Peristaltic pump
A tube pump , also peristaltic pump , roller, roller pump or peristaltic pump called, is a positive displacement pump in which the medium to be delivered by external mechanical deformation of a tube is forced through them.
Layout and function
The hose is supported on the outside of the pump head housing and is clamped from the inside by rollers or sliding blocks that turn on a rotor (radial active system) or are moved via a camshaft (linear or horizontal active system). With both types of construction, the movement causes the pinch point to move along the hose and thereby propel the medium forward. In standard hose pumps, the suction vacuum is generated by the elasticity of the hose material. Pumps with so-called "vacuum support" help to straighten the hose by creating a vacuum in the pump housing around the hose.
A distinction is made between devices with a maximum working pressure of approx. 2 bar and 16 bar. Up to 2 bar these are mainly so-called dry runners, with no lubricant in the pump head. The pump head is filled with a lubricant up to 16 bar , which also has a cooling function.
The pump head of an ideal peristaltic pump should have an infinitely large diameter, and the diameter of the pressure rollers should also be as large as possible. Such an ideal hose pump would have an unlimited hose life and the flow would be constant and pulsation- free.
However, such hose pumps cannot actually be manufactured. The design of a peristaltic pump can approach these ideal parameters. An example of a solution is shown here. The pump head and the pressure rollers have a very large diameter. The asymmetrical hose track also increases the efficient head diameter. Correct selection of the design parameters can significantly increase the service life of the hose and keep the flow constant for longer, with significantly reduced pulsation.
advantages
- Conveying hoses that can be adapted to many conveying media are available
- suitable for continuous operation with the correct choice of size, speed, pressure range and hose material
- Completely closed system with smooth surfaces, easy to sterilize
- no contamination of the conveyed material by lubricants from the pump
- no valves
- gentle conveyance of sensitive goods such as B. Blood cells that would be destroyed by rapidly rotating propeller blades
- Pumping of media with larger solid particles is also possible
- precise metering of very small delivery rates possible
- safe to run dry
- minimal maintenance expense
- Ability to convey higher viscous (thick) media
- In comparison with other positive displacement pumps, even, relatively shock-free delivery
- self-locking
disadvantage
- Relatively short hose life due to heavy flexing and unsuitable design (see above), especially with a simple construction without a molded hose guide (hose bed)
- Risk of hose damage if the pump and the pumped medium are not designed correctly ( chemical resistance and solid contamination)
- Abrasion from the hose can contaminate the conveyed material
- With increasing hose wear , the delivery rate and pressure decrease
- the delivery rate is not constant but swelling
The factors are primarily caused or reinforced by incorrect interpretation.
application
- Dosing pumps for liquid colors in plastics processing
- most infusion pumps
- Blood pumps in dialysis machines and heart-lung machines
- Pumping of dangerous goods (e.g. radioactively contaminated liquids)
- Sampling for Brix measurement (beverage production)
- Concrete pumps (construction)
- Pumping condensate in air conditioning systems
- Dosing pumps for detergents and rinse aids in commercial dishwashers
