29-03-2012, 04:02 PM
PERISTALTIC PUMP
1. INTRODUCTION
A lot of equipment around us uses the mechanisms of pump, from the smallest pump used in the house to the biggest scales and specification pump used in industries. A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A rotor with a number of 'rollers', 'shoes' or 'wipers' attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution') vacuum is created which draws more fluid into the tube, creating a gentle pumping action with minimal damage to the media inside the tube, particularly when compared to other methods of mechanical transfer.
2. LITERATURE SURVEY
A famous Greek Mathematician and Inventor, Archimedes (287 BC – c. 212 BC) invented the Archimedean screw pump constructed out of wood and bronze. The Archimedean screw pump is technically a progressing cavity pump. The positive displacement pump has a history that is as old as the history of pumping itself. The oldest positive displacement pump is probably the hand cranked water wheel with a number of scoops around its circumference which scoops up water from a water channel at low level and discharges it at high level via a chute into the head of another channel. Such “pumps” were used for irrigation by early farmers in the Middle East as long ago as 5,000 years ago.
3. THEORY
3.1 THE PUMP UNIVERSE
To understand the peristaltic pump we must first investigate its position within the pump universe. The pump universe can be organized in a variety of ways such as by their design, their material of construction, or the liquids they pump. We will organize the pump universe by classifying the pumps based on the method by which the pump imparts energy to the liquid being pumped. This results in two basic classes of pump: dynamic and displacement. The chart 3.1 shows the basic classification of the pumps.
3.2 BASIC CONSTRUCTION OF PERISTALTIC PUMP
The peristaltic pump is a special type of leak-free rotary displacement pump. Its construction and operating principle are completely different from the other pumps. Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a casing and is shown in figure 3.1. The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system. Fluid flows through the flexible tube or hose fitted inside a circular casing. The casing also contains a rotor that is mounted on a central drive shaft that is supported on its own bearings. The casing also serves as the lubrication chamber and is filled with lubricating oil.
WORKING OF A PERISTALTIC PUMP
Peristaltic pumps work by compressing and relaxing a hose that’s positioned between a rotating device and a circular pump housing. The actual pumping principle, called “peristalsis”, is based on alternating compression and relaxation of the hose or tube, drawing content in and propelling product away from the pump. 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. As the pump’s rotor turns this 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, which 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 peristaltic pump.
PERISTALTIC PUMP TUBING
The tube or hose is the heart of any Peristaltic Pump. A common misconception regarding peristaltic pumps is that the tubing is a major failure point, a maintenance headache for users, and must be replaced every couple of weeks or even days. Another common misconception is that achieving practical tubing life severely limits pumping speed and flow rates because the pump must operate at relatively slow speeds in order to realize adequate tubing longevity. Conventional tubing materials cannot hold up to the harsh demands of certain applications, and the lack of reliable tubing limited peristaltic pump capacities.
3.7 ADVANTAGES
• No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube.
• Low maintenance needs. Their lack of valves, seals and glands makes them comparatively inexpensive to maintain.
• They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
• Peristaltic pump is non-siphoning which means that they prevent back flow into the system.
• No cavitation
• Dry running / self-priming / seal less
• Creates high vacuum for suction lift applications
• Pumps in both directions.
• Smooth passage through the pump – no checks or obstructions.
• Accurate flow for metering applications.
• It is easy to sterilize and clean the inside surfaces of the pump.
• Since there are no moving parts in contact with the fluid, peristaltic pumps are inexpensive to manufacture.
• Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose.
• Same pump could be used to pump other fluids (just change the tube to suitable one)
• The peristaltic pump has a completely disposable fluid path and is self-priming.
• Low Vacuum Force – Peristaltic pumps typically work with soft-walled elastomeric tubing. This tubing is easily compressed but also returns to its initial shape quickly.
• Peristaltic pumps have a gentle, low shear pumping action, ideal for shear sensitive products including flocculants and broths.
• The powerful suction provided by the recovery of a re-enforced hose gives hose pumps suction lift capabilities up to 9.5m of water.
