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The peristaltic pump hose is one of the important parts of the peristaltic pump, but users often choose the wrong pipe material, making it unsuitable for the required application. Some users even use ordinary pipes to replace peristaltic pump hoses, causing catastrophic consequences. With the increasing variety of peristaltic pump hoses on the market, it is also more difficult to select pump tubes.

Peristaltic pumps are gaining popularity due to their pollution-free pumping characteristics and the need for less maintenance. However, when designing or purchasing a peristaltic pump system, many engineers often overlook an important component-the peristaltic pump tube.

1. Chemical compatibility

The pipe must be chemically compatible with the fluid to be pumped in order to have good pumping performance and performance. With the increasing number of pipes on the market-some peristaltic pump models have as many as 15 available pipes-so users can always find a suitable pipe that is chemically compatible with a specific fluid.

Many pump tubing suppliers provide chemical compatibility tables. However, engineers must pay attention to the use of a chemical compatibility table specifically designed for pump tubing, not a chemical compatibility table for ordinary pipelines. Because ordinary pipes have only general contact with chemical substances, and peristaltic pump pipes are in contact with chemical fluids under pressure, the chemical compatibility level of ordinary pipes and the chemical compatibility level of peristaltic pump pipes cannot be equal. Therefore, only the pump pipe should be referred to, not the chemical compatibility level of general pipes and related substances, otherwise the pump pipe will fail or break and leak, which will cause damage to the pump or dangerous accidents.

When referring to the chemical compatibility table, the user should check the compatibility of each component of the solution, not only the main component, with the pipe to be used. Certain acids or solvents will cause enough damage to the pump tube even if it is only a small amount after being in contact with the pump tube for several hours or days. The user should check each chemical substance in the solution to ensure that it is compatible with the selected pump tube.

Please also keep in mind that the chemical resistance of the pump tubing decreases as the temperature increases. Although some chemicals do not affect the pump tube at room temperature, when the temperature rises to a certain level, it will cause damage to the pump tube. In the chemical compatibility table, the specific environmental conditions must be indicated, especially the temperature limit, before it can be used to determine the chemical compatibility.

If a chemical substance is not listed in the chemical compatibility table, or if the operating environmental conditions of a factory are too different from the conditions specified in the table, an immersion test can be used to obtain more reliable information. When determining chemical compatibility, if there is no other information to refer to, this method can be used.

The immersion test procedure is as follows: Take a short section of pump tubing, weigh it, and measure its diameter and length. Then put the pump tube into a closed container filled with related chemicals and soak for 48 hours. Take out the tube, wash and dry, weigh and measure the size, and record the change of the two measurements before and after. The pump tube should also be checked for signs of softening or embrittlement, which indicate that the chemical substance has harmed the pump tube. After pre-selecting one or several kinds of pipes, the pumping test can be carried out. Each candidate pump tube sample should be put into the factory's actual environmental conditions for trial operation, and the test results should be closely observed. If the pump tube does not show discoloration, swelling, cracks, loss of fluidity, or other signs of deterioration after trial operation, it is proved that it is compatible with the fluid.

Please keep in mind that in order to select the right pipe, whether it is to consult the compatibility table, to do a physical test, or to use both methods, the responsibility should be borne by the user. Only meticulous analysis and testing can ensure the correct test results.

The chemical compatibility of different pipes and solutions varies greatly. But there are also some materials that have super resistance to most chemicals. For example, Viton fluororubber pump tubing can resist a variety of inorganic chemicals and even some organic chemicals. For another example, polytetrafluoroethylene (PTFE) pump tubing is compatible with almost all chemical substances. However, the PTFE pump pipe is a rigid pipe, which requires a pump head. When pumping a variety of corrosive chemicals, pipes that can resist multiple chemicals should be the choice.

2. Pressure

The emergence of high-pressure pump tubing expands the application range of peristaltic pumps to new application areas, including filtration.

The pressure source of a fluid delivery system can vary. When the fluid is pushed through a filter, or the fluid is pushed through a flow meter or valve, or the fluid is pumped into a pressurized reaction vessel, back pressure is created. Before selecting the pipe, the user should first make sure that all the pressure sources in the system have been clarified and the actual measured value of the total pressure of the system has been obtained. When selecting the pump tubing for the peristaltic pump, the user should ensure that the pressure in the system does not exceed the recommended working pressure of the pump tubing. If the pressure is too high, the pump tube will swell and fit poorly with the pump head, resulting in rapid wear and failure. When the system pressure greatly exceeds the bearing capacity of the pump tube, the pump tube may even burst and spray fluid. After selecting a pipe material, ensure that the pressure is maintained within the pressure range recommended by the manufacturer when using it. If the system exceeds the working pressure, a simple pressure relief valve or pressure switch can be installed to prevent the accumulation of excessive pressure. The function of the pressure slow release valve is: when the system pressure exceeds the set value, it will vent to the atmosphere to reduce the system pressure to a level. A more complicated pressure switch can also be used. When the pressure value exceeds the set value, it will turn off the equipment or sound an alarm device through a relay.

