Theory Operation

Refrigerated Dryers remove moisture by cooling the compressed air to a temperature of 2°C to 4°C. The GEM DRYERS include two separate circuits, a compressed air circuit and refrigeration circuit.

Compressed Air Circuit

The Compressed air drying circuit uses an air-to-air exchanger, which acts as a pre-cooler/re heater, and an air- to-refrigerant heat exchanger. Both heat exchangers use the latest in tubing technology; a shell and tube design that gives superior heat transfer. The tubing in both heat exchangers is copper to increase heat transfer, increase service life and reduce corrosion.
Warm, saturated air first enters the air-to-air heat exchanger (A) where it is pre-cooled. By pre-cooling the incoming air, energy saved through reduction of the heat load imposed on the refrigerant compressor and condenser. Saturated air then enters the air to refrigerant heat exchanger (B) further reducing the air temperature to specified dew point of 2°C or 10°C. Water is condensed as the air is cooled to the specified dew point.
The cold air then flows through a moisture separator (C) where the condensed water is removed and discharged from the dryer through the automatic drain (K).
The chilled air then re-enters the air-to-air heat exchanger where it is reheated. Reheating of air does not affect the dew point. The cooled air flows through the air-to-air heat exchanger in a direction opposite.

Tips For Successful Operation:

Do not exceed Dryers rated design flow and inlet temperature (40°C) to avoid poor dew point.
Keep the Dryer in clean and ventilated room. There should not be any dust and other contaminants which may block the condenser unit (Air Cooled models). The cooling water should be properly treated and should be at ambient temperatures (water cooled models).
Do not adjust / tamper any of the components in the Dryer, these are factory set and should be adjusted only by the authorised service persons.
Do provide a good after cooler. This will bring down the inlet air temperature of compressed air.
Do provide a stabilizer if your voltage fluctuates too much.

Installation

GEM Air Dryer is a self contained unit with all accessories provided on the skid. No special foundation is required. A closed room protected from rain, moisture and dust is preferable. The compressor room will be an ideal location.
The air to the Dryer should be sufficiently cool (25 Deg.C to 40 Deg.C) to get the best performance, so an after cooler is necessary. Check if your compressor has one in good working condition.

Dryer should be mounted on a level surface and free from any transmitted vibration. The surrounding temperature should not be abnormally high (above 40 Deg. C).
The Dryer should be properly located so that sufficient cool fresh air enters the condenser. There should be no dirt or dust in cooling air. (In case of air cooled model).
In water cooled units connect the condenser to the factory cooling tower. Provide a control valve on water inlet to control the flow.
Provide proper rigid piping for inlet and outlet. Provide a bypass valve arrangement to isolate Dryer during maintenance.
Connect the outlet of the condensate drain to suitable location away from the Dryer unit.

Start up Procedure

Open the inlet valve to the Dryer and cooling water line
Open the refrigerant holding receiver valves.
Switch on the main Switch and compressor switch.
Check the refrigerant pressure.
If your unit is provided with a electronic auto drain check its functioning by operating manually.

Preventive Maintenance

Gem Dryers are built for trouble free operation round the clock service. But it requires some small care which keeps the equipment in best condition to give better performance and to last longer.

Daily

Check Oil level in the Compressor crank case and refill if necessary (for open type only).
Clean the condenser from inside. (Air cooled Model)
Check water supply to the condenser (Water cooled Model)
Check Auto drain functioning.
Check refrigerant pressure.

Monthly

Check all joints for leakages.
Check dew point temperature and running hours of compressor.
Clean the condenser from outside with soap water to avoid dust coating.
Clean/Service auto drain valves.
Check Safety trip accessories.

Yearly

Check refrigerant charge; Recharge if necessary.
Descale the condenser. (Water cooled).

Trouble Shooting

Nature of Problem	Reason for the Defect
1. Compressor Do not Start.	Power supply not correct / Fuse blown.
	Overload relay tripped
	Safety accessories tripped.
2. Compressor Trips	Check Overload protector
	Check dew point settings
	Start capacitor failure (Single phase Models)
	Compressor failure/seized.
3. System Goes OFF; &l Fault light Indication.(For Models above 200 cfm only)	Overload protector tripped
	HP / LP safety switch tripped
	Compressor Oil pressure switch tripped.
4. Poor Dewpoint	Excess flow of air
	Inlet air temperature high
	Refrigerant charge low
	Universal Filter / Expansion valve Filter blocked Poor condensation Atmospheric temperature / ventilation not sufficient.(Air Cooled) Cooling water not sufficient (Water Cooled).

NB: Please mention your dryer model no and serial no without fail while ordering for spares. All the above spares to be replaced only on failure of the same.

Recommended Spares For Preventive Maintenance Of Gem Dryer

Description of Spares	Quantity
1. Temperature Indicator....	1
2. Thermostat Switch / Sensor….	1
3. Discharge Pressure gauge….	1
4. Suction pressure gauge....	1
5. HP / LP Pressure switch......	1
6. Silica Gel .....	2 Kgs
7. Freon Gas R12/R22
8. Gas cylinder...........	6 Kgs
9. Auto drain Valve Seal kit…	1 Set
10. Auto drain Timer.......	1 No
11. Solenoid valve 'NC' type….	1 No
12. Main Contactor….	1 No
13. Overload relay….	1 No
14. Ref. Compressor….	1 No
15. Compressor Electrical Accessories….	1 Set
16. Compressor Oil (For open type model)….	5 liters
17. Evaporator Gasket…	1 Set

About Us

Gem Equipments entered the engineering and fabrication industry in 1984. We specialise in design, engineering and fabrication of Cooling Towers, Compressed Air Dryers, Industrial Chillers and Compressed Air Treatment Accessories.

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