Centrifugal pump for fire fighting - has priming pump automatically controlled according to both speed and discharge pressure

摘要

The fire fighting pump (1) and its priming pump (2) are driven by a common motor (4) through a gear box (3). A controller (5) operates a clutch (6) and a valve (7) to disengage the priming pump when the main pump discharge pressure (9) reaches a preset value. A tachometer (10) on the motor provides a signal which stops the controller from acting below a preset speed and prevents the priming pump being started below that speed. This prevents priming being stopped too soon. A switch (12) on the gear drive (3) provides a signal which activates a positioner (13) to increase the speed of the motor. This brings the pump into action quickly.