04-04-2012, 12:20 PM
PERISTALTIC PUMP
[attachment=19431]
INTRODUCTION
Peristaltic pump is a positive displacement pump, used for a variety of fluids.
Fluids include a wide range of viscous materials that cannot be pumped by common pumps.
Fluids flow through a flexible tube fitted inside a circular casing.
The casing has a central rotor on which a number of ‘rollers’ or ‘shoes’ are attached.
The rollers push the fluids through the tube by physically compressing the tube.
The rollers does not come in direct contact with the fluid, and so it is used where fluids should be clean and cross contamination should not occur.
DESCRIPTION OF THE PUMP
Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a hollow curved casing. Casing is mainly steel.
The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system
The casing also contains a central rotor that is mounted on a central drive shaft that is supported on its own bearings
Two or more regularly pressing shoes or rollers are attached to the rotor
There are no check valves, seals, seats and glands. The only moving part in the pump is the rotor with the shoes or rollers.
WORKING OF THE PUMP
The fluid enters via tubing and is contained within a flexible hose or tube fitted inside the pump casing.
A rotating shoe or roller passes along the length of the hose or tube creating a total seal between the suction and discharge sides of the pump.
The pump’s rotor turns so the sealing pressure moves along the tube or hose forcing product to move away from the pump and into the discharge line.
Where the pressure has been released the hose or tube recovers creating a vacuum.
This draws the product into the suction side of the pump, the priming mechanism.
Combining these suction and discharge actions results in a self priming positive displacement pump
TUBE SELECTION FACTORS
Peristaltic pump is increasing in popularity because of its contamination free fluid transfer . Each application requires its own type of tube material. So when designing, tube material selection, is an important factor. The factors are
ADVANTAGES
No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube, it is easy to sterilize and clean the inside surfaces of the pump.
Low maintenance needed since no valves, seals or glands.
They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
Since there are no moving parts they are inexpensive to manufacture.
They are reversible and can pumps in both directions.
They are dry running and self-priming.
DISADVANTAGES
Tube life is limited.
Pulsating flow but pulsations can be reduced by using pulsation dampeners which increase cost.
Selection of tubes for the required purposes can be sometimes difficult.
Pumps require frequent calibration to correlate flow rate and pump speed.
Cannot pump above 10 meters.
CONCLUSION
Peristaltic pumps have become a critical and reliable part of processes ranging from chemical transfer to pharmaceutical processing to wastewater treatment. Their versatility and ease of use has helped them meet a multitude of fluid-handling challenges.
[attachment=19431]
INTRODUCTION
Peristaltic pump is a positive displacement pump, used for a variety of fluids.
Fluids include a wide range of viscous materials that cannot be pumped by common pumps.
Fluids flow through a flexible tube fitted inside a circular casing.
The casing has a central rotor on which a number of ‘rollers’ or ‘shoes’ are attached.
The rollers push the fluids through the tube by physically compressing the tube.
The rollers does not come in direct contact with the fluid, and so it is used where fluids should be clean and cross contamination should not occur.
DESCRIPTION OF THE PUMP
Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a hollow curved casing. Casing is mainly steel.
The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system
The casing also contains a central rotor that is mounted on a central drive shaft that is supported on its own bearings
Two or more regularly pressing shoes or rollers are attached to the rotor
There are no check valves, seals, seats and glands. The only moving part in the pump is the rotor with the shoes or rollers.
WORKING OF THE PUMP
The fluid enters via tubing and is contained within a flexible hose or tube fitted inside the pump casing.
A rotating shoe or roller passes along the length of the hose or tube creating a total seal between the suction and discharge sides of the pump.
The pump’s rotor turns so the sealing pressure moves along the tube or hose forcing product to move away from the pump and into the discharge line.
Where the pressure has been released the hose or tube recovers creating a vacuum.
This draws the product into the suction side of the pump, the priming mechanism.
Combining these suction and discharge actions results in a self priming positive displacement pump
TUBE SELECTION FACTORS
Peristaltic pump is increasing in popularity because of its contamination free fluid transfer . Each application requires its own type of tube material. So when designing, tube material selection, is an important factor. The factors are
ADVANTAGES
No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube, it is easy to sterilize and clean the inside surfaces of the pump.
Low maintenance needed since no valves, seals or glands.
They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
Since there are no moving parts they are inexpensive to manufacture.
They are reversible and can pumps in both directions.
They are dry running and self-priming.
DISADVANTAGES
Tube life is limited.
Pulsating flow but pulsations can be reduced by using pulsation dampeners which increase cost.
Selection of tubes for the required purposes can be sometimes difficult.
Pumps require frequent calibration to correlate flow rate and pump speed.
Cannot pump above 10 meters.
CONCLUSION
Peristaltic pumps have become a critical and reliable part of processes ranging from chemical transfer to pharmaceutical processing to wastewater treatment. Their versatility and ease of use has helped them meet a multitude of fluid-handling challenges.