Type Selection Method

Mechanical seals are different from non-standard mechanical seals according to working conditions and medium properties, including high temperature and low temperature resistant mechanical seals, high pressure and corrosion resistant mechanical seals, granular medium resistant mechanical seals and light hydrocarbon medium mechanical seals which are easy to vaporize, etc. Mechanical seals for different kettles should be selected according to different uses. Mechanical seals for moulding and materials.

The main parameters of type selection are: pressure of sealing chamber (MPA), temperature of fluid (C), working speed (M/S), characteristics of fluid and useful space of device seal, etc.

The basic principles of type selection are as follows:

1: According to the pressure of the sealing chamber, it is concluded that the sealing structure should be balanced or non-balanced, single-end or double-end.

2: According to the working speed, the rotary or stop type, hydrodynamic pressure type or non-touch type are selected.

3: According to the temperature and fluid properties, the conflict pair and auxiliary seal data are determined, and the smooth, scouring, heat preservation, cooling and other mechanical seal cycle protection systems are selected accurately.

4: According to the useful space of the device seal, it is determined that multi-spring or single-spring or waveform-spring, inner-spring or outer-spring are selected.

II. Devices and Operation Requirements for Mechanical Seals

1: Requirement of Mechanical Seal for Machine Accuracy (Take Mechanical Seal for Pump as an Example)

(1) The maximum radial runout of the shaft (or sleeve) in the mechanical seal part of the device shall not exceed 0:04-0:06MM.

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

(3) The maximum run-out of the positioning end face of the shaft (or sleeve) combined with the sealing chamber and the sealing end cap should not exceed 0:04-0:06MM.

2: Recognition of Seals

(1) Recognize whether the seal of the device is the same as the type of request.

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

(3) Mechanical seals driven by parallel ring tension springs are selected. The tension springs can be divided into left and right rotation. They must be selected according to the rotation history of the rotating shaft.

3:Device

Installation method varies with mechanical seal type and machine type, but its installation method is almost the same. Installation process and precautions are as follows:

(1) Determination of device scale

Installation shall be in accordance with the instructions or samples for the use of commodities to ensure the device size of mechanical seals.

(2) Before loading, the shaft (sleeve) and pressure cap should be burr-free and the bearing is in good condition. Seals, shafts, sealing chambers and pressure caps should be clean and clean. In order to reduce the conflict resistance, the mechanical seal part of the shaft device should be coated with a thin layer of oil for smoothing. Considering the compatibility of rubber O-rings, soap water can be applied if oil is not suitable. Floating static ring without anti-reselling structure, not suitable for oil, should be dry loaded into the cap.

(3) Firstly, the static ring and the cap are mounted on the axle together. Be careful not to collide with the axle, and then the moving ring assembly is mounted. The fastening screw of the tension spring seat or transmission seat should be tightened evenly in several times.

Before fixing the cover, the compensating ring is compressed axially by hand. After loosening, the compensating ring can automatically rebound to the image of no sticking, and then the cover bolt is locked evenly.

4: Application

(1) When the temperature of the transport medium is too high, too low, or is rich in impurity particles, flammable, explosive and toxic, it is necessary to take corresponding measures such as blocking, scouring, cooling and filtering.

(2) Before operation, use the handwheel, pay attention to whether the torque is too large, whether there are scratches and abnormal sounds.

(3) Pay attention to the direction of rotation, whether the coupling is aligned, whether the lubricating oil addition at the bearing position is appropriate, and whether the piping is accurate.

(4) Before operation, the medium and cooling water valves are first opened to check whether the gas in the sealing chamber is exhausted completely, so as to avoid leakage caused by static pressure, and then the machine is turned on and running.

(5) Whether the operation is normal and stable after driving, whether there are abnormal torques caused by shaft rolling, as well as abnormal sounds and overheating appearances.