Outlet Pipe; Shaft Seals - Grundfos KP Notice D'installation Et De Fonctionnement

4.5.2 Variable frequency drive operation
• In principle, all three-phase motors can be connected to a
variable frequency drive.
• However, variable frequency drive operation will often expose
the motor insulation system to a heavier load and cause the
motor to be more noisy than usual due to eddy currents
caused by voltage peaks.
If in doubt whether the motor supplied can handle
variable frequency drive operation, contact the motor
supplier.
• In addition, large motors driven via a variable frequency drive
will be loaded by bearing currents.
• When the pump is operated via a variable frequency drive,
check the following operating conditions:
Operating
Action
conditions
2-, 4- and 6-pole Check to make sure that one of the motor
motors of 45 hp bearings is electrically isolated. If not,
and up contact Grundfos.
Noise-critical Fit a dU/dt filter between the motor and the
applications variable frequency drive, it reduces the
voltage peaks and thus the noise.
Particularly noise- Fit a sinusoidal filter.
critical applications
Cable length Fit a cable that meets the specifications
laid down by the variable frequency drive
supplier. The length of the cable between
motor and variable frequency drive affects
the motor load.
Supply voltage up Check that the motor is suitable for
to 500 V variable frequency drive operation.
Supply voltage • Fit a dU/dt filter, it reduces the voltage
between 500 V and peaks and thus the noise,
690 V or
• check that the motor has reinforced
insulation.
Supply voltage of • Fit a dU/dt filter, it reduces the voltage
690 V and upwards peaks and thus the noise,
and
• check that the motor has reinforced
insulation.

4.6 Outlet pipe

• A short outlet pipe can be the same diameter as the pump
outlet port. A long pipe must be one or two sizes larger than
the outlet port, depending on the length.
• It is best to use long horizontal outlet pipes.
• Install a gate valve near the outlet port to be able to isolate the
pump during shutdown and maintenance, and to facilitate
pump removal.
• Any high points in the outlet pipe may entrap air or gas and
thus impede pump operation.
• If water hammer occurs, that is if check valves are used, close
the outlet gate valve before pump shutdown.
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4.7 Shaft seals

The KP pumps are available with stuffing boxes with packing
rings or mechanical shaft seals.
4.7.1 Stuffing boxes (KP)
The stuffing boxes are normally packed before shipment.
If the pump is installed within 60 days, the packing material will be
in good condition for operation with a sufficient supply of
lubricating liquid.
If the pump is stored for more than 60 days, it may be necessary
to repack the stuffing boxes.
The stuffing box must be supplied at all times with a source of
clean, clear liquid to flush and lubricate the packing rings.
4.7.2 Packing gland adjustment (KP)
Make sure that the flushing fluid lines are connected and their
valves are open.
With the pump running, adjust the packing gland to permit 40 or
60 drops per minute for shaft lubrication.
Tighten the packing gland evenly to provide uniform compression
on the packing material.
Do not operate packing dry, and do not over-tighten the packing
gland to eliminate leaking as this will cause the shaft sleeve to be
damaged.
After initial startup, additional packing and adjustment may be
required.
4.7.3 Mechanical seals
Mechanical shaft seals require no maintenance or adjustment.
KP, KPV, KPVS pumps equipped with mechanical shaft seals are
matched to the operating conditions for which the pump was sold.
Observe the following precautions to avoid shaft seal damage
and to obtain maximum shaft seal life:
Do not run the pump dry or against a closed valve.
Dry operation will cause shaft seal failure within
minutes.
Do not exceed temperature or pressure limitations
for the mechanical seal used.
Purge all air from the seal chambers and recirculation lines prior
to operating the pump.
• Clean and purge the inlet pipe in new installations before
installing and operating the pump. Pipe scale, welding slag
and other abrasives can cause rapid shaft seal failure.
• A mechanical shaft seal does not leak at all during normal
operation, therefore if any appreciable leakage occurs, the
seal must be removed, inspected and if necessary replaced.
We recommend keeping a stock of spare parts to reduce
equipment down time.