Pumping Abrasives

Masterflex pumps are well suited for pumping abrasive slurries for several reasons: The peristaltic pumping action is gentle on the fluid, this reduces wear on the tubing. The only part of the pump the fluid is in contact with is a smooth piece of tubing, there are no fittings or valves for particles to clog. Abrasive materials will shorten the life of any pump, but the tubing is quickly and inexpensively replaced. Follow these suggestions to get the maximum performance from your peristaltic pump:

1. Choose abrasion resistant tubing. Norprene^®, PharMed^® and Viton^® all have good abrasion resistance. Tygon^® is fair with abrasives, and silicone and C-FLEX^® are only moderately resistant to wear from abrasive materials.

2. Use an adjustable occlusion pump head. The standard occlusion for all Masterflex fixed occlusion pump heads is shown in Figure A. Abrasive materials, especially hard particles are pressed into the tubing wall and cause a great deal of wear. Using a variable occlusion pump head allows you to reduce the amount that the tubing is being squeezed (see Figure B). The result is less wear on the tubing. By increasing the occlusion to prime the tubing and then reducing the occlusion to pump, you will get the maximum performance from your pump with the least amount of wear on the tubing.

3. Select a larger size tubing. This will reduce the rate that particles are coming into contact with the tubing wall. Soft particles should have an ID less than 25% of the ID of the tubing. Hard particles should be even smaller in relation to the ID of the tubing, they should be less than 5%. Keeping these ratios will reduce the rate that the tubing is being worn from the inside. Figure C illustrates this point.

4. Slow down the speed of the drive. This will cause a more gentle pumping action and increase the life of your tubing. Since many slurries are also viscous, slowing down the drive speed will also increase the efficiency of the pump. For more information on pumping viscous fluids, see Pumping Viscous Fluids.