Goulds-pumps 3409 - IOM User Manual download pdf (Page 24)

24 3409 IOM 11/04

STUFFING BOX LUBRICATION

Contaminants in the pumped liquid must not enter the

stuffing box. These contaminants may cause severe

abrasion or corrosion of the shaft, or shaft sleeve, and rapid

packing or mechanical seal deterioration; they can even

plug the stuffing box flushing and lubrication system. The

stuffing box must be supplied at all times with a source of

clean, clear liquid to flush and lubricate the packing or seal.

The most important consideration is to establish the

optimum flushing pressure that will keep contaminants

from the stuffing box cavity. If this pressure is too low,

fluid being pumped may enter the stuffing box. If the

pressure is too high, excessive packing or seal wear may

result; and extreme heat may develop in the shaft causing

higher bearing temperatures. The most desirable condition,

therefore, is to use a seal water pressure 15-20 psig above

the maximum stuffing box pressure.

If the pump system pressure conditions vary, packing

adjustment becomes difficult. Consideration should be

given to using a mechanical seal. (See Mechanical Seals.)

PACKING

Packed stuffing boxes are not allowed in an ATEX

classified environment.

Standard pumps are normally shipped with the packing set

loose (not installed). If the pump is installed within 60

days after shipment, the packing will be in good condition

with a sufficient supply of lubrication. If the pump is stored

for a longer period, it may be necessary to replace the

factory supplied packing set. In all cases, however, inspect

the packing before it is installed and the pump started.

NOTE: Packing adjustment is covered in the

Maintenance section of this manual.

On some applications, it is possible to use internal liquid

lubrication (pumped liquid) to lubricate packing. Only

when all of the conditions prevail, can this be done:

1. Liquid is clean, free from sediment and chemical

precipitation and is compatible with seal materials.

2. Temperature is above 32° F and below 160° F.

3. Suction pressure is below 75 psig.

4. Lubrication (pumped liquid) has lubricating qualities.

5. Liquid is non-toxic and non-volatile.

When the liquid being pumped contains solids or is

otherwise not compatible with packing materials, an

outside supply of seal liquid should be furnished. In

general, external-injection liquid (from an outside source)

is required when any of the above conditions cannot be

met.

The standard stuffing box consists of six (6) rings of

packing and a split type gland. A shaft sleeve which

extends through the box and under the gland is provided to

protect the shaft.

A tapped hole is supplied in the stuffing box directly over

the seal cage to introduce a clean, clear sealing medium.

The stuffing box must, at all times, be supplied with sealing

liquid at a high enough pressure to keep the box free from

foreign matter, which would quickly destroy the packing

and score the shaft sleeve.

Only a sufficient volume of sealing liquid to create a

definite direction of flow from the stuffing box inward to

the pump casing is required, but the pressure is important.

Apply seal water at a rate of approximately .25 GPM at a

pressure approximately 15 to 20 psig above the suction

pressure. (Approximately one [1] drop per second.)

One recommended method to minimize error in regulating

flushing water is a “Controlled Pressure System.” (Fig. 13)

Most important is the pressure reducing valve adjusted to a

value slightly exceeding the maximum stuffing box

operating pressure (assuming it is reasonably constant). A

flow indicating device will serve to indicate a failing of the

bottom packing rings allowing leakage in the pump.

External sealing liquid should be adjusted to the point

where the packing runs only slightly warm, with a very

slow drip from the stuffing box. Excess pressure from an

external source can be very destructive to packing. More

pressure is required, however, for abrasive slurries than for

clear liquids. Examination of the leakage will indicate

whether to increase or decrease external pressure. If slurry

is present in the leakage, increase the pressure until only

clear liquid drips from the box. If the drippage is corrosive

or harmful to personnel, it should be collected and piped

away.

Fig. 13

Pump

Casing

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 67 68

Comments to this Manuals

No comments

Goulds-pumps 3409 - IOM User Manual Page 24

Comments to this Manuals

Related products and manuals for Pumps Goulds-pumps 3409 - IOM