UB USER INSTRUCTIONS ENGLISH 71569247 07-04
Page 20 of 32
®
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. It should include the following:
a) Any auxiliary systems installed must be monitored,
if necessary, to ensure they function correctly.
b) Gland packings must be adjusted correctly to
give visible leakage and concentric alignment of
the gland follower to prevent excessive
temperature of the packing or follower.
c) Check for any leaks from gaskets and seals. The
correct functioning of the shaft seal must be
checked regularly.
d) Check bearing lubricant level, and if the hours
run show a lubricant change is required.
e) Check that the duty condition is in the safe
operating range for the pump.
f) Check vibration, noise level and surface
temperature at the bearings to confirm
satisfactory operation.
g) Check dirt and dust is removed from areas around
close clearances, bearing housings and motors.
h) Check coupling alignment and re-align if necessary.
