Installation and use of mechanical seals for vacuum pumps and diaphragm pumps1

1. The requirements of the mechanical seal on the machine precision: (take the mechanical seal of the vacuum pump as an example)

(1) The maximum radial runout tolerance of the shaft (or shaft sleeve) where the mechanical seal is installed shall not exceed 0.04-0.06mm.

(2) The axial movement of the rotor does not exceed 0.3mm.

(3) The runout tolerance of the positioning end of the sealing cavity combined with the sealing end cover facing the surface of the shaft (or shaft sleeve) should not exceed 0.04~0.06mm at most.

2. Confirmation of seals:

(1) Confirm whether the installed seal is the same as the required model.

(2) Before installation, carefully check with the general assembly drawing to see if the number of parts is complete.

(3) The mechanical seals are driven by parallel springs. The springs are divided into left and right rotations, which must be selected according to the rotation direction of the rotating shaft.

3. Installation method of seals:

The installation method varies with the type of mechanical seal and the type of machine, but the installation essentials are almost the same. The installation steps and precautions are as follows:

(1) Determination of installation size: During installation, the installation size of the mechanical seal should be guaranteed according to the product instruction manual or sample.

(2) Before loading, the shaft (sleeve) and gland should be free of burrs, and the bearing should be in good condition; the seals, shaft, sealing cavity and gland should be cleaned. In order to reduce frictional resistance, the part where the mechanical seal is installed on the shaft should be coated with a thin layer of oil for lubrication. Considering the compatibility of rubber O-rings, if oil is not suitable, soapy water can be applied. The structure of floating static ring without anti-rotation pin should not be oiled, and should be installed in the gland dry.

(3) Install the static ring together with the gland on the shaft first, being careful not to collide with the shaft, and then install the moving ring assembly. The set screw of the spring seat or transmission seat should be evenly tightened several times.

Before the gland is not fixed, push the compensation ring by hand for axial compression. After loosening, the compensation ring can automatically spring back without jamming, and then lock the gland bolts evenly.