What are the different types of pump?
Short answer
| Aspect | Positive Displacement | Centrifugal |
|---|---|---|
| Flow characteristic | Constant flow at varying pressure | Flow falls as pressure rises |
| Priming | Self-priming | Needs priming |
| Pressure protection | Relief valve required | Discharge valve |
| Viscous fluids | Suitable | Not suitable |
- Main classes: positive displacement and centrifugal
- Positive displacement subtypes: reciprocating, lobe, gear, rotating piston, screw, vane
- Centrifugal subtypes: volute casing, diffuser
- Variable delivery: swash plate, Hele-Shaw
- Flow characteristic: positive displacement constant flow at varying pressure; centrifugal flow falls as pressure rises
- Priming: positive displacement self-priming; centrifugal needs priming
- Protection: positive displacement requires relief valve; centrifugal uses discharge valve
- As Second Engineer: select, operate and maintain pumps to match system flow, pressure and fluid needs
Full answer
The full answer explains each point step by step, with the regulations and figures behind it and the discussion from other candidates. It is in the MEO Class II section of the Marine One forum, open to members enrolled for the MEO Class II exam.