Flowserve FRBHJC - Manual (Page 27)

FRBHJC USER INSTRUCTIONS ENGLISH 71569179 11-04
Page 27 of 42
®
5.9.2 Viscosity
For a given flow rate the total head reduces with
increased viscosity and increases with reduced
viscosity. Also for a given flow rate the power
absorbed increases with increased viscosity, and
reduces with reduced viscosity. It is important that
checks are made with your nearest Flowserve office if
changes in viscosity are planned.
5.9.3 Pump speed
Changing pump speed effects flow, total head, power
absorbed, NPSH
R
, noise and vibration. Flow varies in
direct proportion to pump speed, head varies as speed
ratio squared and power varies as speed ratio cubed.
The new duty, however, will also be dependent on the
system curve. If increasing the speed, it is important
therefore to ensure the maximum pump working
pressure is not exceeded, the driver is not overloaded,
NPSH
A
> NPSH
R
, and that noise and vibration are
within local requirements and regulations.
5.9.4 Net positive suction head (NPSH
A
)
NPSH available (NPSH
A
) is a measure of the head
available in the pumped liquid, above its vapour
pressure, at the pump suction branch.
NPSH required (NPSH
R
) is a measure of the head
required in the pumped liquid, above its vapour
pressure, to prevent the pump from cavitating. It is
important that NPSH
A > NPSH
R
. The margin between
NPSH
A
> NPSH
R
should be as large as possible.
If any change in NPSH
A
is proposed, ensure these
margins are not significantly eroded. Refer to the pump
performance curve to determine exact requirements
particularly if flow has changed. If in doubt please
consult your nearest Flowserve office for advice and
details of the minimum allowable margin for your
application.
5.9.5 Pumped flow
Flow must not fall outside the minimum and maximum
continuous safe flow shown on the pump performance
curve and/or data sheet.
6 MAINTENANCE
6.1 General
It is the plant operator's responsibility to ensure
that all maintenance, inspection and assembly work is
carried out by authorized and qualified personnel who
have adequately familiarized themselves with the
subject matter by studying this manual in detail. (See
also section 1.6.2.)
Any work on the machine must be performed when it is
at a standstill. It is imperative that the procedure for
shutting down the machine is followed, as described in
section 5.8.
On completion of work all guards and safety devices
must be re-installed and made operative again.
Before restarting the machine, the relevant instructions
listed in section 5, Commissioning, start up, operation
and shut down must be observed.
Oil and grease leaks may make the ground
slippery. Machine maintenance must always begin
and finish by cleaning the ground and the exterior
of the machine.
If platforms, stairs and guard rails are required for
maintenance, they must be placed for easy access to
areas where maintenance and inspection are to be
carried out. The positioning of these accessories must
not limit access or hinder the lifting of the part to be
serviced.
When air or compressed inert gas is used in the
maintenance process, the operator and anyone in the
vicinity must be careful and have the appropriate
protection.
Do not spray air or compressed inert gas on skin.
Do not direct an air or gas jet towards other people.
Never use air or compressed inert gas to clean clothes.
Before working on the pump, take measures to prevent
an uncontrolled start. Put a warning board on the
starting device with the words:
"Machine under repair: do not start".
With electric drive equipment, lock the main switch
open and withdraw any fuses. Put a warning board on
the fuse box or main switch with the words:
"Machine under repair: do not connect".
Never clean equipment with inflammable solvents or
carbon tetrachloride. Protect yourself against toxic
fumes when using cleaning agents.
6.2 Maintenance schedule
It is recommended that a maintenance plan and
schedule is adopted, in line with these User
Instructions, to include the following:
a) Any auxiliary systems installed must be monitored,
if necessary, to ensure they function correctly.