As with any mechanical equipment, condensers should never be located where they are difficult of access, since there will then be less chance of routine main­tenance being carried out. Periodic maintenance of a condenser is limited to attention to the moving parts — fans, motors, belts, pumps — and cleaning of water filters, if fitted.

The overall performance will be monitored from the plant running log (see Chapter 29) and the heat exchange surfaces must be kept clean for maximum efficiency — meaning the lowest head pressure and lowest power.

Air-cooled surfaces may be cleaned by brushing off the accumulation of dust and fluff where the air enters the coil, by the combination of a high-pressure air hose and a vacuum cleaner, or, with the obvious precautions, by a water hose. Foaming detergents are also used.

Advance warning should be had from the plant running log of any build-up of scale on water-cooled surfaces. Scale within the tubes of a straight double­pipe or shell-and-tube condenser can be mechanically removed with suitable wire brushes or high-pressure water lances, once the end covers have been removed. Tubes which cannot be dealt with in this way must be chemically cleaned (see also Chapter 29).

It will be appreciated that, where air and water are present, as in a water cooling tower or evaporative condenser, the apparatus will act as an air washer, removing much of the dust from the air passing through it. Such dirt may be caught in a fine water filter, but is more commonly allowed to settle into the bottom of the tank and must be flushed out once or twice a year, depending on the severity of local contamination. Where heavy contamination is expected, it is good practice to provide a deeper tank than usual, the pump suction com­ing out well clear of the bottom, and tanks 3 m deep are in use. Where plant security is vital, the tank is divided into two parts, which may be cleaned alternately.

Algae and other organisms will tend to grow on wet surfaces, in particu­lar those in daylight. Control of these can be effected by various proprietary chemicals.

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