3. Temperature

The operating temperature range of the pump tubing is another important factor to consider. Some pipe materials, such as silicone rubber, have a wide temperature tolerance range and are suitable for both high and low temperature processes; while some pipe materials such as Tygon and C-Flex are only suitable for a small temperature range. Before selecting the pipe, the user should first find out the maximum temperature and the minimum temperature in the system, and then ensure that the selected pump pipe works in this temperature range. In applications where the temperature needs to be gradually increased, the user should consider the effect of temperature on the chemical resistance and pressure bearing capacity of the pump tube. When the temperature increases, the pressure bearing capacity of the pump tube will decrease.

Four, size

As each roller in the pump head presses through the pump tube, the peristaltic pump will pump a certain amount of fluid. Therefore, the size of the pump tube is directly related to the pumping flow, that is, it has a great impact on the operation of the fluid delivery system. The pump tube is the part that needs to be considered when designing a high-quality peristaltic pump. The size or size range of the pump tube needs to be calculated. The size here mainly refers to the inner diameter and wall thickness of the pump tube. The inner diameter determines the amount of fluid pumped per revolution of the rotor, and the thickness of the wall determines the ability of the pump tube to restore its original shape after each rolling. This ability greatly affects the service life of the pump tube. If the size of the pump tube is too small relative to the size of the pump head, the pump head will not be able to lock the pump tube, and the pump tube will be pulled out of the pump head; and the pump tube size is too small, the rollers in the pump head cannot hold the pump tube, so Will cause insufficient pumping flow or complete failure. If the size of the pump tube is too large, the excess tube will produce wrinkles between the roller and the pump casing or between the roller and the occlusal bed, resulting in rapid wear and premature failure. When selecting the size of the pump tube, the user should follow the manufacturer’s recommendations to ensure that the system functions well. In some applications that require higher accuracy (such as chemical dosing pumps), the role of pump tube size is more prominent. A slight deviation in size will result in a large deviation in flow or distribution amount and unqualified. Although the size of pump tubing provided by some manufacturers is "close" to the recommended size and "looks the same", there is often a gap. Therefore, in order to achieve the performance and working accuracy of the pump system, the user should use the pump tube size that is exactly the same as the size recommended by the manufacturer.

Five, tolerance

Tolerance is the allowable error of the pump tube size. The smaller the tolerance, the smaller the performance deviation of the pump tube, and the better the consistency and repeatability. The larger the tolerance, the more unstable the performance of the pump tube. Some pump tubes have very small manufacturing tolerances, and their dimensional deviations are strictly controlled during extrusion. Although it is slightly more expensive to manufacture pump tubing with smaller tolerances, it is worth the cost compared to the improvement in pumping performance.

Six, the average life of the pump tube

Peristaltic pumps face harsher conditions, so pipes with better intrinsic quality, especially those with better resilience, will have a longer service life. In the long run, the longer the service life of the pipe, the lower the operating cost. The fewer pump tube replacements, the less maintenance costs and downtime. The less likely the pump tube will leak and burst. In short, the longer the service life of the pump tube, the lower the total pumping cost. The pump tube manufacturer shall provide test data to prove its claimed pump tube life. Some manufacturers have published relevant information in their manuals (such as "Cole-Parmer Instrument Company Masterflex Pump Information". In any case, when designing a system, engineers should have some understanding of the average life of pipes, so as to help users formulate preventive measures. Maintenance plan so that the pump tubing can be replaced before it fails. Pump tubing suppliers with rich technical knowledge can provide users with useful information for specific applications in order to select suitable pump tubing materials.

7. Transparency

Whether a transparent pipe should be used depends on whether the operator needs to observe the condition of the fluid in the pipe at any time, and also whether the fluid is sensitive to light. If the operator needs to observe the fluid, bubbles, particles, pollution, etc. in the pipe at any time, he should use transparent pipes such as Tygon polyethylene or silicone rubber; and if the solution is not suitable for exposure, opaque pipes should be used

8. Air permeability

For some gas-sensitive fluids, such as fluids that are susceptible to oxidation, or anaerobic cell culture fluids, users should consider the air permeability of the pipeline. In general, the air permeability of the silicone tube is high. Therefore, for fluids that are not suitable for contact with gas, pipes with lower air permeability should be used.

