Liquid Ring Vacuum Pump -Cavitation and Excessive Water

CAVITATION

How to Observe

When the pump cavitate ,pump will prme a rattllig noise and in worst case the pump also vibrates
On visual inspection . you will see pittings on the impeller in between the blades and edge of blades .The finger valve will also get pitted and broken

CAUSES
Usually is cuased by
1) big amont of steam being sucked in from the process
2) too high temperature of sucked gas and/or service liquid
3) too high vacuum at suction
4) service liquid with vapour pressure ( eg mixture of solvent)

Remedy

Anti cavitation valve is a good preventive measure ,but it is not a solution when the
cavitation is serious and continous, other alternative could be looked into
One of which if the Guage reading is showing about 35 m bar and below . see if can operate at lower vacuum

EXCESS OF WATER

You will notice cases of impeller blades bent or broken

Causes
1) Water is not drained when the pump stopped .the pump will start with too much water
in the pump(instal an automatic drained valve )
2) too much pressure or head of service liquid feeding(instal regulating valve for this purpose )

3) too much water or condensable steam being sucked from the process
Typical problem , for pumps used in drying process without good condensor /separator
between the pump and the process

In one soap noodle plant, the condenser is feeded water from the cooling tower
.At the water discharge area ,choked by dirt from the water system and the water
flooded the nozzle at vacuum suction line .Big amount of water is being drawn to the vacuum line