• Peristaltic hose pumps can pump slurries containing up to 80% inorganic solids or 15% organic sludge.
• The pumps have no internal backflow giving accurate dosing without slip.
• The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
• Hose design allows applications to pump aggressive and contaminated fluids.
3.8 DISADVANTAGES
• Tube life is limited.
• Selection of tubes for the required purposes can be sometimes difficult.
• The principal limitation of the peristaltic pump is that its fluid delivery is not absolutely uniform.
• The peristaltic pump can lose its feed rate as it ages, even though the peristaltic has an excellent feed rate earlier on in its operation due to less gassing, which can lead to a feed loss.
• Pumps require frequent calibration to correlate flow rate and pump speed.
• Flow can vary as much as 10-30 percent due to variations in operating pressures.
• Process optimization is difficult since flow for each process step is uncontrolled.
• Uneconomical for long distance pumping.
• Operator needs good knowledge.
• Cannot pump above 10 meters.
PERISTALTIC PUMP
1. INTRODUCTION
A lot of equipment around us uses the mechanisms of pump, from the smallest pump used in the house to the biggest scales and specification pump used in industries. A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A rotor with a number of 'rollers', 'shoes' or 'wipers' attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution') vacuum is created which draws more fluid into the tube, creating a gentle pumping action with minimal damage to the media inside the tube, particularly when compared to other methods of mechanical transfer.
2. LITERATURE SURVEY
A famous Greek Mathematician and Inventor, Archimedes (287 BC – c. 212 BC) invented the Archimedean screw pump constructed out of wood and bronze. The Archimedean screw pump is technically a progressing cavity pump. The positive displacement pump has a history that is as old as the history of pumping itself. The oldest positive displacement pump is probably the hand cranked water wheel with a number of scoops around its circumference which scoops up water from a water channel at low level and discharges it at high level via a chute into the head of another channel. Such “pumps” were used for irrigation by early farmers in the Middle East as long ago as 5,000 years ago.
3. THEORY
3.1 THE PUMP UNIVERSE
To understand the peristaltic pump we must first investigate its position within the pump universe. The pump universe can be organized in a variety of ways such as by their design, their material of construction, or the liquids they pump. We will organize the pump universe by classifying the pumps based on the method by which the pump imparts energy to the liquid being pumped. This results in two basic classes of pump: dynamic and displacement. The chart 3.1 shows the basic classification of the pumps.
3.2 BASIC CONSTRUCTION OF PERISTALTIC PUMP
The peristaltic pump is a special type of leak-free rotary displacement pump. Its construction and operating principle are completely different from the other pumps. Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a casing and is shown in figure 3.1. The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system. Fluid flows through the flexible tube or hose fitted inside a circular casing. The casing also contains a rotor that is mounted on a central drive shaft that is supported on its own bearings. The casing also serves as the lubrication chamber and is filled with lubricating oil.
WORKING OF A PERISTALTIC PUMP
Peristaltic pumps work by compressing and relaxing a hose that’s positioned between a rotating device and a circular pump housing. The actual pumping principle, called “peristalsis”, is based on alternating compression and relaxation of the hose or tube, drawing content in and propelling product away from the pump. 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. As the pump’s rotor turns this 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, which 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 peristaltic pump.
PERISTALTIC PUMP TUBING
The tube or hose is the heart of any Peristaltic Pump. A common misconception regarding peristaltic pumps is that the tubing is a major failure point, a maintenance headache for users, and must be replaced every couple of weeks or even days. Another common misconception is that achieving practical tubing life severely limits pumping speed and flow rates because the pump must operate at relatively slow speeds in order to realize adequate tubing longevity. Conventional tubing materials cannot hold up to the harsh demands of certain applications, and the lack of reliable tubing limited peristaltic pump capacities.
3.7 ADVANTAGES
• No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube.
• Low maintenance needs. Their lack of valves, seals and glands makes them comparatively inexpensive to maintain.
• They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
• Peristaltic pump is non-siphoning which means that they prevent back flow into the system.
