> sea water pressure low because of Ships draft, choked filters, fault in pump etc.
> Level of brine is too high
> Faulty Ejector nozzle/ nozzle choked
> Incorrect feed
> scale formation in evaporator or condenser
> shell temperature is too high
> condenser cooling water flow is reduced
> Condenser cooling water temp. too high
> Incorrect assembly of plates
> improper vacuum dueto the leakage in plants like from pressure gauge, vent, distillate pump seal etc.
Vacuum is not maintaining
> Air leaks into the evaporator shell in large quantities and the air ejector cannot cope.
> The cooling water flow through the condenser is reduced or the cooling water temperature is high. This causes saturation temperature and hence saturation pressure within the condenser to rise.
> Malfunctioning of the air ejector.
> The flow rate of the heating medium increased and excess water vapour produced. Since this excess vapours cannot be condensed, shell pressure increases or vacuum falls.
Increase in Salinity of Freshwater
> Brine level inside the shell too high.
> Leaking condenser tubes or plates.
> Operation of evaporator near shore with contaminated feed water.
> Shell temperature and pressure are too low.
> Increased solubility of CO2 generated from the salt water due to reduced seawater temperature. This dissolved CO2 makes water acidic and conductivity of water increases. Hence salinometer shows increased salinity, which is a measure of conductivity and not the presence of salt.