Classification, performance, and selection of diaphragm pump diaphragm

Diaphragm pumps are so widely used in some industries that they are almost indispensable. We mainly introduce the characteristics and performance of its diaphragm. Next, please follow us to take a look.

The diaphragm pump inhales and discharges gas by means of the reciprocating movement of the diaphragm in the pump body, so the diaphragm is an important part of the pump body, and its performance has a great impact on the pump. The life of the diaphragm is manifested in several aspects, bending Life, corrosion resistance, and high and low-temperature resistance, so the range of diaphragm materials to meet the above requirements is greatly reduced.

So far, the most widely used and most mature rubbers in the diaphragm industry are the following types: EPDM, PTFE, FKM, NBR, etc.

1. EPDM (ethylene propylene diene monomer)

EPDM rubber is a copolymer of ethylene, propylene, and a small amount of non-conjugated diene. The main chain is composed of chemically stable saturated hydrocarbons. It is a commonly used rubber with the lightest raw rubber density.

Performance Characteristics

Aging resistance properties: Ozone resistance, UV resistance, and other aging properties. The oxidation resistance and anti-aging properties are significantly improved when copolymerized with other unsaturated dienes.

Chemical resistance: good resistance to weak acids, alkalis, alcohols, and ketones; excellent resistance to water and water vapor, and radiation resistance;

Insulation: high volume resistivity, breakdown voltage 30 ~ 40MV/m, can effectively reduce the impact of static electricity caused by friction;

Applicable temperature: The lowest operating temperature is -40~-60°C, which can be used at 130°C for a long time. (The diaphragm material is applicable at this temperature, but it does not mean the pump can also be used. The operating temperature of the pump is affected by the motor, diaphragm, cavity material, and other accessories.)

Application Fields: It is widely used in automotive parts, building materials, seals, and other fields.

2. PTFE (Polytetrafluoroethylene)

Polytetrafluoroethylene, also known as “Teflon”, is a polymer compound formed by the polymerization of tetrafluoroethylene. It is one of the materials with the best corrosion resistance in today’s society.

Performance Characteristics

Aging resistance characteristics: non-moisture absorption, non-flammable, extremely stable to oxygen and ultraviolet rays, and excellent weather resistance;

Chemical corrosion resistance: It can withstand aqua regia and most organic solvents. Even if it is boiled in aqua regia, its quality and performance will not change. It has excellent corrosion resistance, but it is not resistant to radiation. It is easy to cause degradation after radiation. The electrical and mechanical properties are significantly reduced, so the diaphragm used in the exhaust gas sampling pump of the nuclear power plant is mainly made of EPDM;

Insulation: With high breakdown voltage, volume resistivity, and arc resistance, it is an ideal insulating material; applicable temperature: it maintains excellent mechanical properties in a wide temperature range of -196 to 260 ° C and is not stable at low temperatures becomes brittle and still remain very flexible;

Volume deformation rate: It is a typical soft and weak polymer. The mutual attraction between macromolecules and the stiffness, hardness, and strength is small. It will deform under long-term stress.

Note: According to the list of carcinogens by the International Agency for Research on Cancer of the World Health Organization, polytetrafluoroethylene is a Class 3 carcinogen, that is, its carcinogenic effect on the human body is not yet known. It is recommended to take protective measures when using or contacting such materials.

Application fields: In the petrochemical and metallurgical industry, pipelines, pumps, valves, and other equipment that require anti-corrosion are widely used. It is widely used in textile, medical, chemical, electrical, and other fields as coating and impregnating materials.

3. FKM (Fluorine Rubber/VITON)

Fluorine rubber contains fluorine atoms in the carbon bonds of the main chain or side chain to polymerize polymer materials. There are many derivatives of fluorine rubber, and their properties vary greatly. Such materials can be seen in all walks of life.

Performance Characteristics

Aging resistance characteristics: excellent weather resistance, and can be used for a long time in an environment with high ozone concentration;

Chemical corrosion resistance: relatively stable chemical properties, resistant to most organic and inorganic solvents, and most petroleum-based oils, but not resistant to low-molecular ketones, ethers, esters, ammonia, etc.;

Not resistant to radiation, easy to crack after irradiation, and the structural strength has a relatively obvious decline;

Insulation: low moisture absorption, good insulation;

Applicable temperature: resistant to a certain high temperature, and can still maintain high mechanical strength at 200 ° C; but has a certain volume deformation;

Field of application: It is used as a seal in the chemical industry and can be used to seal various organic solvents. It is used as an insulating material for wires and cables in the petrochemical industry. It has high oil resistance and wear resistance. It is also widely used in the automotive engine industry.

For more information, please refer to the user manual of the YINGYI micromodel pump, or contact our engineers for one-step technical support.
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Company Name: Huizhou Yingyi Motor Co., Ltd.
Country: China

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