A peristaltic pump is one of the most frequently used pumps for transferring liquids from one point to another. Mostly it is used in medical applications and laboratory applications. In medical applications like dialysis, it proves very useful to transfer blood from one part to another part. The best thing in this pump is the liquid to be transferred does not comes in contact with the pump. It remains in the pipe which is used to carry or transfer the fluid. So any chance of contamination of liquid is completely out of scope. In laboratory applications, it is often used to fill vessels with precise volume. The task can be repeated and hence filling a number of vessels becomes easy. Its operation is very much different than the vacuum pump.
What is the Peristaltic Pump?
Definition: Peristaltic pump or also called a chemical feed pump refers to the way by which it moves the liquid from one part to another part. The word peristaltic means frequent compression and release. Here in this context, it means that frequent compression and releasing of the pipe creates a pressure difference and hence enables the pump to transfer liquids.
As shown in the figure, the blue shade indicates a hosepipe through which the liquid is transferred. The triangular shaft in middle rotates with the help of an electric motor connected to its shaft. The red arrows above indicate the motion of the triangular shaft. On the outside part, two inlets indicate the incoming and outgoing path for the liquid. It could be noted that the direction of the flow of liquid is reversible. On rotating the shaft in the opposite direction, the flow of liquid also changes.
Working Principle of Peristaltic Pump
The fundamental principle behind the working of a peristaltic pump is liquid transfers from one point to another, on creating a pressure difference. As shown in the figure, when the triangular rotor of the pump is connected to the shaft of the motor. When the motor is given supply, it rotates the triangular rotor.
The triangular rotor of the pump presses the hose pipe. On the top of the triangular rotor, there is an arrangement, such that when the rotor comes in contact with the hose pipe, it presses and releases the pipe. This action can be termed as peristaltic. On such movement, the liquid inside the hose pipe is pushed forward. Precise control on the speed of the shaft avoids air gaps in the liquid. Since the liquid is pushed forward in the hose pipe, the liquid does not come in contact with the pipe and hence this avoids contamination of the liquid.
This makes the peristaltic pump ideal for moving chemicals or liquids that do not want to get cross-contaminated. The amount of liquid or chemical to be transferred can be easily controlled either by adjusting the diameter of the hose pipe or controlling the speed of the shaft.
Types of Peristaltic Pumps
There are basically two types of peristaltic pumps
- Hose pumps type peristaltic pump
- Tube pumps type peristaltic pump
In the hose pump type, the peristaltic pump is basically used for lower flow rates. They are fully programmable and can be designed to have multiple heads. On the other hand, the tube type peristaltic pump is used for pumping liquids with high density. They cannot be used for liquids with low density. Usually, they are designed for a single head.
Peristaltic Pump Advantages and Disadvantages
The advantages of the peristaltic pump are listed below.
- The first and important advantage of the peristaltic pump is in this pump, the operating fluid is saved from cross-contamination. Since the fluid is always enclosed in the pipe, it does not comes in contact with other parts of the pump. This saves the fluid from contamination or adulteration. This advantage specifically helps the pump to be used for medical procedures.
- Due to the mechanism of the pump, it allows precise control of the volume of the liquid to be transferred. The precise control allows the fluid to be filled in other containers and easily handled.
- Digital control of the pump. A digital signal processor can be embedded with the pump which enables the pump to have precise control. Precise control in the sense periodic release of fluid, control on volume, etc. Digital control also allows controlling the flow rate of the fluid, pressure, etc to be easily controlled.
- Electric Motor – Since the shaft is connected to an electric motor, this allows control over the volume of fluid. Since the speed of the motor can be easily controlled, it also controls the volume of the liquid to be transferred.
The disadvantages of the peristaltic pump are listed below.
The peristaltic pump has a limited number of disadvantages. One of them is the size of the hose pipe. This restricts the volume of the fluid to be transferred. The other major disadvantage is the wear and tear of the hose pipe. Since the hose pipe comes under pressure constantly from the rotor shaft, it becomes very important to note the healthiness of the pipe. Any small leakage in the pipe will spoil the whole application. In the case of medical units, the failure of a hosepipe can cause severe consequences. Hence it becomes very important to see the state of the pipe. In most of the cases, the pipe is replaced after every operation.
Applications of Peristaltic Pump
There is a variety of use of the peristaltic pump. It is mostly used in the medical field and for laboratory applications. In medical applications, the blood can be transferred from one part to another. In the surgical processes like dialysis, this becomes very helpful. In laboratory applications like chemical laboratories, it is used as chemical feeders. Also, it is used to fill different vessels with chemicals.
Other medical applications include pumping IV fluids through an infusion device, other liquids for which cross contaminations have to be strictly avoided, aggressive chemicals, etc. They are also used in critical operations like bypass surgery hemodialysis etc. Apart from medical and laboratory applications, they are also used in agriculture applications to pump out huge quantities of water. Also suited to induce some agriculture chemicals on the crops. Also used to pump abrasives and viscous fluids.
1). Can a peristaltic pump air?
No, peristaltic pump cant pump air as precisely it can pump liquids. A small amount of air can be transferred, but these pumps are not suitable for that application.
2). How accurate are peristaltic pumps?
Ans. The accuracy of peristaltic pumps can be as good as + 0.5%. Many applications such as medical units require precise control of fluids. For that reason, peristaltic pumps are preferred.
3). What kind of chemical feeder is a peristaltic pump?
A peristaltic pump is a type of positive displacement pump which is used to displace fluids from one point to another.
4). What is a peristaltic flow?
Peristaltic flow is the flow of liquid through a medium such as a hose pipe due to peristaltic action. The peristaltic action implies continuous compression and release of the pressure on a particular medium.
5). How deep can a peristaltic pump?
The peristaltic pump can be deep up to 30 feet.
Hence we have seen the working principle of peristaltic pumps along with their advantages and disadvantages. A brief classification of the pumps has also been discussed. It can be also noted that the peristaltic pump operation is reversible in nature. Here arises an interesting aspect that which type of electric motor is suitable for the peristaltic pump? Keeping in view of its operation, precise control, reverse operation, etc. which motor suits best for the peristaltic pump.