A fire pump is treated not as an ordinary water pump but as part of a life safety system. The motor must be replaced in line with the fire standard on which the installation is based, the requirements of the insurer and the competent authority, and the conditions of the pump set manufacturer. Since some projects require an approved pump–motor unit, it must be clarified before the replacement whether such a requirement applies.

DRG-250M-6 37 kW 1000 rpm cast iron frame DRG three-phase motor – fire pump motor replacement

Documentation and approval

  • Do the project report and the pump set documentation contain any specific approval or documentation requirement for the motor?
  • Does the insurance policy or the inspection body require a test and report after the replacement?
  • Who will carry out the replacement and who will sign the test report?

No fire pump approval is claimed for DRG motors; if such a requirement exists, the project's specification must be followed. Even where there is no such requirement, the replacement should be carried out by a qualified fire protection contractor.

Technical requirements

Power that covers the whole curve

A fire pump is also run above its rated flow during tests and in a fire. Since the power of a centrifugal pump rises as flow increases, the motor must be chosen not just for the rated point but for the highest power point on the curve.

Same speed and direction of rotation

Because the pump's head varies with the square of speed, the new motor must have the same number of poles (the same speed class) as the old one. The direction of rotation is verified at the first start.

Supply and control

The fire pump controller, a dedicated supply line and the protection arrangement are subject to different rules from those for ordinary pumps. Implementation depends on the motor nameplate, the manufacturer's documentation and the assessment of qualified electrical personnel.

After the replacement

Once the motor is fitted, the pump set should be tested at closed valve, rated flow and overload flow points, and the pressure and current values recorded. The jockey pump motor is assessed separately from the main pump, and frequent starting of the jockey pump often points to a leak in the installation.

The distinction between the main pump and the jockey pump is explained in detail on the fire pump motor page. If the project requirements allow, you can browse cast iron frame models by power and speed in the shop.