Carrier GY Provozní pokyny stáhnout pdf (Strana 15)

WARNING: Never open or disconnect any switch or circuit

breaker which will cut the supply to the heaters, unless the unit

is to be shut down for lengthy service or repair or for a

seasonal shut down. In all cases the heater must be energised

for at least 24 hours before a compressor is restarted.

Heat exchangers

Evaporator

Protection devices

Freeze-up prevention thermostat

The evaporator is protected against loss of water and freeze-up.

The protection is provided by a thermostat installed in the unit.

Evaporator maintenance

Check that:

• the insulating foam is intact and securely in place.

• the cooler heaters are operating, secure and correctly

positioned.

• the water-side connections are clean and show no sign of

leakage.

Tube-in-tube evaporator (size 020) - cleaning

In some applications, heat exchanger fouling can be very high,

for example when using extremely hard water. The heat

exchanger can be cleaned by circulating a cleaning solution.

Use a tank with a weak acid solution, 5% phosphoric acid or, if

the heat exchanger is frequently cleaned, 5% oxalic acid. Pump

the cleaning solution through the heat exchanger. For optimum

cleaning, the cleaning solution flow rate should be 1.5 times that

of the normal circulation rate, and the direction of flow should

be opposite to that of normal circulation. Afterwards rinse with

large amounts of fresh water, in order to remove all the acid,

before starting up the system again. Clean at regular intervals.

Cleaning in place

Compressors

Checking the oil charge

Check the oil level and add or remove oil as necessary so that

the level is 1/8 to 3/8 up each sight glass with the compressors

running normally.

WARNING: Use only oils which have been approved for use in

refrigeration compressors. Never use oil which has been

exposed to air.

Recommended oil:

30GV

- Polyolester Mobil Oil EAL 68 for semihermetic

compressors

30GY

- Mineral oil, Carrier specification No. PP 33-2

- Suniso 3 GS (Sun Oil Co.)

- Capella WF 32-150

- Clavus G 32 (Shell Oil Co.)

- Gargoyle Artic (Mobil Oil) - original charge

WARNING: All fixing devices and fittings which may have

been removed during servicing must always be replaced upon

completion of the work and before restarting the unit.

Tightening torques to be applied

Description Diameter, mm Torque, Nm

Discharge valve M16 135-140

Cylinder head M12 75-87

Suction and liquid line flange M12 75-87

Suction valve M16 135-140

Compressor motor protection

Circuit breaker

Calibrated, thermo-magnetic, manually reset circuit breakers

protect the compressors against locked rotors and excessive

current draw.

WARNING: Never bypass a circuit breaker or increase its

setting. If a circuit breaker trips, find out why it has done so

and correct the problem before resetting the breaker.

Discharge gas thermostat (DGT)

A sensor in each compressor discharge line opens to shut down

the compressor if the discharge gas temperature exceeds the

preset level.

Cut out 146°C Cut in 113°C

Crankcase heater

Each compressor is fitted with an electric resistance crankcase

heater which prevents any absorption of refrigerant by the

compressor lubricating oil when the compressor is shut down.

Each heater is held in place by a screw clip which must be

secure. Prolonged exposure of the heater to air will result in its

destruction. The heater is energized when the compressor is

switched off.

Multitube evaporators (30GV and 30GY 025-059)

The evaporator can be removed using the following procedure:

• Close the chilled water supply and return valves (if

installed), and disconnect the chilled water supply and

return pipe connections.

• Drain the water from the cooler.

• Remove all temperature sensors from the cooler.

• Fold back the insulation at the refrigerant line

connections.

When the evaporator heads and manifolds are removed, the

outer tube end plates will be visible.

Weak acid

solution

Heat exchanger

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