Can I Pump Through an Idle Pump?
The short answer is “yes, you can,” though in general this is not recommended. But in some cases, pumping through an idle pump may make more sense than taking the pump out of service.
Pumping slurry through an idle pump wastes energy because the rotating impeller reduces head; you have to use more energy to keep pressure up. Pumping through an idle pump also produces turbulence caused by undesirable flow patterns that can wear out the wet-end parts of the pump, in some cases faster than in a normally operating pump.
However, there are limited situations in which pumping through an idle pump is a practical choice. In particular, for long-distance pipelines that have multiple pumps operating at a constant speed (that is, they don’t use variable-speed controllers) and need to reduce line capacity for a few weeks or months, pumping through an idle pump may be more cost efficient than removing the pump from service altogether.
If you opt to pump through an idle pump temporarily, keep in mind these caveats:
- Don’t put a locking device on the impeller — let it rotate freely. Locking the impeller increases the chances that it will become partially unscrewed from the shaft, causing the impeller to push against the shaft liner and allowing slurry to enter the shaft.
- Even if the pump will be idle for a while, start it at least once to ensure that the impeller is screwed securely to the shaft.
If you take these preventive measures, you should be able to pump through an idle pump on your line and minimize wear and tear.