• No cavitation
• Dry running / self-priming / seal less
• Creates high vacuum for suction lift applications
• Pumps in both directions.
• Smooth passage through the pump – no checks or obstructions.
• Accurate flow for metering applications.
• It is easy to sterilize and clean the inside surfaces of the pump.
• Since there are no moving parts in contact with the fluid, peristaltic pumps are inexpensive to manufacture.
• Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose.
• Same pump could be used to pump other fluids (just change the tube to suitable one)
• The peristaltic pump has a completely disposable fluid path and is self-priming.
• Low Vacuum Force – Peristaltic pumps typically work with soft-walled elastomeric tubing. This tubing is easily compressed but also returns to its initial shape quickly.
• Peristaltic pumps have a gentle, low shear pumping action, ideal for shear sensitive products including flocculants and broths.
• The powerful suction provided by the recovery of a re-enforced hose gives hose pumps suction lift capabilities up to 9.5m of water.
• Peristaltic hose pumps can pump slurries containing up to 80% inorganic solids or 15% organic sludge.
• The pumps have no internal backflow giving accurate dosing without slip.
• The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
• Hose design allows applications to pump aggressive and contaminated fluids.
3.8 DISADVANTAGES
• Tube life is limited.
• Selection of tubes for the required purposes can be sometimes difficult.
• The principal limitation of the peristaltic pump is that its fluid delivery is not absolutely uniform.
• The peristaltic pump can lose its feed rate as it ages, even though the peristaltic has an excellent feed rate earlier on in its operation due to less gassing, which can lead to a feed loss.
• Pumps require frequent calibration to correlate flow rate and pump speed.
• Flow can vary as much as 10-30 percent due to variations in operating pressures.
• Process optimization is difficult since flow for each process step is uncontrolled.
• Uneconomical for long distance pumping.
• Operator needs good knowledge.
• Cannot pump above 10 meters.
5. CONCLUSION
Despite all of the advantages of using peristaltic pumps for corrosive chemicals, they represent only a modest, but ever growing, percentage of the positive displacement pump market. This is primarily because peristaltic technology is relatively new in the market, whereas diaphragm and progressive cavity pumps have a lengthy history. However, to reduce life cycle costs of pumps, the functionality and benefits of peristaltic hose pumps are becoming more widely known, and new peristaltic technology is fast becoming the positive displacement pump of choice for tough chemically aggressive and abrasive applications.
PERISTALTIC PUMP
1. INTRODUCTION
A lot of equipment around us uses the mechanisms of pump, from the smallest pump used in the house to the biggest scales and specification pump used in industries. A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A rotor with a number of 'rollers', 'shoes' or 'wipers' attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution') vacuum is created which draws more fluid into the tube, creating a gentle pumping action with minimal damage to the media inside the tube, particularly when compared to other methods of mechanical transfer.
2. LITERATURE SURVEY
A famous Greek Mathematician and Inventor, Archimedes (287 BC – c. 212 BC) invented the Archimedean screw pump constructed out of wood and bronze. The Archimedean screw pump is technically a progressing cavity pump. The positive displacement pump has a history that is as old as the history of pumping itself. The oldest positive displacement pump is probably the hand cranked water wheel with a number of scoops around its circumference which scoops up water from a water channel at low level and discharges it at high level via a chute into the head of another channel. Such “pumps” were used for irrigation by early farmers in the Middle East as long ago as 5,000 years ago.
3. THEORY
3.1 THE PUMP UNIVERSE
To understand the peristaltic pump we must first investigate its position within the pump universe. The pump universe can be organized in a variety of ways such as by their design, their material of construction, or the liquids they pump. We will organize the pump universe by classifying the pumps based on the method by which the pump imparts energy to the liquid being pumped. This results in two basic classes of pump: dynamic and displacement. The chart 3.1 shows the basic classification of the pumps.
3.2 BASIC CONSTRUCTION OF PERISTALTIC PUMP
The peristaltic pump is a special type of leak-free rotary displacement pump. Its construction and operating principle are completely different from the other pumps. Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a casing and is shown in figure 3.1. The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system. Fluid flows through the flexible tube or hose fitted inside a circular casing. The casing also contains a rotor that is mounted on a central drive shaft that is supported on its own bearings. The casing also serves as the lubrication chamber and is filled with lubricating oil.
