Structure and operation principle of reciprocating vacuum pump

Reciprocating vacuum pump suction gas pressure is far lower than absolute atmospheric pressure, so it must be operated in the case of large compression ratio

It is generally considered that the clearance of reciprocating vacuum pump must be less than 3%. In order to reduce the influence of clearance gas, the vacuum pump is specially treated in structure. In other words, a balance channel is set on the wall of the vacuum pump. When the exhaust process of the piston is just completed, the balance channel can be connected. Some of the gas in the clearance flows to the other side of the piston to reduce the pressure of the clearance gas and improve the production capacity.

In addition, compared with the reciprocating compressor, the suction valve and exhaust valve of the vacuum pump have smaller opening and closing resistance due to the small pressure difference inside and outside the cylinder, so the sliding block mechanism closely matched with the piston movement can improve the efficiency of the pump

The higher the vacuum degree of reciprocating vacuum pump is, the smaller the absolute pressure of suction pressure is. Therefore, the less air volume can be inhaled in a certain volume of cylinder. Therefore, when the suction volume increases, the vacuum degree will inevitably decrease. In order to maintain a certain degree of vacuum and make the production not affected, it is required that the vacuum pipe system should not leak and the equipment should not leak.

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Common vacuum unit in vacuum furnace plant

Vacuum equipment professional factory provides complete set of vacuum equipment for vacuum furnace and other equipment. In addition to providing a complete set of vacuum acquisition equipment, some of them are also attached with measurement and control vacuum instruments, which can be directly connected to the furnace body. There are many kinds of vacuum units in China, all of them are JK series.

JK series high vacuum unit is generally used for large vacuum furnace. In addition to the units described above, there are oil booster pump and roots pump unit, which are also widely used in vacuum heat treatment furnace.


SSR Roots Type Blowers

Dry Type Oilless Vacuum Pumps

Rotary Vane Vacuum Pump

Material requirements for vacuum system

The materials used in vacuum pump system mainly refer to vacuum pipeline system, valve and sealing material, etc. the materials of vacuum pipeline system include metal, rubber and glass, which have their own characteristics. The type of material to be used depends on the specific situation. The connection between the pipe and the vacuum components can be welded, welded and flanged. The valves in the system are divided into metal valves and glass vacuum taps Species. The sealing materials commonly used in vacuum system include vacuum sealing oil, vacuum sealing wax, vacuum sealing mud, vacuum paint and epoxy resin

In the vacuum system with oil diffusion pump, in order to prevent oil vapor from entering into the pumped system, baffle or cold trap are often used to isolate oil vapor. Dry ice or liquid nitrogen can be placed in the cold trap to condense and absorb the oil vapor in the system, and the vacuum can be further improved.

Water Ring Vacuum Pump manufacturers

Water Ring Vacuum Pump

industrial vacuum pumps,vacuum furnaces

Special vacuum pump for vacuum packaging machine

The main function of vacuum packaging (vacuum packaging) is to prevent spoilage by vacuum packaging, and the main purpose of vacuum packaging is to prevent spoilage of microorganisms, such as vacuum packaging It is to use this principle to take out the oxygen in the packaging bag and food cells, so that microorganisms lose their living environment. The experiment shows that when the oxygen concentration in the bag is less than or equal to 1%, the growth and reproduction speed of microorganisms will drop sharply. When the oxygen concentration is less than 0.5%, most microorganisms will be inhibited and stop breeding. (Note: vacuum packaging can not inhibit the reproduction of anaerobic bacteria and the deterioration and discoloration of food caused by enzyme reaction, so it needs to be combined with other auxiliary methods, such as refrigeration, quick freezing, dehydration, high temperature sterilization, irradiation sterilization, microwave sterilization, salt pickling, etc.)

In the process of vacuum packaging, the general needs of vacuum pump are rotary vane vacuum pump, roots rotary vane vacuum unit, according to the required vacuum degree, the vacuum pump needs to be selected is not the same, can be equipped with the appropriate vacuum pump according to customer needs, if you have questions about vacuum packaging machine special vacuum pump, you can contact us at any time!

