The combined result will be an economical fluids handling system to acquire, operate, and maintain. Multichannel pumping is generally carried out using peristaltic pumps. These are available with a wide range of interchangeable multichannel pump heads, drives, and tubing. Multichannel peristaltic pumps are used successfully in many industries including printing, pharmaceutical, chemical processing, agriculture, and water treatment.
Applications, besides general fluid transfer duties, include metering and dispensing. The most important advantage of the peristaltic pump lies with the use of tubing as the pump chamber. The fluid being pumped remains inside the tubing at all times, so it cannot escape and cause contamination. And it will not become contaminated by the pumping operation, assuming of course that the tubing material has been properly specified.
Manifolds
When a manifold is constructed to provide a common inlet for several tubes, it reduces the number of plumbing lines to a reservoir. Remember to take care and use larger tubes when manifolding on either suction or discharge side, so that you minimize pump cavitation.
Bed Designs
Arcuate tube beds pivot with a hinge on one side and the adjustment mechanism for occlusion on the other. The tubing bed swings in an «arc» radius. The point of occlusion is at a right angle to the tubing.
Rollers
The rollers not only rotate, but literally roll across the tubing. This limits the distortion of the tubing, which is normally caused by dragging a roller over it.
Water-like fluids move easily through many different sizes of tubing.
Pump Heads
Frequent tubing changes greatly affect pump set-up and maintenance times. Some stackable pump head styles require the pump head to be dismantled in order to replace the tubing.
Stackable pump heads can be added or removed as needed for different applications. Stackable pump heads are therefore popular for applications that require flexibility to frequently reconfigure the pump design. Stackable heads are preferred for larger tubing sizes, and when the application involves high suction lift and/or discharge pressure. They require special multichannel mounting hardware for stacking, but provide better control of occlusion and tubing retention.
These staggered rollers limit the torque loading on the drive circuit when several pump heads are mounted together.
Cartridge pump heads are available separately, or integral to the design of the pump. Cartridge pumps have long rollers that provide synchronous fluid delivery between the cartridges. These pumps are recommended for low volume fluid transfer applications.
Occlusion
You simply load the tubing into the pump head, then begin pumping. After loading the tubing, start the pump. Increase the occlusion on the tubing until there is flow, then adjust a few degrees more. Installing high tolerance flow-rated tubing in this type of pump allows delivery of fluids with a high degree of flow accuracy.
Motor Torque
High flow rates require larger tubing sizes. Larger tubes have a larger tubing-to-roller interface and more material to compress. Harder durometer tubing materials require more energy to squeeze the tubing. Softer durometer tubing materials like silicone, with a durometer less than 55 shore A, need comparatively small motors, and provide substantial savings in terms of pump purchase price and operating costs.
Drive Selection
Select a drive with sufficient torque and speed to meet the flow and pump head requirements. Fixed-flow drives are fine for basic transfer applications. They are compact, with low energy requirements. Flow rate display is possible, although this will be for only one channel unless a number of flowmeters have been built into the system.
Applications
Fixed occlusion pumps are popular for their consistent tube loading and pumping capability. Used with precision extruded tubing, these pumps can deliver fluids with an accuracy of 3 to 5% between channels. The synchronous rollers provide coordinated fluid delivery between each channel in the pump head. With adjustable occlusion, these pumps can deliver flow accuracies of 1% between channels.