How to choose a diaphragm pump: tips and reviews. Types of diaphragm pumps

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Pumps are units that are widely used in various industries, as well as in solving some problems in everyday life. There are many varieties of this type of device. Diaphragm pumps are among the most popular and practical in use. Their popularity in Russia is growing. What are their design features? What are the advantages of such pumps? What should be considered during their operation?

How the pump works

How does a diaphragm pump work? The scheme is this. This device consists of two cavities placed one opposite the other. They are separated by a membrane - a very flexible, but at the same time strong plate. One cavity is filled with air, the other with liquid. Between them, in turn, is a distributor that acts on the membrane so that it moves back and forth with a small amplitude.

As a result, a certain volume of fluid is displaced from one cavity, and absorbed into the other. When the membrane occupies the opposite position - the substance moves in the horizontal plane - due to the presence in the structurespecial valve assembly. The diaphragm pump thus operates on the principle of substance displacement - as, indeed, piston-type devices. But in the latter, as a rule, there are no flexible parts like a membrane. The manufacturing scheme of the unit guarantees high stability of the device.

Due to the design features, the diaphragm pump chamber is practically not contaminated. In this regard, this kind of devices in the course of practical operation behave more reliably than traditional piston ones. Diaphragm pumps are best suited for pumping water, liquids with increased density and viscosity, and slurries.

Materials of construction

The pump diaphragm is usually made of rubber or flexible and extra strong steel grades. In turn, the body of the device is usually made of materials that are resistant to corrosion and chemicals (if the appropriate specifics of their use are assumed). The supplied liquids or slurries are sent to the pressure pipeline, which is also most often made of rubber or PVC.

Benefits of Diaphragm Pumps

The diaphragm pump has a number of advantages. First, it is the exceptional ease of execution (in most technological implementations). As a rule, in units of this type there are no rotating parts and engines. Those mechanisms that set the pumps in motion are not technologically sophisticated devices. As a rule, modern diaphragm pumps - withan electric drive of a fairly simple design, with a pneumatic system, or even a manual move. Secondly, these units operate with a minimum probability of failure - in fact, this property of them is due precisely to the simplicity of the design. The diaphragm pump is a device that will last a long time. Thirdly, these devices are very easy to install and assemble, not demanding on storage and transportation conditions. Temperature, air humidity and other environmental factors practically do not affect the functionality of the pumps.

Technological executions

The units in question are different. Among the most common is the pneumatic pump. A membrane unit of this type operates without the participation of an electric drive, other complex transmission devices and equipment elements. Such a device is especially convenient in terms of transportation. Other noteworthy properties include the absence of noticeable heating, as well as tightness, which in some cases allows the device to be used under water. As we noted above, there are electrically driven diaphragm pumps. They are also quite common due to their versatility (they are adapted to most electrical systems used in Russia), high performance, and reasonable prices. There are also hydraulically driven pumps.

Thus, the main criterion for classifying devices is the type of motor. In general, the principle of operation of each type of device is the same: a membrane (or, as it is also called, a diaphragm)bends under the influence of a mechanical motor, air (in the case of a pneumatic drive) or water (in the case of a hydraulic system), as a result of which the movement of the supplied substance is ensured. Some pump designs have two diaphragms. Compressed air acts on one, as a result of which it bends, advancing the supplied substance to the outlet valve. At the same time, in the area where the second membrane is located, a vacuum is formed, into which, due to natural physical laws, the substance is absorbed. And so with every movement of the drive. Two membranes in this case are connected by a mechanical shaft. Air valves that operate automatically also participate in the transfer of the substance. Thus, two processes take place in the pump - suction (when the first membrane rarefies the air when moving from the walls) and injection (when the second diaphragm transfers the pressure of the pneumatic flow to the liquid that has managed to get into the housing, thereby ensuring the movement of the substance to the outlet). The pressure indicators in the region of the back wall of the membrane that releases the liquid, and the one located at the inlet area, are thus equal. Often the unit in question has a different name - "vacuum pump". The membrane mechanism is present in all technological implementations of the device. The reason for this is its simplicity and, at the same time, high efficiency. As for double diaphragm pumps, they are usually pneumatic.

Pump efficiency criteria

Based on what criteria are diaphragm pumps evaluated inaspect of efficiency and quality of work? Experts identify the following set of parameters.

Firstly, a pneumatic diaphragm pump (or one equipped with an electric drive) must operate smoothly without the need for repairs, additional adjustments, lubrication and other procedures that require production resources.

Secondly, units of this type must be environmentally friendly. In principle, this criterion is met in relation to most modern models of diaphragm pumps. Not many devices run on petrol or gas, for example.

Thirdly, it is desirable that there is a workable and easy-to-use system for regulating the speed and volume of substances supplied. That is, the pump should not work only in the "on" and "off" mode. It is necessary to be able to adjust the suction intensity to the type of substance and the task being solved in production.

Fourth, the design of the pumps must be such that if solid objects get inside the cavities, this does not lead to mechanical damage to the device and its breakdown.

Also, some technical experts consider it important that pumps have a surge protection system (if we are talking about electric units), as well as efficiency - regarding the same type of devices.

Scope of application

There are several classes of appliances in question. There is a dosing diaphragm pump, manual, vacuum - and all of them are successfully used in a variety of industries. As a rule, thisindustry - oil and gas, food, paint and varnish. chemical, as well as construction. Gradually, devices are being mastered by private individuals - in farms, for example. Miniature devices are becoming quite popular. In particular, some of them can consume quite a bit of electricity (despite this, the user will have a full-fledged membrane pump in their hands) - 12 volts. Such devices are often used by summer residents to design irrigation systems or a small water supply system. Reviews of many homeowners characterize small household diaphragm pumps exclusively on the positive side.

