German DoBoTech seals DoBoTech models DoBoTech prices

DoBoTech seals are sealing devices installed to prevent leakage between the pump shaft and the housing. Common types of shaft seals 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.

DoBoTech seal types

1) Squeeze-type seals: Squeeze-type seals, especially O rings, have been widely used in seals. Other types such as X type, T type, D type, square, triangular, etc., are suitable for application in different occasions. The direction of improvement is to make their sealing performance stable and reliable, improve their pressure resistance, and reduce friction. They can also form combined seals with low-friction plastics such as PTFE and nylon slip rings and support rings to improve pressure resistance and reduce friction. Some manufacturers' products are permitted to reach speeds of 7.5m/s and sealing pressures of 5.6MPa. 2) Reciprocating lip seals: Reciprocating lip seals, also known as lip gaskets or cups, are widely used for dynamic sealing in hydraulic system reciprocating cylinders. The pressure-bearing surface of this seal is lip-shaped. During installation, there is a very small interference fit, allowing the lip edge to fully contact the sealing surface to create a seal. When the cylinder operates, as the pressure increases, the contact force and contact area increase, thereby improving sealing performance. During the cylinder return stroke, the pressure decreases, and the contact area and friction are lower than during the working stroke, creating a breathing effect that lubricates the lip. There are many types of reciprocating dynamic seals, commonly including J type, L type, U type, V type, and Y type. There are also various combined and composite seals, such as umbrella-shaped, bud-shaped, and multi-lip seals. Extrusion must be prevented under high pressure by selecting materials with sufficient tear strength, hardness, and modulus, or by using support rings for protection, or by using reinforced elastomers. Seals used under high pressure, high speed, or high temperature often use composite combined seals. Their common feature is having two lips in contact with the cylinder wall. A groove is provided in the middle of the sealing area to store medium, improving lubrication, reducing lip wear, and ensuring reliable sealing. Lip seals used in pneumatic systems are required to operate without oil lubrication; some integrate dust wipers with the seal structure. 3) Rotating shaft lip seals: There are no fewer than 200 varieties of similar structures, such as hydrodynamic type, inner skeleton enclosed, assembled type, outer skeleton exposed, AF type bonded with PTFE, dual-modulus return flow type, etc. The advantage of the outer skeleton assembled type is accurate positioning, high concentricity, and good heat dissipation conditions. It is stable under pressure and vibration, resulting in a longer service life while saving rubber material. The dual-modulus return flow type applies wave seal theory; by adding a low-modulus, easily deformable material at the sealing contact area, a return flow effect is achieved, simultaneously reducing product design and mold processing costs. Flexible sealing treatment should be properly performed at the joints of rigid waterproof layers with gable walls, parapet walls, and structures protruding from the roof.

DoBoTech seal influencing factors

Hydraulic seals play a crucial role in the integrity of hydraulic and pneumatic systems. If the seals of a hydraulic or pneumatic component are not up to standard, the component itself is not considered a good product. Many factors affect seals. First, pressure is an important factor affecting seal quality. The level of pressure and the duration of pressure cycle changes significantly impact seal damage (such as extrusion). The higher the pressure, the greater the impact of other factors on seal performance, such as temperature, speed, seal material, the gap between the piston and cylinder barrel, and the gap between the piston and cylinder head. Another factor is temperature and friction. It is difficult to describe the maximum and minimum operating temperatures for a seal material because this is the result of the combined influence of a series of factors. The operating temperatures for the piston and piston rod are different, so they must be selected accordingly. Another factor is the surface roughness of the seal product. Surface characteristics, pressure, medium, temperature, seal material, seal type, and motion speed are all factors affecting seals. The last factor is surface treatment. Experience shows that the surface characteristics of the cylinder piston and piston rod have a significant impact on seal life. Surface characteristics are commonly defined by the surface roughness value RA, where RA is the arithmetic mean of the absolute values of the surface profile deviations from the centerline. However, these values do not completely represent the impact of surface conditions on seals, because even with the same roughness, different surface shape characteristics can lead to varying degrees of seal wear.

DoBoTech seal installation technical requirements

Mechanical seals are high-precision mechanical components, and their correct installation and operation greatly affect their service life. We generally follow the standards prescribed by the Ministry of Petrochemical Industry. The technical requirements for the pump installing the mechanical seal and the parts mating with the mechanical seal are as follows: 1) Shaft bending: Maximum not greater than 0.05 mm; 2) Rotor runout: Near the shaft sleeve at the dynamic ring seal ring, not greater than 0.06 mm; 3) Axial shaft movement is not allowed to exceed ±0.5 mm. If a shaft sleeve is present, the shaft sleeve must not be loose; 4) Coupling alignment error: For gear couplings, not greater than 0.08–0.10 mm (P2008C); for elastic couplings, not greater than 0.05–0.06 mm; (customary practice: axial runout<0.05, radial runout<0.10) 5) The concentricity tolerance of the gland (static ring seat) and the sealing spigot relative to the shaft centerline is 0.05 mm. The perpendicularity tolerance of the plane contacting the gasket relative to the centerline is 0.03–0.05 mm. If requirements are not met, the seal chamber must be machined; 6) The end of the shaft sleeve where the dynamic ring seal is installed, and the end of the gland (or housing) where the static ring seal is installed, should be chamfered and smoothed. 7) Be careful when installing and removing mechanical seals. Do not use hammers or flat chisels to avoid damaging seal elements. If scale prevents removal, clean thoroughly before disassembly. 8) If mechanical seals are used at both ends of the pump, take care during assembly and disassembly to prevent neglecting one side for the other. 9) For mechanical seals that have been in operation, if gland loosening causes seal movement, the dynamic and static ring parts must be replaced. Do not simply retighten and continue use. Because after loosening, the original running track of the friction pair will change, and the sealing performance of the contact surface is easily compromised.

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