Low NPSHr:
Pump length under-ground can increase an extra NPSHa value, so as to avoid damage by cavitation at impellor suction part.
Low suction pressure by special design, and pump length depends on NPSHa situation.
Impellor:
Single suction radial type, with first impellor normally suction type, inducer is avaliable asper request.
First impellor is designed between two shaft bushing according to API610 for fine supporting of rotor parts and stable performance.
First impellor double suction asper requirement.
Bearings:
Rolling bearings are thin oil lubrication with good effect.
Sub-merged sliding bearing is multi-point support with API span.
Small bearing load by good axial thrust balanced through balancing drum.
Advanced rotating and independent lubrication system realized automatic oil circulation.
The use of liquid lubricated middle supporting bearings depends on pump length.
Mechanical seal:
Single or double seal with necessary auxiliary piping systems according to API682.
API610 Centrifugal Pumps
| Overhung (OH) | Flexibly coupled | Horizontal | Foot-mounted | OH1 |
| Horizontal | Centerline-supported | OH2 | ||
| Vertical | In-line with bearing bracket | OH3 | ||
| Rigidly coupled | Vertical | In-line | OH4 | |
| Between bearings (BB) | 1 & 2 stages | Axially split | Foot-mounted | BB1-A |
| Near-centerline mounted | BB1-B | |||
| Radially split | Centerline-supported | BB2 | ||
| Multistage | Axially split | Near-centerline supported | BB3 | |
| Radially split | Single casing | BB4 | ||
| Double casing | BB5 | |||
| Vertically suspended (VS) | Single casing | Discharge through column | -- | VS1 |
| Separate discharge pipe | Line shaft | VS4 | ||
| Cantilever shaft | VS5 | |||
| Double casing | Radially split | -- | VS6 |
**Some of above types of pumps does not meet all the requirements of API610 standard.
**API610 standard suggests that, further or differing requirements can be needed for individual applications. The vendor is necessary to identify any variations from API610 standard and provide details for alternative equipment or engineering solutions.