WORKING OF A PERISTALTIC PUMP
Peristaltic pumps work by compressing and relaxing a hose that’s positioned between a rotating device and a circular pump housing. The actual pumping principle, called “peristalsis”, is based on alternating compression and relaxation of the hose or tube, drawing content in and propelling product away from the pump. 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. As the pump’s rotor turns this 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, which 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 peristaltic pump.
PERISTALTIC PUMP TUBING
The tube or hose is the heart of any Peristaltic Pump. A common misconception regarding peristaltic pumps is that the tubing is a major failure point, a maintenance headache for users, and must be replaced every couple of weeks or even days. Another common misconception is that achieving practical tubing life severely limits pumping speed and flow rates because the pump must operate at relatively slow speeds in order to realize adequate tubing longevity. Conventional tubing materials cannot hold up to the harsh demands of certain applications, and the lack of reliable tubing limited peristaltic pump capacities.
3.7 ADVANTAGES
• No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube.
• Low maintenance needs. Their lack of valves, seals and glands makes them comparatively inexpensive to maintain.
• They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
• Peristaltic pump is non-siphoning which means that they prevent back flow into the system.
• No cavitation
• Dry running / self-priming / seal less
• Creates high vacuum for suction lift applications
• Pumps in both directions.
• Smooth passage through the pump – no checks or obstructions.
• Accurate flow for metering applications.
• It is easy to sterilize and clean the inside surfaces of the pump.
• Since there are no moving parts in contact with the fluid, peristaltic pumps are inexpensive to manufacture.
• Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose.
• Same pump could be used to pump other fluids (just change the tube to suitable one)
• The peristaltic pump has a completely disposable fluid path and is self-priming.
• Low Vacuum Force – Peristaltic pumps typically work with soft-walled elastomeric tubing. This tubing is easily compressed but also returns to its initial shape quickly.
• Peristaltic pumps have a gentle, low shear pumping action, ideal for shear sensitive products including flocculants and broths.
• The powerful suction provided by the recovery of a re-enforced hose gives hose pumps suction lift capabilities up to 9.5m of water.
• Peristaltic hose pumps can pump slurries containing up to 80% inorganic solids or 15% organic sludge.
• The pumps have no internal backflow giving accurate dosing without slip.
• The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
• Hose design allows applications to pump aggressive and contaminated fluids.
3.8 DISADVANTAGES
• Tube life is limited.
• Selection of tubes for the required purposes can be sometimes difficult.
• The principal limitation of the peristaltic pump is that its fluid delivery is not absolutely uniform.
• The peristaltic pump can lose its feed rate as it ages, even though the peristaltic has an excellent feed rate earlier on in its operation due to less gassing, which can lead to a feed loss.
• Pumps require frequent calibration to correlate flow rate and pump speed.
• Flow can vary as much as 10-30 percent due to variations in operating pressures.
• Process optimization is difficult since flow for each process step is uncontrolled.
• Uneconomical for long distance pumping.
• Operator needs good knowledge.
• Cannot pump above 10 meters.
5. CONCLUSION
Despite all of the advantages of using peristaltic pumps for corrosive chemicals, they represent only a modest, but ever growing, percentage of the positive displacement pump market. This is primarily because peristaltic technology is relatively new in the market, whereas diaphragm and progressive cavity pumps have a lengthy history. However, to reduce life cycle costs of pumps, the functionality and benefits of peristaltic hose pumps are becoming more widely known, and new peristaltic technology is fast becoming the positive displacement pump of choice for tough chemically aggressive and abrasive applications.
1. INTRODUCTION
A lot of equipment around us uses the mechanisms of pump, from the smallest pump used in the house to the biggest scales and specification pump used in industries. A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A rotor with a number of 'rollers', 'shoes' or 'wipers' attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution') vacuum is created which draws more fluid into the tube, creating a gentle pumping action with minimal damage to the media inside the tube, particularly when compared to other methods of mechanical transfer.
