These devices are used to separate in the most efficient manner the very fine drops carried away by a gas or steam, either at a boiling stage, vacuum evaporation or bubbling of a liquid. In fact there are two phenomena, one mechanical and one physical, but no filtration at all since the size of the held drops has no realtion with the infinitely greater size of the pore or open ***ce. The head loss or gas passage resistance is practically imperceptible, however demisting can reach up to 99% efficiency. A demister reaches the highest efficiency when the speed of a gas or steam ranges between certain limits:
U Once the highest speed has been reached it is possible to set both the best and the lowest speeds of the demister, setting respectively to 75% and 30% of the Vm to get above mentioned speeds.
Low speeds rather than high speeds affect the efficiency of a demister so, if necessary, it is always advisable to operate at high speeds.
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