Selection and Use of Mechanical Seal for Pump

The mechanical seal of the water pump is one of the basic mechanical components with precision and complex structure, and is the key component of various pumps, reaction synthesis kettles, turbo compressors, submersible motors and other equipment. Its sealing performance and service life depend on many factors. Such as selection, machine accuracy, correct installation and use, etc. Mechanical seal installation and use requirements are as follows.

Ⅰ. Accuracy requirements for the mechanical seal

(1) The 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 combination of the sealing cavity and the sealing end cover facing the surface of the shaft (or shaft sleeve) shall not exceed 0.04-0.06MM.

Ⅱ. Confirmation of the mechanical seal for pump

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

(2) Carefully check with the general assembly drawing before installation to ensure that the number of parts is complete.

(3) When a mechanical seal driven by a parallel coil spring is used, the spring can be divided into left and right rotation, which must be selected according to the rotation direction of the rotating shaft.

Ⅲ. Installation of the mechanical seal of water pump

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) 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. Seals, shafts, seal chambers, and glands should all 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. Consider 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, be 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 compensating ring by hand for axial compression. After loosening, the compensating ring can automatically spring back without jamming, and then lock the gland bolts evenly.

Ⅳ. Use of the pump mechanical seal

(1) When the temperature of the conveying medium is too high or too low, or contains impurity particles, flammable, explosive or toxic, corresponding measures such as sealing, flushing, cooling, and filtration should be taken.

(2) Turn the car by hand before running, pay attention to whether the torque is too large, whether there is friction and abnormal sound.

(3) Pay attention to the direction of rotation, whether the coupling is centered, whether the addition of lubricating oil in the bearing part is appropriate, and whether the piping is correct.