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Chemical Pump Mechanical Seal

- Jun 13, 2017 -

Chemical Pump Mechanical seal

Mechanical seals are precision, the structure is more complex mechanical one of the basic components, is a variety of pump equipment, a key component. The sealing performance and service life depend on many factors, such as selection, machine accuracy, proper installation and so on.

First, the selection method

Mechanical seal according to the working conditions and the nature of the medium, there are high temperature, low temperature mechanical seal, high pressure, corrosion resistant mechanical seal, resistant to granular media mechanical seal and easy to vaporize the light hydrocarbon medium mechanical seal, etc. should be based on different The use of different types of structures and materials selected mechanical seal.

The main parameters of the selection are: sealed chamber pressure (MPa), fluid temperature (℃), working speed (m / s), the characteristics of the fluid and the installation of the effective space and so on.

The basic principles of selection are:

1. According to the sealing chamber pressure, to determine the sealing structure using balanced or non-balanced type, single-ended or double-ended and so on.

2. According to the working speed, to determine the use of rotary or static, hydrodynamic or non-contact type.

3. According to the temperature and fluid properties, to determine the friction and auxiliary sealing materials, and the correct choice of lubrication, washing, insulation, cooling and other mechanical seal cycle protection system.

4. According to the installation of the effective space sealed to determine the use of multi-spring or single spring or wave spring, built-in or exterior type.

Second, the mechanical seal installation and use requirements

1. Mechanical seal on the machine accuracy requirements (pump mechanical seal as an example)

(1) The radial runout tolerance of the shaft (or sleeve) of the mechanical seal is not to exceed 0.04 to 0.06 mm.

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

(3) The tolerance of the positioning end to the shaft (or sleeve) surface of the sealing cavity and the sealing end cover is not more than 0.04 to 0.06 mm.

2. Confirmation of seal

(1) Check that the installed seal is in accordance with the required model.

(2) before the installation carefully carefully with the assembly diagram, the number of parts is complete.

(3) the use of circular spring and mechanical seal, the spring left and right of the points, according to the rotation of the shaft to choose.

3. Installation

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

(1) the installation size to determine

Installation, the product should be used instructions or samples to ensure that the mechanical seal installation size.

(2) before loading, shaft (bushings), gland should be no burr, bearing in good condition; seals, shaft, sealed chamber, gland should be cleaned. In order to reduce the friction resistance, the shaft to install the mechanical seal parts to be thin coated with a layer of oil to lubricate, taking into account the rubber O-ring compatibility, if not oil, can be coated with soap and water. Floating static ring without anti-dump structure, not oil, should be dry into the gland.

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

Before the gland is fixed, push the compensation ring for axial compression, release the compensation ring can automatically bounce back without jamming phenomenon, and then tighten the gland bolts.