The need for a water pressure booster pump can also arise after the installation of a backflow prevention device (BFP), which is currently mandated in many municipalities[where?]

These devices can cause a loss of 12 PSI, and can cause flushometers on upper floors not to work properly.

After pipes have been in service for an extended period, scale can build up on the inside surfaces which will cause a pressure drop when the water flows.

Most applications run off AC mains current and use an inverter to control motor speed.

A small auxiliary electrically-powered booster pump (called a "jockey pump") is often included in the system to maintain the sprinkler pipes at sufficient pressure, without requiring startup of the large diesel engine.

In recent years, a larger electrical pump with substantial battery backup may be substituted for the diesel engine, reducing but not eliminating the need for maintenance.

Examples include: Gas booster pumps are usually piston or plunger type compressors.

[1] Gas boosters may be driven by an electric motor, hydraulics, low or high pressure air, or manually by a lever system.

It is necessary to ensure that drive air, which may not be sufficiently clean for safe contact with high pressure oxygen, cannot leak past the seals into the booster cylinder, or high pressure oxygen can not leak ito the drive cylinder.

Any gas leaks from either cylinder past the rod seals escapes harmlessly into the ambient air.

[1] Electrically powered boosters may use a single or three-phase AC motor drive.

Some of these boosters allow for the connecting rod to be disconnected and a pair of long levers to be fitted for manual operation in emergencies or where electrical power is not available.

[1] Manual boosters have been made with the configuration described above, either with a single vertical lever or with a seesaw styled double ended horizontal lever, and also with two parallel vertically mounted cylinders, much like the lever-operated diver's air pumps used for the early standard diving dress but with much smaller bore to allow two operators to generate high pressures.

Rugged and unsophisticated models (KN-3 and KN-4) were manufactured for the Soviet Armed Forces and surplus examples are now used by technical divers as they are relatively inexpensive and are supplied with a comprehensive spares and tool kit.