Manufacturers of mechanical seals: What is the life of mechanical seals? Mechanical seals

Manufacturers of mechanical seals: what are the daily life of mechanical seals

2020-06-13 13:57

The mechanical seal is one of the most sophisticated mechanical basic components. It is a key component of various pumps and reaction pumps. Its sealing performance and service life depend on many factors, such as type selection, machine precision, correct installation and use, etc.

1. Selection method

According to the working conditions and medium characteristics of textile printing and dyeing mechanical seals, mechanical seals include high-temperature, low-temperature mechanical seals, high-pressure, corrosion-resistant mechanical seals, and mechanical seals with different structures and materials should be selected according to different purposes, such as granular medium mechanical seals and volatile light Hydrocarbon medium mechanical seal.

The selection of main parameters are: sealing chamber pressure (MPa), fluid temperature (°C), operating speed (m/s), characteristics of the fluid cylinder mechanical seal and effective sealing of the installation space.

The basic principles of selection are as follows:

1. According to the pressure of different sealing chambers, determine whether the sealing system structure design adopts this balanced type or unbalanced type, single end face or double end face, etc.

Depending on the working speed, 2 decide to use rotary or static, hydrodynamic or non-contact.

image 3. According to the temperature and fluid properties, the friction pair and auxiliary sealing material are determined, and the mechanical seal cycle protection system such as lubrication, flushing, heat preservation, and cooling is correctly selected.

Effective sealing of installation spaces is determined by the use of multiple springs or a single spring or wave spring, built-in or externally mounted.

2. Technical requirements for installation and use of mechanical seals

1. Accuracy requirements for mechanical seals (for pump mechanical seals as an example)

(1) The runout tolerance in the radial direction of the shaft (or shaft sleeve) where the construction machinery is installed to seal the structural part cannot exceed 0.04-0.06mm at most.

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

(3) The maximum run-out tolerance between the positioning end face of the sealing chamber and the surface of the sealing end cover and the shaft (or sleeve) is 0.04-0.06 mm.

2. Confirmation of seals

(1) Whether to confirm that the installed model is consistent with the required seal.

(2) Before installation, carefully compare with the general assembly drawing, check the number of parts and whether they are complete.

(3) The mechanical seal ring and the spring motor, which has a spring around the point, have been subject to the selected rotation axis.

3. Installation

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

(1) Determine the installation size

When installing, ensure the installation dimensions of the mechanical seal according to the product manual or samples.

(2) Before installation, the shaft (sleeve), the gland without burrs, and the bearing are in good condition; the seal, the shaft seal chamber, and the cover should be cleaned. In order to reduce friction, an oily coating is installed to lubricate the shaft of the mechanical seal. Considering the compatibility with the rubber O-ring, if the oil should be coated with soapy water. Float type static ring structure, no anti-rotation pin, no oil, should be dry loaded gland.

(3) First install the static ring and the gland together on the shaft, taking care not to collide with the shaft, and then install the moving ring assembly between them. The set screw system of the spring seat or drive seat should be evenly tightened several times.

Before the cover is not fixed, the compensation ring is pushed and compressed in the axial direction by hand, and the compensation can automatically play the ringback tone. After the cable is released, the gland bolts are evenly locked.

4. use

(1) When the temperature of the conveying working medium is relatively high, too low, or contains a large amount of impurity particles, is flammable, explosive, or toxic, some corresponding measures such as blocking, flushing, cooling, and filtering must be taken.

(2) Use the handwheel before operation, and pay attention to whether the torque is too large, whether there is friction and abnormal noise.

(3) Pay attention to the direction of rotation, whether the coupling is in the center, add lubricating oil to the bearing part, and whether the pipeline is correct.

(4) During the operation of the first medium, when the cooling water valve is opened, check whether all the gas discharge chambers are sealed to prevent leakage due to hydrostatic pressure, and then connect them.

(5) Whether the staff can develop and stabilize normally after driving, whether there is abnormal torque caused by shaft rotation, and other abnormal noises and overheating phenomena.