leaks". This covers the "Thermic Lance" properties of high pressure Oxygen gauge fires.
The manufactured spec is BS1780 class 1 (or the EU equiv) with a small bore restrictor inlet fitting. Also an over protection device, usually a water proof blow out plug. To cover for shock resistance gauges are normally liquid filled. For Oxygen this is Halocarbon liquid (and is stated on the gauge if used).
On high quality gauges, the movement is shock resistant by using an Inconel spring movement or a beryllium copper "bourdon tube" with a geared quadrant and pinion. This takes away the need for a liquid dampning fill. However for diving a heaver case is required to the depth rating for air filled cases.
For compressed Air use the liquid is normally Glycerin, or silicone liquid. Both these liquid dampners are a fuel, and are NEVER used in oxygen service.
The high pressure hose this is normally to SAE 100R7 or R8 specification and is also fitted with a restrictor at the demand valve, 7/16UNF end.
Cleaning is normally with a suitable solvent until the inspected solvent fluid once evapourated on a glass dish remains uncontaminated both by particulate and by U/V Light. The hose is then flushed with either white spot Nitrogen or oil free air (2 micron Filter) at 0.5 bar pressure until dry. No hose is assembled to the gauge for 24 hours, for off gassing.
Basic advise is look for the "Oxygen" labels on the gauge and for the restrictors in the hose.
In US the spec is ASME B40.1 for the gauge movement and for sports SCUBA hoses it is a odd "DEMA 105" spec (any one have a new copy of this?) Also for AIR the US make a statemant like "This gauge is filled with Glycerin. Be sure Glycerin can safely mix with the process fluid in case of leaks". This covers the "Thermic Lance" properties of high pressure Oxygen gauge fires.
