SPEED LIMITS FOR SLURRY PUMPS S074
Impeller tip speed is the guide we use for slurry pumps to prevent excessive wear rates.
- With dirty water, limit the impeller tip speed to 130 feet/ second (40 m/s)
- Up to 25% solids and solids size to 200 microns, limit the tip speed to 115 feet per second (35 m/s).
- For slurries with higher concentrations than 25%, and solids larger than 200 microns, limit tip speed to 100 feet/ second (30 m/s).
- Rubber type impellers are usually limited to 85 feet/ second (26 m/s)
Here is some more information you can use:
- You must pump the slurry at a velocity of 4 to 7 ft/sec. (1,2 to 2,3 meters / sec. to prevent a bed of solids in the pipe.
- The frictional loss in a pipe increases approximately as the square of the flow velocity Try to keep the velocity as low as possible
- Pipe abrasion becomes a problem when you pump greater than 10 Ft./sec. (>3 Meters/ sec)
- The slurry can cause several problems with the pump and any mechanical seal that might be installed:
- Internal pump passages can clog, restricting product flow
- The impeller can be put out of balance, causing excessive shaft movement and vibration problems that will affect both the seal and bearings.
- If you are using semi-open or open impellers, you will need frequent impeller adjustments to prevent internal recirculation problems. Without a cartridge seal design, sensible impeller adjustment is almost impossible
- Closed impeller, wear ring excessive wear can become a problem causing internal recirculation problems
- If you are using welded metal bellows seals you will experience wear of the bellows plates and a possible rupture at higher pressures.
See: Slurry sealing SA010