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Air dryer maintenance do’s and don’ts

163q76.jpgRefrigeration air dryers are very reliable and provided they are correctly selected for the application and installed correctly will give many years of service. Dryers have to be re-rated to operate in South Africa’s high inlet and ambient temperatures and the manufacturer’s design flow rates have to be reduced to keep the thermal load in balance. If operating pressures are lower than 7 bar this also reduces the dryer’s flow capacity. Here are a few rules that should be followed.

Check the condensate drain valve daily. Clean out the strainer, if fitted, every month or as often as necessary. Do not hard pipe the drain valve to the drain system. You can’t see if the drain’s working. Pipe it up with a 30 cm long clear 10 mm diameter sacrificial hose along with push-in fittings. If installed in this manner you can see the drain working and you can unplug it to really see what is happening if you need to.

A dryer with a blocked drain is a water generator, not a device for water removal. The use of a low cost dew point monitor will tell you instantly if the dryer has a blocked drain valve or has a technical problem as it measures the actual water content in the air stream.

Keep the air-cooled freon condenser clean and free from dirt.

Do not use a high pressure power washer, it will bend the fins and cut off the cooling air flow. Reverse blow the condenser with clean, dry 3 bar compressed air as often as necessary to keep it clean. Your site conditions will influence the frequency.

Observe the dew point temperature gauge on the front fascia of the dryer daily, it must read 3°C ±2.

On too many occasions we see dryers in a tripped state, or not even turned on, so it’s vital to train your compressor room operators so that they understand what the normal dryer status indicators are. High pressure freon pressure tripouts are common, especially in summer. The cause of this trip can be:

• Dirty freon air or water cooled condenser.

• Insufficient cooling water flow and/or water cavitations.

• Air volume overload and/or machine undersizing.

• Internal freon compressor thermal overload caused by thermal overload.

• Poor compressor room ventilation.

• Poor positioning of the dryer in a hot air flow generated by compressor coolers.

• Freon HP trips are especially common on full feature air compressors with built-in air dryers. They need special attention and monitoring or dewpoint performance will suffer.

Finally place the dryer under cover or in a well-ventilated compressor room, they are not designed to work when exposed to the elements.

Refrigeration dryers perform a fantastic service and will keep a system clean and dry for years on end, provided you follow these rules. For those that are in the process of designing or reconfiguring a compressor room, why not visit the educational section of the Artic website and download Hints And Tips For Compressor House Design for a few extra ideas.

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