Mechanical seals common sense analysis introduction

First, the selection method

Mechanical seals are different in terms of working conditions and quality of mechanical seals. They are high temperature resistant, low temperature resistant mechanical seals, high pressure resistant, corrosion resistant mechanical seals, particulate medium mechanical seals and light hydrocarbon mediums that are easy to vaporize. For seals, etc., mechanical seals of different planning patterns and materials should be selected according to different uses.

The main parameters of the selection are: sealed chamber pressure (MPA), fluid temperature (°C), working speed (M/S), fluid characteristics, and useful space for equipment sealing.

The basic principles of selection are:

1: According to the pressure of the sealed cavity, it is judged that the seal plan is balanced or unbalanced, single or double end.

2: According to the working speed, it is judged to use rotary or discontinuous, fluid dynamic or non-contact type.

3: According to the temperature and fluid properties, determine the contra-contact and auxiliary sealing materials, and correctly select the mechanical seal circulation protection system such as lubrication, flushing, heat preservation and cooling.

4: According to the useful space of the equipment seal, it is judged to use multiple springs or single springs or wave springs, built-in or exterior.

Second, mechanical seal equipment and application needs

1: The need for mechanical seals for machine accuracy (taking pump mechanical seals as an example)

(1) The mechanical seal of the shaft (or bushing) of the mechanical seal part of the equipment shall not exceed 0:04～0:06MM.

(2) The axial movement of the rotor does not exceed 0:3MM.

(3) The locating tolerance of the positioning end surface of the sealing cavity and the sealing end cover to the surface of the shaft (or bushing) is not more than 0:04~0:06MM.

2: confession of the seal

(1) Whether the seal of the confession equipment is together with the type required.

(2) Before the equipment, carefully check the total assembly drawing, and the number of parts is not complete.

(3) Select the mechanical seal of the coil spring transmission, the spring has the left and right rotation points, and must be selected according to the rotation direction of the shaft.

3: Equipment

The equipment method varies with the type of mechanical seal and the type of machine, but the equipment methods are almost the same. The equipment process and precautions are as follows:

(1) Determination of equipment standards

Equipment should be in accordance with the product's operating instructions or samples to ensure the mechanical seal equipment standards.

(2) Before loading, the shaft (sleeve sleeve) and gland should be free of burrs and the bearing condition is good; the seal, shaft, seal chamber and gland should be cleaned and cleaned. In order to reduce the resistance to resistance, the mechanical seal of the shaft equipment should be thinly coated with a layer of oil for lubrication. Considering the compatibility of the rubber O-ring, if it is not suitable for oil, soapy water can be applied. The floating static ring does not have anti-rotation planning. It should not be oiled. The gland should be installed dry.

(3) First install the static ring and the gland on the shaft, taking care not to touch the shaft, and then load the moving ring assembly. The set screws of the spring seat or the drive seat should be evenly tightened several times.

Before the gland is not fixed, the compensation ring is manually pushed by the axial contraction. After the release, the compensation ring can automatically rebound back to the no-slipping appearance, and then the gland bolt is evenly locked.