2. LITERATURE SURVEY
A famous Greek Mathematician and Inventor, Archimedes (287 BC – c. 212 BC) invented the Archimedean screw pump constructed out of wood and bronze. The Archimedean screw pump is technically a progressing cavity pump. The positive displacement pump has a history that is as old as the history of pumping itself. The oldest positive displacement pump is probably the hand cranked water wheel with a number of scoops around its circumference which scoops up water from a water channel at low level and discharges it at high level via a chute into the head of another channel. Such “pumps” were used for irrigation by early farmers in the Middle East as long ago as 5,000 years ago.
3. THEORY
3.1 THE PUMP UNIVERSE
To understand the peristaltic pump we must first investigate its position within the pump universe. The pump universe can be organized in a variety of ways such as by their design, their material of construction, or the liquids they pump. We will organize the pump universe by classifying the pumps based on the method by which the pump imparts energy to the liquid being pumped. This results in two basic classes of pump: dynamic and displacement. The chart 3.1 shows the basic classification of the pumps.
3.2 BASIC CONSTRUCTION OF PERISTALTIC PUMP
The peristaltic pump is a special type of leak-free rotary displacement pump. Its construction and operating principle are completely different from the other pumps. Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a casing and is shown in figure 3.1. The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system. Fluid flows through the flexible tube or hose fitted inside a circular casing. The casing also contains a rotor that is mounted on a central drive shaft that is supported on its own bearings. The casing also serves as the lubrication chamber and is filled with lubricating oil.
WORKING OF A PERISTALTIC PUMP
Peristaltic pumps work by compressing and relaxing a hose that’s positioned between a rotating device and a circular pump housing. The actual pumping principle, called “peristalsis”, is based on alternating compression and relaxation of the hose or tube, drawing content in and propelling product away from the pump. 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. As the pump’s rotor turns this 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, which 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 peristaltic pump.
PERISTALTIC PUMP TUBING
The tube or hose is the heart of any Peristaltic Pump. A common misconception regarding peristaltic pumps is that the tubing is a major failure point, a maintenance headache for users, and must be replaced every couple of weeks or even days. Another common misconception is that achieving practical tubing life severely limits pumping speed and flow rates because the pump must operate at relatively slow speeds in order to realize adequate tubing longevity. Conventional tubing materials cannot hold up to the harsh demands of certain applications, and the lack of reliable tubing limited peristaltic pump capacities.
3.7 ADVANTAGES
• No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube.
• Low maintenance needs. Their lack of valves, seals and glands makes them comparatively inexpensive to maintain.
• They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
• Peristaltic pump is non-siphoning which means that they prevent back flow into the system.
• No cavitation
• Dry running / self-priming / seal less
• Creates high vacuum for suction lift applications
• Pumps in both directions.
• Smooth passage through the pump – no checks or obstructions.
• Accurate flow for metering applications.
• It is easy to sterilize and clean the inside surfaces of the pump.
• Since there are no moving parts in contact with the fluid, peristaltic pumps are inexpensive to manufacture.
• Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose.
• Same pump could be used to pump other fluids (just change the tube to suitable one)
• The peristaltic pump has a completely disposable fluid path and is self-priming.
• Low Vacuum Force – Peristaltic pumps typically work with soft-walled elastomeric tubing. This tubing is easily compressed but also returns to its initial shape quickly.
• Peristaltic pumps have a gentle, low shear pumping action, ideal for shear sensitive products including flocculants and broths.
• The powerful suction provided by the recovery of a re-enforced hose gives hose pumps suction lift capabilities up to 9.5m of water.
• Peristaltic hose pumps can pump slurries containing up to 80% inorganic solids or 15% organic sludge.
• The pumps have no internal backflow giving accurate dosing without slip.
• The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
• Hose design allows applications to pump aggressive and contaminated fluids.
3.8 DISADVANTAGES
• Tube life is limited.
• Selection of tubes for the required purposes can be sometimes difficult.
