FAQ: What is a peristaltic pump, and how is it used in fluid application?

What is a peristaltic pump, and how is it used in fluid application?

At Designetics, we understand that manufacturers are looking for ways to increase productivity, worker safety, and quality. This is why we developed a range of automated and semi-automated fluid application systems that deliver precise, consistent fluid to the applicator, according to the customer’s volume specification. At the heart of these systems is a type of positive displacement pump known as a peristaltic pump. But what, exactly, is a peristaltic pump, and why did we choose to build our fluid dispensing systems around this technology?

 

A primer on peristaltic pumps

Pumps can generally be divided into two categories: rotodynamic (pumps that use an impeller to move fluid, including centrifugal pumps) and positive displacement. Pumps in the positive displacement category – which includes peristaltic pumps – operate by trapping a fixed volume of fluid in a cavity and then forcing that fluid into a discharge pipe or, in the case of fluid application, into a tube that feeds the applicator.

One of the key features of positive displacement pumps is their ability to produce constant flow at a given speed, even if the discharge pressure changes. Positive displacement pumps are also considered low-shear pumps – that is, they move fluids gently, without causing shear, or relative motion between layers of the fluid, which is especially important when automated solutions are used to dispense fluids of varying viscosity.

Designetics e3minimax fluid application pump
Designetics, Inc. e3 fluid dispense systems use positive displacement peristaltic pumps to provide smooth, accurate fluid application.

 

Of all the positive displacement pump types – gear, diaphragm, piston, and peristaltic, to name a few – why did we choose to use peristaltic pump technology in our automated and semi-automated fluid applicator systems? Simple – the peristaltic pump design puts only one component in contact with the fluid – the pumping tube. Here’s how a peristaltic pump works…

The pump housing contains a semi-circular or u-shaped tube, or hose, through which the fluid flows. Rollers or “shoes” rotate about a fixed point in the center of the pump, and alternatively squeeze and release the tube. As one roller crosses over the pump inlet and the hose returns to its original shape from being compressed by the roller, a vacuum is created, which pulls fluid into the tube. When the next roller passes over the inlet, it stops the intake of fluid, creating a fixed section of tubing filled with fluid. When the first roller reaches the pump discharge, the fluid flows out, being “pushed” from behind by the following roller. The complete occlusion, or compression, of the tube prevents fluid backflow and ensures high-accuracy dispensing.

 

Why peristaltic pumps are ideal for fluid dispensing

The peristaltic pump design puts only the tubing in contact with the fluid. The standard tubing used by Designetics is compatible with a wide range of chemicals, and if your application involves a chemical that’s new to us, we test compatibility and performance in-house. If the application requires an alternative tubing material to ensure chemical compatibility, our team has experience with a wide range of materials and can select the best tubing for your application.

Using a peristaltic pump also allowed us to develop fluid dispensing systems that are air-tight, from the bottle to the pump, to the end-of-arm tooling, and down to the applicator. A single piece of tubing serves the entire system, so there are no connections that could allow air to enter the system or introduce drips or leaks. This means your fluids are protected from air exposure, and your employees and the environment are protected from detrimental effects due to chemical exposure. And because the fluid never comes into contact with mechanical parts, there is no downtime for maintenance such as cleaning tanks, propellers, gears, or diaphragms. This design also makes it easy to flush the tubing for product changeovers, or to switch out the tubing if needed.

In a peristaltic pump, the fluid flow rate is determined by the speed of the rollers, or shoes, with a wide range of speeds – and therefore, flow rates – possible for a given pump size and tube diameter. Our original automated fluid applicator systems, the e3mini and e3multi, offer three motor choices to accommodate different speed ranges: 0 to 60 rpm, 5 to 115 rpm, and 15 to 250 rpm.

Our newest automated dispensing system – the e3minimax – is driven by a servo motor that can cover the entire speed range, from 0 to 250 rpm. With the servo-driven e3minimax, you can use the same pump (and motor) for both high-speed pumping requirements and low-speed applications for very “thin” fluids.

At Designetics, we’ve developed fluid application systems based on technologies that provide the most accurate, precise, and reliable dispensing possible for virtually any fluid on any substrate. Coupled with our fluid applicators, these automated and semi-automated systems are designed to meet your specific dispensing requirements, increase your productivity, and improve worker safety and environmental protection. To learn more about our fluid applicators and dispensing systems, please reach out to us. We’d love to hear about your application and help you find the best solution.

 

 

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