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How Does Peristaltic Pump Work?

- Mar 12, 2018 -

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Working Principle

 

Peristaltic pump works by rollers alternately pressing a flexible tubing to pump in and pump out liquid, similar like two fingers pressing a soft tube filled with liquid to form into negative pressure so as to make the liquid moving forward.

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During working, tube between 2 rollers seems like a pillow whose volume is decided by inner diameter of tubing and properties of rollers, flow rate is counted by product of speed, “pillow” dimension and “pillow” numbers when roller turns around 1 circle. Dimension of “pillow” is usually constant (except for high viscosity liquid).

                                                         

Take two pumps with same roller dimension as example, the one with bigger “pillow” volume will pump more liquid but bigger liquid pulse, which is similar to membrane valve. While, smaller “pillow” volume will pump less liquid but smaller liquid pulse to ensure more stable flowing, which is similar to gear pump.

 

Advantage

 

1.     Pollution free

Fluid only touch tubing with no contact with pump itself

2.     High precision

Repeatability accuracy, high stability

3.     Low blade load

Suitable for transfer sensitive shearing and strong corrosive liquid

4.     Good sealing

Good self-priming ability, idling acceptable, backflow against

5.     Easy maintenance

With no valve and sealing parts

6.     Same flow rate at CW/CCW

Peristaltic pump can work normally without liquid and without any damage on any parts; 98% vacuum; without valve, mechanical sealing and stuff filling sealing device to ensure leakage free and maintenance; easy to transfer compound liquid with solid diameter about 40% of tube inner diameter; suitable for corrosive and oxygen sensitive, food etc.; only flexible tube needs to be replaced and easy operation, target liquid only touch tubing. 

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Limitations

 

1.     Pressure

Soft tube can only support low pressure max about 0.2Mpa

2.     Peristaltic pump will lead to a pulse flow when working, solutions as below:

a.     Increase roller numbers but flow rate will be lower

b.     Use pulse controller which is an easy location container whose working principle is that air can be pressed easier than liquid, when pulse flow into the container, air upon liquid will be pressed and lowered down to absorb the pulse, so liquid can get out more stable from the pulse controller.

3.     Flow rate reduces as time goes by because tubing will be worn out.

Output pressure of the pump can’t be over 0.3Mpa, usually between 0.1-0.2Mpa.

 

Application

 

Peristaltic pump can be widely used in chemistry, mining, metallurgy, paper processing, paint, food, ceramic, oil, water treatment, pharmacy, medical device etc.

 

For example: Pharmacy

Peristaltic pump play the role on medicine covering processing and distribution in pharmacy. Medicine processing needs spray drying granulator, also named drying granulator and fluidic granulator, which is used to spray special sugar coatings on the surface of target instant particles then formed into particles. The granulator will cause heat during working to evaporate the water, but water evaporation and particles forming are dynamically changing so it needs to pump in accurate water or liquid to ensure relative humidity then form perfect pellet medicine. 

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 www.runzefluid.com

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