• The principal limitation of the peristaltic pump is that its fluid delivery is not absolutely uniform.
• The peristaltic pump can lose its feed rate as it ages, even though the peristaltic has an excellent feed rate earlier on in its operation due to less gassing, which can lead to a feed loss.
• Pumps require frequent calibration to correlate flow rate and pump speed.
• Flow can vary as much as 10-30 percent due to variations in operating pressures.
• Process optimization is difficult since flow for each process step is uncontrolled.
• Uneconomical for long distance pumping.
• Operator needs good knowledge.
• Cannot pump above 10 meters.
PERISTALTIC PUMP
1. INTRODUCTION
A lot of equipment around us uses the mechanisms of pump, from the smallest pump used in the house to the biggest scales and specification pump used in industries. A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A rotor with a number of 'rollers', 'shoes' or 'wipers' attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution') vacuum is created which draws more fluid into the tube, creating a gentle pumping action with minimal damage to the media inside the tube, particularly when compared to other methods of mechanical transfer.
2. LITERATURE SURVEY
A famous Greek Mathematician and Inventor, Archimedes (287 BC – c. 212 BC) invented the Archimedean screw pump constructed out of wood and bronze. The Archimedean screw pump is technically a progressing cavity pump. The positive displacement pump has a history that is as old as the history of pumping itself. The oldest positive displacement pump is probably the hand cranked water wheel with a number of scoops around its circumference which scoops up water from a water channel at low level and discharges it at high level via a chute into the head of another channel. Such “pumps” were used for irrigation by early farmers in the Middle East as long ago as 5,000 years ago.
3. THEORY
3.1 THE PUMP UNIVERSE
To understand the peristaltic pump we must first investigate its position within the pump universe. The pump universe can be organized in a variety of ways such as by their design, their material of construction, or the liquids they pump. We will organize the pump universe by classifying the pumps based on the method by which the pump imparts energy to the liquid being pumped. This results in two basic classes of pump: dynamic and displacement. The chart 3.1 shows the basic classification of the pumps.
3.2 BASIC CONSTRUCTION OF PERISTALTIC PUMP
The peristaltic pump is a special type of leak-free rotary displacement pump. Its construction and operating principle are completely different from the other pumps. Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a casing and is shown in figure 3.1. The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system. Fluid flows through the flexible tube or hose fitted inside a circular casing. The casing also contains a rotor that is mounted on a central drive shaft that is supported on its own bearings. The casing also serves as the lubrication chamber and is filled with lubricating oil.
WORKING OF A PERISTALTIC PUMP
Peristaltic pumps work by compressing and relaxing a hose that’s positioned between a rotating device and a circular pump housing. The actual pumping principle, called “peristalsis”, is based on alternating compression and relaxation of the hose or tube, drawing content in and propelling product away from the pump. 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. As the pump’s rotor turns this 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, which 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 peristaltic pump.
PERISTALTIC PUMP TUBING
The tube or hose is the heart of any Peristaltic Pump. A common misconception regarding peristaltic pumps is that the tubing is a major failure point, a maintenance headache for users, and must be replaced every couple of weeks or even days. Another common misconception is that achieving practical tubing life severely limits pumping speed and flow rates because the pump must operate at relatively slow speeds in order to realize adequate tubing longevity. Conventional tubing materials cannot hold up to the harsh demands of certain applications, and the lack of reliable tubing limited peristaltic pump capacities.
3.7 ADVANTAGES
• No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube.
• Low maintenance needs. Their lack of valves, seals and glands makes them comparatively inexpensive to maintain.
• They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
• Peristaltic pump is non-siphoning which means that they prevent back flow into the system.
• No cavitation
• Dry running / self-priming / seal less
• Creates high vacuum for suction lift applications
• Pumps in both directions.
• Smooth passage through the pump – no checks or obstructions.
• Accurate flow for metering applications.
• It is easy to sterilize and clean the inside surfaces of the pump.
• Since there are no moving parts in contact with the fluid, peristaltic pumps are inexpensive to manufacture.
• Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose.
