German Merke seals Merke models Merke prices

Merke seals are sealing devices installed to prevent leakage between the pump shaft and the housing. Common shaft seal types include packing seals, mechanical seals, and power seals. The shaft seal of a reciprocating pump is usually a packing seal. When transporting media where leakage is not permitted, a diaphragm reciprocating pump can be used. The shaft seals of rotary pumps (including vane pumps, rotor pumps, etc.) mainly include packing seals, mechanical seals, and power seals. The shaft seal of a reciprocating pump is usually a packing seal. When transporting media where leakage is not permitted, a diaphragm reciprocating pump can be used. The shaft seals of rotary pumps (including vane pumps, rotor pumps, etc.) mainly include packing seals, mechanical seals, and power seals.

Merke seal classification

Oil seals are generally divided into single-piece types and assembled types. Assembled types allow free combination of the skeleton and lip material, and are generally used for special oil seals. Oil seals can be classified into various forms and names based on their sealing function, characteristics, structural type, operating state, and sealing mechanism. However, conventionally, rotating shaft lip seals are called oil seals, while seals used for static sealing and dynamic sealing (generally reciprocating motion) are called seals. The representative form of an oil seal is the TC oil seal, which is a double-lip oil seal with a self-tightening spring fully covered by rubber. The term oil seal commonly refers to this type of tc skeleton oil seal.

Merke seal materials

Common materials for oil seals include: nitrile rubber, fluorine rubber, silicone rubber, acrylic rubber, polyurethane, polytetrafluoroethylene, etc. 1) Nitrile rubber (NBR): It has good heat resistance and wear resistance, and is resistant to various lubricating oils, greases, and oil-gas mixtures. The applicable temperature range is -30~120 degrees Celsius. However, it cannot be used in phosphate ester hydraulic oils and gear oils containing extreme pressure additives. It performs stably in gasoline and mineral oils with low aniline points. 2) Polyacrylate rubber (ACM): It has superior oil and heat resistance, wear resistance, ozone resistance, and UV radiation resistance. It is especially resistant to lubricating oils, gear oils, motor oils, engine oils, and petroleum-based hydraulic oils containing extreme pressure agents. It is suitable for working in the range of -30~150 degrees Celsius. 3) Fluorine rubber: It is resistant to aging, heat, and oil, and is suitable for almost all lubricating oils, fuel oils, and gasoline. It does not easily harden in oils containing extreme pressure additives. However, its cold resistance and high-temperature wear resistance are poor, and it has significant permanent compression deformation. It is suitable for temperatures from -20~250 degrees Celsius. 4) Silicone rubber: It has outstanding high and low-temperature resistance. It can be used super long-term at 150 degrees Celsius without performance change; it can be used continuously at 200 for 10000h. It maintains its unique elasticity, ozone resistance, and weather resistance within the working temperature range of -70~260. 5) Polytetrafluoroethylene: It has outstanding chemical stability, thermal stability, friction reduction, and self-lubrication. Its decomposition temperature is above 400. Therefore, it can work normally in the temperature range of -200~300 degrees Celsius. Except for free fluorine and alkali metals, it has excellent corrosion resistance to chemicals, solvents, hydroxides, and acids. Nitrile rubber and fluorine rubber are widely used oil seal materials. The former is low-cost, but the latter offers significant improvements in temperature resistance and sealing performance. However, the latter is more expensive and still retains some common disadvantages of ordinary rubber materials, such as poor wear resistance, short service life, and high sensitivity to shaft eccentricity. Leakage phenomena are still relatively common. PTFE oil seals are high-tech products and represent the future direction of oil seal development [2]. When selecting oil seal materials, one must consider the compatibility of the material with the working medium, adaptability to the working temperature range, and the ability of the lip edge to follow the high-speed rotation of the shaft. Generally, when an oil seal is working, the temperature of its lip edge is 20~50℃ higher than the working medium temperature, which should be noted when selecting oil seal materials. The working range of an oil seal is related to the material used: for nitrile rubber (NBR), it is -40~120℃; for acrylic rubber (ACM), it is -30~180℃; for fluorine rubber (FPM), it is -25~300℃.

Merke seal precautions

1) Shaft speed: Due to design and structural reasons, high-speed shafts should use high-speed oil seals, and low-speed shafts should use low-speed oil seals. Low-speed oil seals must not be used on high-speed shafts, and vice versa. 2) Ambient temperature: In cases of higher operating temperatures, polyacrylate, silicone, fluorine, or fluorosilicone rubber should be selected. Measures should be taken to reduce the oil temperature in the tank. In cases of lower operating temperatures, cold-resistant rubber should be selected. (3) Pressure: General oil seals have poor pressure-bearing capacity. Excessive pressure will cause the oil seal to deform. Under conditions of excessive pressure, pressure-resistant support rings or reinforced pressure-resistant oil seals should be used. 4) Installation eccentricity: If the eccentricity between the oil seal and the shaft is too large during mating, the sealing performance will deteriorate, which is particularly severe at high shaft speeds. If the eccentricity is too large, oil seals with a "W" shaped cross-section can be used. 5) Shaft surface finish: This directly affects the service life of the oil seal. A higher shaft surface finish results in a longer oil seal service life. 6) Ensure that there is a certain amount of lubricating oil on the lip of the oil seal. 7) Pay special attention to preventing dust from entering the oil seal.

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