Nine, regulatory approval

For the pharmaceutical industry, regulatory certification is essential. In this industry, every item in contact with the product must meet specific standards and guidelines. For this reason, many pump tubing materials are developed in strict accordance with regulatory requirements. These regulations include the United States Pharmacopoeia (USP), the European Pharmacopoeia (EP), the United States Food and Drug Administration (FDA), the United States Department of Agriculture (USDA), and the National Sanitation Foundation (NSF). Of course, it is not enough to just claim that certain materials comply with certain regulations. The pump pipe manufacturer shall provide the user with a certificate proving that the pipe complies with the regulations according to the user's requirements. In this way, the user can provide the necessary certificates to prove that the pump system complies with the necessary regulatory approvals.

10. Cost

Cost is almost a factor that needs to be considered when formulating every project plan. Just as when selecting other components, the user should evaluate the overall cost of use of the alternative pump tubing. For example, a certain type of pump tubing costs US$2 per foot and needs to be replaced every 500 hours; while another type of pump tubing costs US$1 per foot and needs to be replaced every 100 hours; the former is more cost-effective than the latter. Sudden rupture of low-quality pump tubing can cause loss of valuable fluid or damage to the pump, resulting in high-cost downtime and extensive repairs, or even replacement of the entire pump. Therefore, cheap pump tubing is not necessarily an economical choice. It seems impossible to pick an ideal pump tube in the wide variety of pump tube market. However, as long as you carefully study the system requirements, refer to the relevant technical indicators, and maintain close communication with the pump tube manufacturer or supplier with application knowledge and experience, you can select the pump tube suitable for the relevant pump system.

As two kinds of equipment for precision fluid transmission, syringe pump and stab pump are used more instruments. Due to the wider application industry, its models are also diverse. Some users are often unable to distinguish what to pay attention to when selecting the two types of equipment and what the difference is when using this equipment. The following will explain for you.

The difference in working principle of laboratory syringe pump and peristaltic pump

The difference in working principle lies in the different ways of entering auspiciousness between the two. The syringe pump is used to inject and extract the liquid through the movement of the plug (injection and then extraction, first extraction and then injection, continuous circulation): generally more accurate than peristaltic pumps , The operation is simpler. The peristaltic pump uses a roller to squeeze the silicone tube of the peristaltic pump, and uses the elasticity of the hose to promote the pressure at the inlet of the silicone tube to show a negative pressure, so that the liquid is filled with the silicone tube to achieve the purpose of transporting the liquid.

The difference between the two selections

Syringe pump syringe: It is one of the main components of the syringe pump. Before choosing, you must know the amount of liquid you need to inject, how many milliliters you need to inject at a time, and then determine the specifications of the syringe.

Driver: Determined according to the wave body that needs to be transported and the function mode that needs to be used. For example: the distribution mode of the liquid, under what environment it is used, multi-channel injection or single-channel injection, whether there is a requirement for liquid flow rate, and what is the accuracy of each injection. Peristaltic pump flow selection: Flow is one of the important elements for selecting pump models. Different flow rates correspond to different pump heads and hoses.

Silicone tube selection: There are many kinds of hoses used in the motion pump, most of the transmitted wave body can be used to beat the pump silicone tube, but some liquids have special chemistry, so you must look at the liquid when you choose. Chemical properties, liquid temperature and requirements for suction range.

Peristaltic pump pump head: The pump head is also more important as one of the three major components of the peristaltic pump (the other two are the driver and the hose). When selecting the pump head, in addition to paying attention to the flow rate mentioned above, you should also consider replacing the silicone tube. Whether it is convenient, whether there is a need for multiple channels, whether there are special requirements for the working environment, etc.

Drive: Drive is the power component of the pump. The higher the speed, the larger the flow. This is different from syringe pumps because their working principles are different. The driver on the peristaltic pump needs to pay attention to whether some special functions are needed, such as speed adjustment, flow adjustment, distribution mode, etc. Another point is similar to the syringe pump, that is, the requirements of the working environment, whether there are requirements for dust, water, explosion and explosion.

How to improve the service life of peristaltic pump

1. Loosen the pressure block when the pump is not working can prolong the life of the pump tube. The pump uses the peristaltic pump head rollers to repeatedly squeeze the hose and the natural rebound of the hose to produce suction to achieve fluid delivery. If you want to maintain the longevity of the pump tube, when the pump is not in use, try to lift the pressure block of the pump head to make the pump The tube is in a natural uncompressed state, thereby prolonging the life of the pump tube.