• Same pump could be used to pump other fluids (just change the tube to suitable one)
• The peristaltic pump has a completely disposable fluid path and is self-priming.
• Low Vacuum Force – Peristaltic pumps typically work with soft-walled elastomeric tubing. This tubing is easily compressed but also returns to its initial shape quickly.
• Peristaltic pumps have a gentle, low shear pumping action, ideal for shear sensitive products including flocculants and broths.
• The powerful suction provided by the recovery of a re-enforced hose gives hose pumps suction lift capabilities up to 9.5m of water.
• Peristaltic hose pumps can pump slurries containing up to 80% inorganic solids or 15% organic sludge.
• The pumps have no internal backflow giving accurate dosing without slip.
• The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
• Hose design allows applications to pump aggressive and contaminated fluids.
3.8 DISADVANTAGES
• Tube life is limited.
• Selection of tubes for the required purposes can be sometimes difficult.
• The principal limitation of the peristaltic pump is that its fluid delivery is not absolutely uniform.
• The peristaltic pump can lose its feed rate as it ages, even though the peristaltic has an excellent feed rate earlier on in its operation due to less gassing, which can lead to a feed loss.
• Pumps require frequent calibration to correlate flow rate and pump speed.
• Flow can vary as much as 10-30 percent due to variations in operating pressures.
• Process optimization is difficult since flow for each process step is uncontrolled.
• Uneconomical for long distance pumping.
• Operator needs good knowledge.
• Cannot pump above 10 meters.
5. CONCLUSION
Despite all of the advantages of using peristaltic pumps for corrosive chemicals, they represent only a modest, but ever growing, percentage of the positive displacement pump market. This is primarily because peristaltic technology is relatively new in the market, whereas diaphragm and progressive cavity pumps have a lengthy history. However, to reduce life cycle costs of pumps, the functionality and benefits of peristaltic hose pumps are becoming more widely known, and new peristaltic technology is fast becoming the positive displacement pump of choice for tough chemically aggressive and abrasive applications.
PERISTALTIC PUMP
1. INTRODUCTION
A lot of equipment around us uses the mechanisms of pump, from the smallest pump used in the house to the biggest scales and specification pump used in industries. A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made). A rotor with a number of 'rollers', 'shoes' or 'wipers' attached to the external circumference compresses the flexible tube. As the rotor turns, the part of tube under compression closes thus forcing the fluid to be pumped to move through the tube. Additionally, as the tube opens to its natural state after the passing of the cam ('restitution') vacuum is created which draws more fluid into the tube, creating a gentle pumping action with minimal damage to the media inside the tube, particularly when compared to other methods of mechanical transfer.
2. LITERATURE SURVEY
A famous Greek Mathematician and Inventor, Archimedes (287 BC – c. 212 BC) invented the Archimedean screw pump constructed out of wood and bronze. The Archimedean screw pump is technically a progressing cavity pump. The positive displacement pump has a history that is as old as the history of pumping itself. The oldest positive displacement pump is probably the hand cranked water wheel with a number of scoops around its circumference which scoops up water from a water channel at low level and discharges it at high level via a chute into the head of another channel. Such “pumps” were used for irrigation by early farmers in the Middle East as long ago as 5,000 years ago.
3. THEORY
3.1 THE PUMP UNIVERSE
To understand the peristaltic pump we must first investigate its position within the pump universe. The pump universe can be organized in a variety of ways such as by their design, their material of construction, or the liquids they pump. We will organize the pump universe by classifying the pumps based on the method by which the pump imparts energy to the liquid being pumped. This results in two basic classes of pump: dynamic and displacement. The chart 3.1 shows the basic classification of the pumps.
3.2 BASIC CONSTRUCTION OF PERISTALTIC PUMP
The peristaltic pump is a special type of leak-free rotary displacement pump. Its construction and operating principle are completely different from the other pumps. Basic structure of peristaltic pump is composed of a composite tube or hose element enclosed in a casing and is shown in figure 3.1. The tube or hose has flanges at both ends for connection to the discharge and the suction lines of the system. Fluid flows through the flexible tube or hose fitted inside a circular casing. The casing also contains a rotor that is mounted on a central drive shaft that is supported on its own bearings. The casing also serves as the lubrication chamber and is filled with lubricating oil.
