With peristaltic pumps and diaphragm pumps sharing many common applications, the challenge then becomes deciding on which type of pump is best suited for a specific application. Warren Dale of Sepro Mixing & Pumping walks through the pumping mechanisms of both types of pumps, the advantages and disadvantages of these mechanisms, and how this affects long term costs.
How Diaphragm Pumps and Peristaltic Pumps Work
Diaphragm pumps can be either single diaphragm or double diaphragm. As Warren describes in the video, a simple explanation of the mechanism of diaphragm pumps is to imagine water cupped in two hands; when the hands squeeze together, the water will fly out. Force is required to operate the diaphragms similarly, and in most cases, air is used to move the diaphragms backwards and forwards. The need for air means that diaphragm pumps require a compressor in addition to the pump itself.
The membrane mechanism of pumping requires a series of valves, often a ball in a seat, because as the diaphragm opens, the valve opens to draw product in. When the diaphragm closes, the valve closes and an opposite valve opens to pump out the product.
A peristaltic pump moves product through a hose being compressed by a series of rollers, typically two or three. As the rollers move, they compress the hose and push the product out one end of the pump. On the other end of the hose, product is pulled in as the hose once more expands. This method of pumping requires only the force needed to move the rollers and has no valves within the pump.
Advantages and Disadvantages
Peristaltic pumps excel in difficult or corrosive applications: the peristaltic pump hose life is long and there are notably long periods between required maintenance. With these challenging applications, the diaphragms within double diaphragm pumps require maintenance five or six times in the same period as a single peristaltic hose.
For sticky products or products with high solids content, solids can build up within the seat of the valve causing them to close incompletely, fail to open correctly, or in some cases, prevent the pump from pumping all. By not having any valves, peristaltic pumps avoid issues of build-up.
Double diaphragm pumps can tolerate higher upper-temperature limits than peristaltic pumps. While peristaltic pumps use natural rubber hoses, diaphragm pumps can use Teflon membranes to tolerate higher temperatures.
Diaphragm pumps require a compressor and often a backup compressor in case the primary unit fails. As a result of requiring a compressor, diaphragm pumps are typically accompanied by much higher levels of noise compared to a peristaltic pump.
Diaphragms pumps are relatively inexpensive as a capital purchase, however, the need for a compressor, frequent maintenance, and higher consumption of replacement parts results in higher operating costs over the lifetime of the pump relative to peristaltic pumps.
Not sure what pump is best suited for your application? Contact the industrial mixing experts at Sepro Mixing and Pumping.