Compressors

Hydrogen gas supply pressures are often lower than the use pressure whether supplied by tube trailers, pipeline, or a liquid hydrogen tank. Compressors are used to increase pressure of hydrogen gas.

Compressors are commonly driven by electric motors, pneumatic cylinders, or hydraulic cylinders. When electric motor drive systems are used, they must meet the electric classification requirements for equipment in a hydrogen environment.

Electrochemical hydrogen compressors represent an emerging technology that may be suitable for some future applications.

Considerations for compressor installation include:

• Combustible compressor lubricants can present a fire hazard.
• The compressor discharged pressure should be monitored by a control system and shut down the compressor when the discharge pressure reaches the target value.
• Compressor discharges should be equipped with a relief device to prevent system over pressure when the pressure control fails (see Compressed Gas Relief Devices). 
• The compressor should be shut off when the Emergency Shutdown System (ESS) is activated.
• Compressors should be monitored for wear and failure conditions that may cause hydrogen leakage either internally or externally.