These systems provide compressed air within the range of 1,000 to 6,000 psig pressure. Hazards that increase with higher pressures and capacities can be minimized by using separate compressors for each required pressure. Systems operating at 3,000 psig may require small amounts of air at lower pressures, which is supplied through pressure-reducing stations. Always use caution with HP systems! When HP air enters suddenly into pockets or dead ends, the air temperature in the confined space increases dramatically. If there is any combustible material in the space and the air temperature increases to the ignition point of the material, an explosion may occur. Explosions of this type may set up shock waves that travel through the compressed air system. This travel may cause explosions at remote points. Even a small amount of oil residue or a small cotton thread may be sufficient to cause ignition.

Some common pressure requirements for HP systems may be as follows:

Figures 6-5 and 6-6 show a maintenance index page (MIP) for one design and make of an HP air compressor system. This will give you an idea of the differences in planned maintenance requirements between the LP air (see figs. 6-2, 6-3, and 6-4 for comparison) and HP air systems. It is very important that the PMS you are using are the correct ones.

You should inspect air flasks, receivers, separators, and piping for damage or external corrosion once every 6 months. Enter the inspection date and results in the Maintenance and Material Management (3-M) Systems by submitting a work request for any discrepancies found. You must document completion of all inspection results through PMS.