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Stuffing Box Sealing

It should be noted that this system requires a higher quantity of flush
water and most of it will enter the pumpage.
Although the materials from which packing is manufactured have
changed considerably since it was first introduced during the nineteenth
century, it still provides the same advantages and drawbacks.

Advantages It is relatively inexpensive to purchase.
It is rarely the cause of catastrophic pump failure.
It can be adjusted or replaced without pump
disassembly.

Most maintenance personnel are accustomed to its
USe.
Disadvantages It lowers pump efficiency.

Packing and sleeve require regular replacement.
The packing requires regular adjustment.
Adjustment requires the touch of an experienced
millwright.

It is required to permit constant leakage.
It often requires considerable volumes of flush water.
Although constant leakage is required to ensure lubrication between
the packing and sleeve, it is now only acceptable if the pumps are
handling clean water.

6.3 Mechanical seals

In view of society's increasing awareness of environmental concerns, the
leakage required by packing is becoming unacceptable with the more
aggressive liquids now common in our industrial processes.
Consequently, packing is being replaced by mechanical seals in a
growing number of applications.
A mechanical seal operates by having two flat faces running against each
other. The rotating face is secured to the pump shaft while the
stationary face is held in the gland. As one face is moving while the
other is held stationary, his type of seal is referred to as a 'Dynamic'
seal.
In a basic seal, there arc four possible leak paths which must be secured.
1. Between the two Seal Faces.
2. Between the Rotating Face and the Shaft.

89 m