These mechanisms, especially those adapted for use in industry, can be pumped by a variety of substances - water, liquids with a higher density and viscosity, as well as those that allow solid inclusions (depending on the modification of the device, their allowable size varies from millimeters to several centimeters). Some models are adapted for pumping chemically aggressive substances.

Dosing pumps

There is a subtype of the units we are considering - dosing pumps. Membrane mechanisms in them, in principle, are the same as in conventional devices of this type, however, the range of their purpose, as a rule, is narrower. Many models of devices are adapted to work just the same with chemically active substances - when there is a need for their periodic dosage.

What are their design features? Diaphragm metering pumpsas a rule, precision, with exceptional tightness of the case. Their productivity (intensity of pumping of substances) is very flexibly regulated. At the same time, modern models provide options for setting the necessary parameters - both in the mode of the current operation of the unit, and in the process of pre-configuration. Depending on the design and technological type of the device, this can be done manually or using drive elements.

Among the notable features of metering pumps is their particular ease of maintenance. In particular, they are designed, as a rule, in the form of blocks - this causes simplicity and minimal labor costs when assembling or installing devices. Such pumps are usually equipped with valves adapted to the hazardous media. This is especially important as these elements are quite sensitive.

Dosing-type devices have a fairly large number of strokes (movements) - about 100-150 per minute. At the same time, you can adjust the amplitude - in modern models this can be done using the interval 0-100%.

In some cases, the specifics of production involves the use of a "hybrid" model of devices. Namely: a diaphragm-piston pump may be required. It combines the advantages of diaphragm, as well as "classic". Consider the specifics of this type of aggregates.

Features of piston diaphragm pumps

As such, the vacuum pump (diaphragm), due to the design features, is not alwaysDesigned for handling high density materials. In addition, according to some technical experts, its efficiency is not always optimal. Therefore, it is advisable to use a pump that has the characteristics of both a diaphragm and a piston. This type of device in many cases operate with higher efficiency and lower energy costs.

In addition, the scope of piston diaphragm pumps, as a rule, is wider than that of diaphragm pumps. In particular, they can be used not only for pumping liquids, but also for moving sludge, in filter presses, as part of the design of spray dryers. Some hydraulic type piston diaphragm pumps can also be used in the mining industry, in thermal power plants, in the ceramic industry, in metallurgy. Thus, devices of this type, having the advantages inherent in both membrane and piston versions, are more versatile in many modifications. That is, if diaphragm devices are more adapted for pumping liquids (with a certain percentage of solids), then "hybrid" ones can quite cope with the movement of substances, in which, in turn, the concentration of insoluble elements can be higher.

However, this type of units are usually much more expensive than piston or diaphragm units separately. However, with proper optimization of the production process, the costs can pay for themselves. In addition, energy costs, due to the more efficient efficiency of "hybrid" pumps, are less -at least in this part of the business costs will be reduced. Also, due to the design features of piston diaphragm pumps, the wear of parts on them is often lower than when using diaphragm devices.

How to choose a pump?

Based on what criteria should a diaphragm pump be selected (if it is a device that is not a hybrid type)? The key parameters that can indicate the performance of devices of this type are as follows:

- pressure at the outlet valve (in most cases, the minimum figure should be 60 bar - but it all depends on the intended area of \u200b\u200buse of the pump);

- suction height (preferably at least 4-5 meters);

- intensity of substance supply (measured in cubic meters per hour - the range of recommended parameters is very different - from 0.5 to tens of units, it all depends on the purpose of the device);

- distance of pressure transfer (duration of the pipe through which the substance is supplied - at least 50 meters);

- compressed air pressure (as a rule, in the range of 0, 2-0, 6 MPa, but there may be other values);

- allowable temperature range of pumped substances (usually 0-80 degrees);

- the diameter of the holes at the inlet and outlet, as well as where the air is supplied (indicated in centimeters or inches - usually for imported models);

- limiting diameter of solid inclusions (may vary from a few millimeters to centimeters).

At the same time, the classification of pumps and the range of their purpose are so extensive thatthe selection of optimal parameters when choosing this type of device will always depend on the specific scope of their application.

Flaws

The device in question has plenty of advantages. This is versatility - a diaphragm pump can be used for water and a large number of other liquids with different physical properties. This is environmental friendliness - as a rule, drives without emissions and gases are used in the design of devices. This is the breadth of technical performance - there is an electric, hydraulic, pneumatic, manual diaphragm pump. But it should also be said about the shortcomings that are characteristic of units of this type.

Firstly, the pump diaphragm or diaphragm is in motion all the time. This eventually leads to wear and tear - they become less airtight, or even completely fail. But, as a rule, modern equipment manufacturers attach several spare membranes to the supplied kit, and if they run out, you can always order new ones. For example, the HBM company, supplying its flagship product - a vacuum diaphragm pump (HBM specializes in such devices), supplements the kits with spare parts.

Secondly, due to the intensity of operation, the valves of the devices also wear out. Also, in some cases, they may become clogged with solids that are present in the supplied liquids. However, they can also be replaced.

Some difficulties in the operation of pumps may be due to the periodic appearance of vapor locks at the time of suction of the liquid (ifSubstances with a high vapor pressure are being processed, such as methyl chloride).

At the same time, the noted three shortcomings are compensated by the high maintainability of the pump, as well as the ease of replacing worn parts. In addition, in order to minimize the likelihood of damage to membranes and valves, various types of damping devices can be used simultaneously with the units (and in some cases, as part of their design), designed to smooth out impulses resulting from the movement of diaphragms. Anyway, diaphragm pumps are preferable to use than their traditional counterparts. The economic profitability of many industries is often predetermined by the ability to use just such units.