WORKING OF A PERISTALTIC PUMP
Peristaltic pumps work by compressing and relaxing a hose that’s positioned between a rotating device and a circular pump housing. The actual pumping principle, called “peristalsis”, is based on alternating compression and relaxation of the hose or tube, drawing content in and propelling product away from the pump. 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. As the pump’s rotor turns this 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, which 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 peristaltic pump.
PERISTALTIC PUMP TUBING
The tube or hose is the heart of any Peristaltic Pump. A common misconception regarding peristaltic pumps is that the tubing is a major failure point, a maintenance headache for users, and must be replaced every couple of weeks or even days. Another common misconception is that achieving practical tubing life severely limits pumping speed and flow rates because the pump must operate at relatively slow speeds in order to realize adequate tubing longevity. Conventional tubing materials cannot hold up to the harsh demands of certain applications, and the lack of reliable tubing limited peristaltic pump capacities.
3.7 ADVANTAGES
• No contamination. Because the only part of the pump in contact with the fluid being pumped is the interior of the tube.
• Low maintenance needs. Their lack of valves, seals and glands makes them comparatively inexpensive to maintain.
• They are able to handle slurries, viscous, shear-sensitive and aggressive fluids.
• Peristaltic pump is non-siphoning which means that they prevent back flow into the system.
• No cavitation
• Dry running / self-priming / seal less
• Creates high vacuum for suction lift applications
• Pumps in both directions.
• Smooth passage through the pump – no checks or obstructions.
• Accurate flow for metering applications.
• It is easy to sterilize and clean the inside surfaces of the pump.
• Since there are no moving parts in contact with the fluid, peristaltic pumps are inexpensive to manufacture.
• Peristaltic pumps are also reversible and can be flushed to clean out the tubing or hose.
• Same pump could be used to pump other fluids (just change the tube to suitable one)
• The peristaltic pump has a completely disposable fluid path and is self-priming.
• Low Vacuum Force – Peristaltic pumps typically work with soft-walled elastomeric tubing. This tubing is easily compressed but also returns to its initial shape quickly.
• Peristaltic pumps have a gentle, low shear pumping action, ideal for shear sensitive products including flocculants and broths.
• The powerful suction provided by the recovery of a re-enforced hose gives hose pumps suction lift capabilities up to 9.5m of water.
• Peristaltic hose pumps can pump slurries containing up to 80% inorganic solids or 15% organic sludge.
• The pumps have no internal backflow giving accurate dosing without slip.
• The pumps are accurate in dosing, they have a repeatability of ±1% and metering capabilities of ±5%.
• Hose design allows applications to pump aggressive and contaminated fluids.
3.8 DISADVANTAGES
• Tube life is limited.
• Selection of tubes for the required purposes can be sometimes difficult.
• The principal limitation of the peristaltic pump is that its fluid delivery is not absolutely uniform.
• The peristaltic pump can lose its feed rate as it ages, even though the peristaltic has an excellent feed rate earlier on in its operation due to less gassing, which can lead to a feed loss.
• Pumps require frequent calibration to correlate flow rate and pump speed.
• Flow can vary as much as 10-30 percent due to variations in operating pressures.
• Process optimization is difficult since flow for each process step is uncontrolled.
• Uneconomical for long distance pumping.
• Operator needs good knowledge.
• Cannot pump above 10 meters.
5. CONCLUSION
Despite all of the advantages of using peristaltic pumps for corrosive chemicals, they represent only a modest, but ever growing, percentage of the positive displacement pump market. This is primarily because peristaltic technology is relatively new in the market, whereas diaphragm and progressive cavity pumps have a lengthy history. However, to reduce life cycle costs of pumps, the functionality and benefits of peristaltic hose pumps are becoming more widely known, and new peristaltic technology is fast becoming the positive displacement pump of choice for tough chemically aggressive and abrasive applications.