German HAHN seals HAHN models HAHN prices

HAHN seals are typical representatives of oil seals; the term "oil seal" generally refers to skeleton oil seals. The function of an oil seal is generally to isolate components requiring lubrication in transmission parts from the external environment, preventing lubricating oil leakage. The skeleton acts like rebar in concrete components, providing reinforcement and enabling the oil seal to maintain its shape and tension. According to structural form, they can be divided into single-lip skeleton oil seals and double-lip skeleton oil seals. The secondary lip of a double-lip skeleton oil seal serves as a dust seal, preventing external dust, impurities, etc., from entering the machine interior. According to skeleton type, they can be divided into inner-covered skeleton oil seals, exposed skeleton oil seals, and assembled oil seals. According to operating conditions, they can be divided into rotating skeleton oil seals and reciprocating skeleton oil seals. Used for gasoline engine crankshafts, diesel engine crankshafts, gearboxes, differentials, shock absorbers, engines, axles, and other locations.

HAHN seal classification

1) Packing seal: The packing seal features a simple structure, low cost, and easy maintenance. However, it has high leakage volume and significant power loss. Therefore, packing seals are used for transporting general media, such as water; they are generally not suitable for petroleum and chemical media, especially for valuable, flammable, explosive, or toxic media. 2) Mechanical seal: A mechanical seal (also known as a face seal) provides good sealing performance with minimal leakage and long service life, but it is expensive and has higher requirements for machining, installation, maintenance, and repair compared to general seals. Mechanical seals are suitable for transporting petroleum and chemical media and can be used for media with various viscosities, strong corrosiveness, and particulate content. The American Petroleum Institute standard API610 (8rd edition) stipulates that cartridge mechanical seals shall be installed unless otherwise specified by the user. 3) Dynamic seal: Dynamic seals can be divided into two types: back-vane seals and auxiliary impeller seals. During pump operation, the centrifugal force of the back vanes (or auxiliary impeller) reduces the medium pressure at the shaft seal to atmospheric or negative pressure, preventing leakage during use. When the pump stops, the centrifugal force disappears, and the sealing effect of the back vanes (or auxiliary impeller) fails; at this point, the shutdown sealing device provides the sealing function. Packing seals are commonly used in the shutdown sealing devices associated with back-vane (or auxiliary impeller) seals. There are two types of packing seals: standard type and mechanically adjustable tension type. Standard packing seals are similar to those in general packing-seal pumps and require maintaining a slight positive pressure at the shaft seal to avoid dry friction of the packing. Mechanically adjustable tension packing seals use counterweights to loosen the packing during pump operation and tighten it when stopped. Dynamic seals offer reliable performance, low cost, and easy maintenance, making them suitable for transporting media with a high content of solid particles, such as slurry pumps and ore pulp pumps in the phosphate industry. The disadvantages are greater power loss compared to mechanical seals and shorter service life of the shutdown sealing device. The seal between the rotating pump shaft and the stationary pump casing is called the shaft seal. Its function is to prevent high-pressure liquid from leaking out of the pump along the shaft or outside air from infiltrating along the shaft. For centrifugal pumps, the shaft seal is a type of dynamic seal. Depending on whether the sealing surfaces are in contact, dynamic seals can be classified as contact dynamic seals and non-contact dynamic seals. In contact dynamic seals, the sealing device contacts the shaft, resulting in relative friction between the two. Contact dynamic seals include packing seals and mechanical seals.

HAHN seal operation

1) If slight leakage occurs after the pump starts, observe for a period. If the leakage volume does not decrease after continuous operation for 4 hours, stop the pump for inspection. 2) The pump operating pressure should be stable, with pressure fluctuations not exceeding 1 kg/cm². 3) During pump operation, avoid cavitation to prevent dry friction of the sealing faces and seal damage. 3) Check the sealing condition frequently. During operation, if leakage exceeds the standard, heavy oil shall not exceed 5 drops/min, and light oil shall not exceed 10 drops/min. If there is no improvement trend within 2-3 days, stop the pump to inspect the sealing device.

HAHN seal specifications and applications

1) Standard single-lip type: Generally used for sealing mineral oil, water, and other media on high- and low-speed rotating shafts and reciprocating motion. Standard oil seals are used in environments with less dust and impurities, resistant to medium pressure< 0.05MPa, maximum linear speed 15m/s, reciprocating speed< 0.1m/s. 2) Standard double-lip type: In addition to the usage characteristics of the aforementioned S type oil seals, it also provides dust protection. Standard oil seals with a dust lip can prevent dust ingress, resistant to medium pressure< 0.05MPa, linear speed ≤ 15m/s. 3) Springless type: Springless single-lip inner-covered skeleton rubber oil seal. Generally suitable for low-speed conditions where the sealing medium is lubricating grease. Linear speed ≤ 6m/s. 4) Outer skeleton single-lip type: Single-lip exposed skeleton rubber oil seal with spring, featuring a thin waist, good followability, and good rigidity. Standard oil seals are used in environments with less dust and impurities, resistant to medium pressure< 0.05MPa. For cases where the rotating shaft linear speed ≤ 15m/s. 5) Outer skeleton double-lip type: Double-lip exposed skeleton rubber oil seal with secondary lip, featuring a thin waist, good followability, high rigidity, and good coaxiality. Standard oil seals with a dust lip can prevent dust ingress, resistant to medium pressure< 0.05MPa. Rotational speed ≤ 15m/s. 6) Assembled single-lip type: Outer skeleton oil seal formed by assembling inner and outer skeletons with rolled edges, featuring high installation precision, fast heat dissipation, and heavy-load characteristics. Suitable for heavy-load conditions under high temperature and high speed, medium pressure ≤ 0.05MPa, maximum linear speed ≤ 15m/s. 7) Unidirectional return flow type (right-hand, left-hand): Angled ribs are manufactured on the air side of the lip, utilizing fluid dynamics principles to generate a unidirectional pumping action with a return flow effect. Related to the shaft rotation direction, the radial force is smaller than that of standard oil seals due to the return flow effect, reducing wear and heat generation, and extending service life. Suitable for medium pressure< 0.05MPa, rotational speed ≤ 20m/s. 8) Pressure-resistant type: Short lip and short, thick waist, providing pressure resistance, working pressure ≤ 3MPa. Suitable for applications with medium pressure ≤ 3MPa, suitable for shaft end oil seals of high-pressure pumps; generally, the PV value ≤ 8. Rotating shaft linear speed ≤ 15m/s.

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