The main calculation steps of the mechanical seal empirical design method −

The main calculation steps of the empirical design method of mechanical seal

　2017-08-31　　

The main calculation steps of the empirical design method for mechanical seals:

In addition to selecting an appropriate sealing surface specific pressure, it is also required that the working pv value of the sealing pair is less than the allowable [pv] value. The allowable value is determined under the conditions of the specified service life and allowable wear speed after selecting the sealing materials and matching them appropriately.

The following briefly introduces the main parameter calculation steps and calculation examples of the empirical design method.

Steps for calculating balance of face seal pair (friction pair)

(1) Given known data: internal and external pressures P1 and P2 of the sealing surface, shaft diameter and speed n (r/min).

(2) Choose the sealing type and the material of the sealing pair according to the value to meet the requirements. The average diameter of the sealing surface used in the calculation.

(3) Select the main geometric parameters: the inner and outer diameters of the sealing surface and the balance diameter and the width of the sealing surface b (mm). According to the aspect ratio. Find the load factor of the sealing pair.

(4) Consider the various failure modes that may occur, and determine the area ratio of the seal pair according to the critical area ratio. The expression of the critical area ratio of the mechanical seal is

Where 45 is the correction factor considering various failure modes.

(5) Determine the flow state (laminar flow or turbulent flow), friction state (fluid friction, boundary friction, dry friction or mixed friction) and phase state (liquid phase, gas phase or gas-liquid mixture) of the seal pair:

The flow state is judged based on the Reynolds number of a seal pair only Re. For critical thunder, at that time, the flow pattern was laminar; at that time, the flow pattern was turbulent;

(6) Determine the model of the mechanical seal (parallel plane seal, tapered surface seal, inclined surface seal, wave surface seal or combined seal), while considering the influence of seal surface deformation and temperature, and implement the principle of parallel planes.

(7) Calculate the film pressure coefficient of the sealing pair and the contact specific pressure Pr of the sealing surface.

(8) Check the pv value and contact pressure.

(9) Determine the leakage Q, power consumption N, wear amount W and flushing amount Qs.

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Design calculation of mechanical seal face seal pair (friction pair) 　　 Mechanical seal face seal pair balance calculation example