Description

MECHANICAL SEAL이 유체의 아력에 따라 영향을 받게 되는데 통상 저압용은 UNBALANCE TYPE, 고압용은 BALANCETYPE으로 구분하여 사용한다.유체가 고압일 때 SEAL FACE에 면압이 증가하여 어느 한계치를 초과하면 윤활막이 없어지면서 DRY RUNNING하게 되므로 발열과 마모가 증대되어 LEAK와 수명저하의 원인이 된다.

Surface roughness

Microfinished sliding faces made of various materials display the followingaverage, arithmetic mean roughness values(Ra):

Tungsten carbide,nickel-bonded 0.01㎛ Carbon graphite 0.10㎛Silicon carbide(SiC) 0.04㎛ Aluminium oxide 0.15㎛Special cast Cr-steel 0.15㎛ C-SiC-Si/C-SiC 0.15㎛

The lower the roughness value, the higher the percentage bearing areaand hence the higher load capacity of a mechanical seal.

Turbulence losses Pv

The turbulence-related consumption of power is not significant until thecircumferential speed reaches 30 m/s. It must be given due considerationparticularly with special seals.

Power consumption

The total power consumption of a mechanical seal is calculated from

The power consumed by the sliding faces.

The power consumption due to turbulence created by the rotating parts.

Sliding velocity Vg

The sliding velocity is usually quoted in relation to the mean sliding face diameter.

Cooling water requirements

When estimating the amount of cooling water required by heat exchangers  it can be assumed that the temperature of the cooling water will increase by 5 K between the inlet and the outlet. This meansthat 1 I/min of cooling water dissipates 350 W.