Suction Under Vacuum

attn : Mr Ang

Under such pumping condition , workout the NPSH available in the system and get pump with
lower NPSH required .It should be lower than NPSH avaialable otherwise the pump is not going to work

For this application ,it is under 10 m bar which is almost 98 % vacuum .
therefore 10 meter x 98% is = 9.8 meter
NPSHA = 10 METER - (scution pressure + vapour pressure ) = 0.2 M
NPSH AVAILABLE IS 0.2 METER
Vacuum ejector is mostly use for this particluar installation(palm oil refinery )
The suction head loss and vapour pressure for above is not taken into consideration
as it is negligible

VIBRATION - CAUSES AND EFFECTS

Vibration can cuased serious effects to pumps as well as other rotating equipment

The causes of vibration can be due to mechanical or hydraulic reasons



Mechanical fault

a) most common is unbalanced impeller .shafts . worn out impeller or even coupling
it is quite common for maintenance personel to change damaged bearings
and put the pump running

b) worn out bearings

c) misalignment of pump and driver

d) Pipe strained

e) mass of pump being too small

f) loose screws on pump mounting or baseplate

g) bent shaft

HYDRAULIC REASON

a) cavitation

b) air in the system ,leak or vortexing

c) too high speed of pump

EFFECTS
a) damages of mechanical seal and the life of mechseal is directly related to the
shaft movement
b) bearings and other pump components