ITT GOULDS PUMPS 3316, Инструкции по установке, эксплуатации и обслуживанию

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5
Operation
5.1
Operation
Stuffing box
1. Stuffing Boxes with Packing Rings - Less Quenching Gland:
Periodically inspect stuffing box to see that there is sufficient leakage to lubricate the pack ing
and maintain a cool box. Never draw up packing so that the stuffing box heats, as this will cause
damage to both packing and sleeve. Always draw up gland nuts evenly and when pump is run-
ning.
After pump has been in operation for some time and the packing has been completely run in, at
least 40 to 60 drops per minute of the liquid should be allowed to trickle from the stuffing box at
all times for cooling and lubricating the packing and shaft sleeve.
2. Stuffing Boxes With Packing Rings - With Quenching Gland:
The same precautions as described above apply. However, the amount of leakage through the
packing cannot be so readily ascertained, due to the quenching liquid. In most cases, the valve
on the quenching liquid supply line can be shut off for a short period and the amount of leakage
determined as in 1. In no instance should the gland be drawn up tight.
3. Stuffing Boxes with Mechanical Seal:
This type of box requires no attention other than to make sure that the circulating lines do not
become clogged.
5.2 Operating at reduced capacities
Do not operate a centrifugal pump at greatly reduced capacities or with discharge gate valve closed, be-
cause the energy required to drive the pump is converted into heat. If this condition exists over a long
period, the temperature of the liquid in the pump may increase until the boiling point is reached. If this
occurs, the rotating parts are exposed to vapor with no lubrication and they may score or even seize to
the stationary parts; and furthermore, if running clearances have enlarged due to wear, seizure may not
take place. Continued operation under these conditions may create an explosive hazard due to the con-
fined vapor under high pressure and temperature.
To guard against possible damage, protective devices are available, such as:
1. Liquid temperature relay or thermostat which will shut-off the unit if the liquid temperature in the
pump exceeds a predetermined maximum. This device guards against possible damage due to
running the pump against a closed valve.
2. Constant open by-pass orifice between the pump discharge and any check or regulating valve in
the discharge line. The liquid through the orifice is returned to the suction source. The amount of
liquid by-passed is a function of input horsepower and the allowable temperature rise. This de-
vice also is insurance against damage due to running the pump against a closed discharge valve
or very low flow conditions.
3. Bearing temperature relay which will shut the unit down of the bearing temperature exceeds a
predetermined maximum.
4. Low suction pressure control which will shut off the unit should the suction pressure drop below a
pre-established minimum.
5
Operation
3316 Installation, Operation and Maintenance Instructions 27