When dealing with steam or electrically driven cargo pumps the following procedures are to be followed:
- The Duty Engineer must be given adequate notice of starting or stopping cargo pumps.
- The pumproom is to be checked as soon as possible after any pump unit is started.
- The pump casing is to be vented of air or gas and primed full of liquid before starting the pump.
- Starting of steam driven centrifugal pumps is to be done in accordance with the manufacturer instructions, and to be closely monitored by the Duty Engineer.
- Centrifugal pumps are not be run above minimum speed until the Duty Engineer is satisfied with the operating condition of the drink unit.
- Steam driven centrifugal pumps must be started against a closed discharge valve. Once the pump is turning the valve should be opened gradually as the pump is brought slowly up to the desired operating speed.
- Electrically driven centrifugal pumps which run at constant speed, are to be started against a closed discharge valve. Once the pump is running the discharge valve is to be opened until the desired discharge pressure is achieved.
- The stopping of steam driven centrifugal pumps must be carried out by the Duty Engineer, however, routine stopping may be carried out using remote controls providing prior notice has been given to the Duty Engineer.
- The stopping of electrically driven pumps may be carried out from the Cargo Control Room.
Before stopping the pump the load on the pump is to be reduced by closing in on the discharge valve. The Duty Engineer must always be advised of when such a pump is being stopped to allow him to monitor the generating plant as the electrical load changes.
You may also know about self priming :
In a self-priming system a discharge control valve performs two duties:-