2. When selecting the model, under the premise of meeting the requirements of the customer's meteor, the pump speed should be reduced to less than 300 revolutions as much as possible. The meteor of the peristaltic pump is produced by the rotation of the pump head roller. The faster the rotation, the shorter the service life of the pump tube. When you want the pump tube to be used for a longer time, you can choose a relatively large tube diameter to reduce the pump.的rpm。

3. Dart-moving pump pipes are used on the pump head, and ordinary constant-flow pump pipes are used for the other connecting pipes. Extrusion tubes used in peristaltic pumps require good compression, resilience, and tear resistance. Therefore, the material purity of these pump tubes is relatively high, and the wall thickness and shape accuracy are high, which will result in higher prices for peristaltic pump tubes. Therefore, the peristaltic pump adopts pipes to ensure the service life, and the connecting pipes use ordinary pipes, which makes the whole system more economical and applicable.

The peristaltic pump is used to obtain the required flow rate. Therefore, according to the operation and use of the pump, it is divided into: 1. Speed-regulating peristaltic pump: It has the basic control function of the peristaltic pump, displaying the speed, start and stop, direction, speed adjustment, and filling row. Empty, power-down memory, external control input and other functions.

1. Classification

The peristaltic pump is used to obtain the required flow. Therefore, according to the operation and use of the pump, it is divided into:

1. Speed-regulating peristaltic pump: It has the basic control functions of a peristaltic pump, displaying speed, start and stop, direction, speed adjustment, filling and emptying, power-down memory, external control input and other functions.

2. Flow-type peristaltic pump: In addition to basic functions, functions such as flow display, flow correction, and communication are added.

3. Distributed peristaltic pump: In addition to basic control functions, it adds functions such as flow display, flow correction, communication, liquid volume distribution, suction, and output control.

4. Customized (OEM) peristaltic pump: With a series of pump heads with different flow ranges, customers can design different drive circuits for supporting use according to their own equipment requirements.

2. System composition

The peristaltic pump system consists of three parts: the peristaltic pump driver, the peristaltic pump head, and the peristaltic pump tube.

Third, the selection of the components of the peristaltic pump

Selection tube

       As a condition of peristaltic pump hose
       Has a certain degree of flexibility, that is, the hose can quickly recover its shape after being compressed in the radial direction
       Have a certain ability to withstand pressure
       No leakage (good air tightness)
       Low adsorption, good temperature resistance, not easy to age, no swelling, corrosion resistance, low precipitation, etc.

Choose pump head

       Choice of single or multi-channel fluid delivery
       Is it easy to replace the hose
       Is it easy to fix the hose
       The pressure tube gap is fine-tuned by a ratchet or other means to adapt to different wall thickness hoses or to achieve fine-tuning of pressure
       Roller selection: 6-roller structure has a slightly larger relative flow rate; 10-roller structure has a smaller fluid pulsation amplitude
       Whether the trigger structure is dexterous and whether it is convenient to open the card

Select drive

       Do you need flow control
       Do you need liquid volume distribution
       What is the size of the flow range
       Whether the overall structure is reasonable and whether the operation is convenient
       Whether the flow accuracy and liquid volume accuracy meet the requirements
       Special requirements: protection level, explosion-proof level, etc.
       External control requirements: Peristaltic pump equipment matching, operation mode, etc., such as RS232, RS485 communication, 0-5V external control speed regulation, pulse speed regulation, etc.

Seeing that the Baidu index of peristaltic pumps is getting larger and larger, it also reflects that the search volume of our peristaltic pumps is getting larger and larger, which can reflect that the demand for peristaltic pumps is constantly increasing, so what factories are there? Can a peristaltic pump be used? What is the application range of peristaltic pumps? Today we will discuss this issue.

Question: What caused the increasing demand for peristaltic pumps?

Answer: A peristaltic pump is a liquid transfer device. First of all, advances in science and technology will cause the demand for peristaltic pumps to increase; secondly, the improvement of people's quality of life will cause the demand for peristaltic pumps to increase. With the development and progress of the times, the demand for peristaltic pumps will become larger and larger, and the corresponding requirements for the quality of peristaltic pumps will become higher and higher.

Question: So what are the applications of peristaltic pumps?

Answer: First of all, from the perspective of scientific and technological progress, peristaltic pumps will be used in the research and development of university laboratories, research and development of packaging boxes, enterprise laboratories, etc. People have been conducting continuous research and development, so in this regard, peristalsis The application range of the pump is very wide, so the demand for the peristaltic pump will be enlarged. Then, from the perspective of improving people's quality of life, peristaltic pumps will be used in environmental protection agriculture and other analysis and packaging to further improve product efficiency and improve product quality. From this perspective, some products will use peristaltic pumps for the improvement of people's quality of life, so from this perspective, the improvement of people's quality of life will drive the development of peristaltic pumps.