The diaphragm pump sucks and discharges gas by means of the reciprocating motion of the diaphragm in the pump body, so the diaphragm is an important part of the pump body, and its performance has a great influence on the pump. The life of the diaphragm is embodied in several aspects, such as bending life, corrosion resistance, high and low temperature resistance. Therefore, the range of rubber diaphragm materials to meet the above requirements is greatly reduced.
So far, the most widely used and mature rubbers in the diaphragm industry are: EPDM, PTFE, FKM, NBR, etc.:
EPDM rubber
EPDM rubber is a copolymer of ethylene, propylene and a small amount of non-conjugated diene, and the main chain is composed of chemically stable saturated hydrocarbons. It is a common rubber with the lightest raw rubber density.
Anti-aging properties: ozone resistance, UV resistance, and other anti-aging properties. When copolymerized with other unsaturated dienes, the anti-oxidation and anti-aging properties are significantly improved.
Chemical resistance: good resistance to weak acid, alkali, alcohol and ketone; excellent resistance to water and water vapor, radiation resistance;
Insulation: high volume resistivity, breakdown voltage 30 ~ 40MV/m. It can effectively reduce the influence of static electricity caused by friction;
Application areas: widely used in automotive parts, building materials, seals and other fields.
PTFE rubber
Polytetrafluoroethylene, also known as "Teflon", is a polymer compound formed by polymerization of tetrafluoroethylene. It is one of the best corrosion-resistant materials in today's society.
Anti-aging properties: non-moisture, non-flammable, extremely stable to oxygen and ultraviolet rays, and has excellent weather resistance;
Chemical corrosion resistance: It can resist aqua regia and most organic solvents. Even if it is boiled in aqua regia, its quality and performance are unchanged. The corrosion resistance is extremely excellent, but it is not resistant to radiation. It is easy to cause degradation after radiation. The electrical properties 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 material;
Insulation: The breakdown voltage, volume resistivity, and arc resistance are all high, making it an ideal insulating material; applicable temperature: It maintains excellent mechanical properties in a wide temperature range of -196 to 260 °C. It does not become brittle at low temperature and still maintains very good flexibility;
Volume deformation rate: is a typical soft and weak polymer. The mutual attraction between macromolecules has low stiffness, hardness and strength, so it will deform under long-term stress.
Application field: In the petrochemical and metallurgical industry, pipes, pumps, valves and other equipment that need anti-corrosion are widely used. As coating and impregnating materials, they are widely used in textile, medical, chemical, electrical and other fields.
FKM (Fluoroelastomer)
Fluorine rubber is polymerized by fluorine atoms on the carbon bond of the main chain or side chain to form a polymer material. There are many derivatives of fluorine rubber, and the performance varies greatly. This kind of material can be seen in all walks of life.
Aging resistance: excellent weather resistance. It can also be used for a long time in an environment with high ozone concentration;
Chemical resistance: relatively stable chemical properties, resistant to most organic and inorganic solvents and most petroleum-based oils, but not resistant to low-molecular-weight 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 hygroscopicity, good insulation;
Applicable temperature: resistant to a certain high temperature. High mechanical strength can still be maintained at 200°C. But there is a certain volume deformation;
Application field: It is used as a seal in the chemical industry, and can be used to seal various organic solvents. In the petrochemical industry, it is used as an insulating material for wires and cables. It has high oil resistance and wear resistance. It is also widely used in the automotive engine industry.
The above is the selection of rubber diaphragm classification and performance in diaphragm pump accessories introduced by NorthStar. I hope it can be helpful to you. Of course, if you have needs for such as diaphragms, you can also talk with us in detail through the contact information below.