HP 8-UB-1 User Manual download pdf (Page 20)

UB USER INSTRUCTIONS ENGLISH 71569247 07-04

Page 20 of 32

5.9.4 Net positive suction head (NPSH

)

NPSH available (NPSH

) is a measure of the head

available in the pumped liquid, above its vapour

pressure, at the pump suction branch.

NPSH required (NPSH

) 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

> NPSH

. The margin between

NPSH

> NPSH

should be as large as possible.

If any change in NPSH

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.

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