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Application technology of oil diffusion pump

Because the partial pressure of the extracted gas above the steam stream is greater than that of the gas in the steam flow, the gas molecules are continuously diffused from the higher pressure area to the lower partial pressure area, and are collided by the supersonic steam molecules. Thus, the gas molecules get a velocity component pointing to the front stage of the pump. From a macroscopic point of view, it seems that the gas molecules are gradually transferred by the steam flow Push down. After several stages of compression, the gas with larger volume and lower pressure has become a gas gap with smaller volume and higher pressure (more than 10-3 Torr) when it reaches the front stage space, and is then pumped away by the front stage mechanical pump. The steam from the nozzle flows to the wall of water-cooled pump, condensed into liquid, flows back to the fractionator, and then heated into steam. In this way, a low pressure area is gradually formed at the upper end and near the nozzle, and the pressure in the container is continuously reduced.

The high-speed steam flow acts as a barrier to the high-pressure and strong gas in the front vacuum chamber, preventing it from returning to the high vacuum end. The high vacuum end pressure of this kind of pump can be generally as low as 10-8 Torr, while the front stage pressure can be higher than the first 10-1 Torr. Therefore, the gas compression ratio is as high as 100 million times, which is also an incomparable advantage of other pumps. However, due to various reasons, the vapor molecules in the pump liquid will inevitably flow back into the high vacuum end and pollute the vacuum system and the evacuated vessels or devices, which must be eliminated.

The efficiency of the pump is more than 50% under the conditions of different pump structure and diffusion mechanism, The maximum working capacity per kW is higher than 1 Torr · L / s, the back pressure of the front stage is better than 0.5 Torr, the limit pressure of direct pumping without cold trap can reach 1 x10-9 Torr, the pumping rate has been increased by two times compared with the old pump, the maximum allowable discharge pressure and durability have been enhanced. Generally speaking, the key problem is that it is possible to obtain ultra-high or extremely high vacuum and "clean" vacuum by oil diffusion pump due to the development of low vapor pressure pump liquid and backflow control. As long as the influence of dissolved hydrogen in materials can be completely prevented, thoroughly baking and degassing, and penetration can be prevented, the pollution caused by the outgassing of materials and pump walls can be reduced as far as possible. It seems possible to obtain the ultimate ultimate pressure of 10-16 Torr with diffusion pump.

Oil Diffusion Vacuum Pump

Dry Type Oilless Vacuum Pumps

SSR Roots Type Blowers

Characteristics of water ring vacuum pump

Water ring vacuum pump can transport both gas and liquid. It is only in the pumping liquid, the aging rate is low. When conveying gas, it can also be used as a low-pressure compressor, and its discharge pressure is about 0.1-0.2 MPa. The range of displacement is 0.25-30 m3 / min. The vacuum degree can reach 70-80%, while the vacuum degree can reach 99.5% when the manufacturing is excellent.

When the extracted gas should not contact with water, the pump can be filled with oil or other liquid medium (at this time, it is often called liquid ring pump). If oil is used as working medium, the vacuum degree of the first stage and the second stage can reach 99.98% and 99.999% respectively.

The biggest advantage of water ring vacuum pump is that it can pump gas containing liquid. In the use of the vacuum system, there are many conditions in which the inhalation contains liquid in the form of clouds. Even if it contains Yanqi state, it will liquefy in the compression process, and it is not suitable to use general reciprocating pump for such suction. Because the liquid is enclosed between the piston and the cylinder head, the valve and other channels become too narrow due to the existence of liquid. The gas resistance increases, that is, the success rate is lost. And the water ring vacuum pump is originally liquid as the piston, so in the suction containing liquid is completely OK.

Water Ring Vacuum Pump

Water Ring Vacuum Pump manufacturers

industrial vacuum pumps,vacuum furnaces

Parameters and classification of vacuum pump

The selection of pumping principle or vacuum pump is limited by specific parameters. These parameters are: minimum pressure, pressure range, pumping speed, exhaust pressure. In the ultra-high vacuum range, there are two other parameters: Pump selectivity and residual gas composition. The exhaust pressure is the pressure that the pump can exhaust under this pressure. According to this point of view, vacuum pumps can be roughly divided into three categories:

1) A pump that exhausts air into the atmosphere. This kind of pump is generally called rough pump or front stage pump. The air in the system is removed to a certain required working pressure, which is called rough pumping of the system. At the outlet of another pump to maintain a required low pressure is called the pre stage pressure. Mechanical rotary pump and jet pump are typical crude pump or pre stage pump.

2) A pump that exhausts only below atmospheric pressure. This kind of pump needs a front stage pump (Shenlian) to exhaust air into the atmosphere. Diffusion pump, roots pump and molecular pump all belong to this type. They all need a front stage pump.

3) A pump that binds the gas and steam in the system. This kind of pump does not need air outlet and is made according to the principle of ionization or absorption.

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