How to replace the mechanical seal

Mechanical seals use mechanical means to transmit power and motion. Mechanical transmission is widely used in mechanical engineering and has many forms, including belt drive, gear drive, chain drive, worm and worm gear drive, rack and pinion drive and screw drive, etc. . Gear transmission can be used in high-power applications, and the transmission ratio is accurate, but generally requires higher manufacturing accuracy and installation accuracy. There is also a type of friction drive that transmits power and motion by the friction between the parts, including belt drive, rope drive and friction wheel drive. Friction transmission is easy to realize stepless speed change, which can adapt to transmission occasions with large shaft spacing, and overload and slip can also play the role of buffering and protecting the transmission device, but this kind of transmission can not generally be used in high-power occasions, nor can it guarantee accuracy transmission ratio.

There are many transmission forms, but the replacement of the mechanical seal is similar. Before dismantling, it is necessary to confirm that the motor is in the maintenance state, unscrew the oil plug, and use a suction pipe to suck out the lubricating oil in the sealing seat cavity. Prepare a workbench and disassembly tools for placing the pump parts. Do not use them indiscriminately to avoid damaging the pump parts.

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Dismantling the split coupling: first unscrew the fixed hexagon socket head cap screw of the coupling, then gently pull half of the coupling off the shaft slowly, being careful not to drop it, then unscrew the pump with a Torx wrench Tighten the bolt and stopper on the shaft, let the impeller slowly sink to the pump body, then remove the other half of the coupling and take off the pump shaft retaining ring.

To remove the mechanical seal: Grab the seal spring and lift it up along the pump shaft to remove it.

Disassemble and clean the bearing seat: first move the bearing seat lightly, then use the dismantling bolt to lift the bearing seat, and lift it up along the pump shaft to remove, then use jet fuel to clean the bearing and seat, dry and apply a little before installation No. 20 mechanical oil is used for lubrication and protection.

Dismantling the seal seat: unscrew the seal seat compression nut, gently remove the seal seat and clean it.

Mechanical seal assembly: Apply a layer of clean No. 20 lubricating oil on the mirror surfaces of the moving and static rings, and apply lubricating oil to the guide bearing seat. First, lightly position the static ring into the guide bearing seat, and then smear the pump shaft. Lubricating oil, lightly install the moving ring part on the pump shaft, push the sealing ring lightly by hand, and it should be able to expand and contract freely. Note that the anti-rotation parts of the dynamic and static ring parts need to be assembled in place.

Install the coupling: install the retaining ring on the motor shaft head, install half of the coupling, then install the stopper on the pump shaft end and the coupling groove and tighten the bolt with a Torx wrench; then install the other half of the coupling to tighten Upper socket head cap screws. Correct inspection requirements for the installation of the coupling: the upper and lower clearances of the split coupling need to be uniform, and the coupling should be turned by hand several times to check the flexibility of rotation.

Install the seal seat: first install the seal seat into the rubber oil seal, then put the seal seat into the pump cover and press it on the bearing seat, tighten the nuts, and ensure that all the mounting screws are fastened. When the mounting screw is used as the drive between the seal and the shaft, the shaft should be countersunk to reinforce the connection, and the gland bolts should be tightened smoothly and the gland should not be under elastic force. Use an equally spaced gland with more than 4 screws where possible. When tightening the gland bolts, use a feeler gauge to check the gap between the shaft and the gland. This is especially important when the seal cavity is not guided to the gland. Because the gland must be centered.