Mesh materials for oxygen operating equipments
Nickel and nickel alloys mesh are highly resistant to ignition and combustion. These materials provide good strengths with high hardness at the low temperatures.
Inconel alloys
NiFe alloys such as Inconel wire mesh material offers high ignition resistance. Alloy 718 has been widely used in the high pressure oxygen units over the decades because of its supreme structure matrix and it is less ignitable as compare to steel materials. Few Inconel alloys are used successfully at pressures about 69 MPa. Inconel grades also prevent ignition by particle impact superior to the stainless steels however it is similar at 440oC. Some Inconel alloys also offer outstanding ignition resistance caused by frictional heating.
Monel alloys
Monel alloys are the mildly ignitable materials therefore they are commonly utilized in the structures. Monel alloy 400 and K-500 do not ignite in the particle impact experiments and prevent inflammation in the tests when the oxygen pressure is very high even about 69 MPa. The Monel grades catch fire in the frictional heating analyses at the larger loads as compare to stainless steels, however the fire doesn’t move forward.
Ignitions are noticed in the test units developed from Monel and precautions must be followed to limit the ignition sources while building Monel equipments. Although few instructions are needed when ignition resistant materials are available than when highly ignitable materials are available and configurational testing is rarely important. Monel grades are used at pressures over 69 MPa without issues.
Monel and Monel alloys are ignitable in highly divisional structures for example mesh and sintered powder.
Monel grades are hardly chosen for flight units as these structures are made from heavy materials. Although Monel alloys are usually received in the essential levels of hardness and strengths, these are recommended for use in the ground base and manually controlled equipments when the price of safe service with other materials is considerably large. In the aerospace units, when weight is a key factor, Monel alloys are used to provide additional security from ignition as well as fire sensitive areas without adding the weight. Practically, the strength to weight ratio offered by Monel is higher than aluminium.
The Hastelloy mesh grades for example C276 are also ignition resistant even superior than Inconel 718 and steel grades.
Stainless steel grades
Stainless steels are much more ignition and inflammation resistant as compare to titanium and aluminium based alloys. These materials are widely used in the high pressure oxygen units that demand good resistance to ignition as well as flame. While using the stainless steels, some issues occur such as with steel tanks and lines. However stainless steel particulate can fire materials, these are less riskier than aluminium particulate. Stainless steel grades offer high heats of combustion and are ignited more conveniently through frictional heating.
Copper and copper alloys
Copper is also used in oxygen units at the wide range of pressure limits. It is specifically significant for preventing ignition by particle impact and hence can be utilized as impingement plates.
Copper also prevents ignition and combustion, even also has a small ductility oxide that is not persistent. It may result into contamination in the oxygen equipments.