Card 5. Precautions when stopping machinery

If the compressor is to be stopped for a short while only it is sufficient to open the starting switch. In plants which are not fully automatic, the shut-off valves to and from every evaporator should also be closed at the valve station. This prevents the refrigerant from gradually passing from the warmer evaporators and collecting in the coldest one which might cause knocking when the compressor is restarted. f the hand control valves have been used, they should always be closed immediately after the compressor is stopped.

If the refrigeration plant is not to be used for a long time, it is advisable to collect most of the refrigerant in the condenser and receiver. After a lengthy shut-down it may happen that the oil film on the sealing faces of the shaft seal gradually disappears, allowing refrigerant to ooze out.

The shut-down may be effected as follows:

1. Close the liquid valve at outlet from the receiver.

2. Operate the compressor so as to suck the refrigerant out from the evaporators. Interrupt this process when the pressure in the evaporators has dropped to a little above atmospheric. (The pressostat may have to be locked in the engaged position.) If the receiver and condenser can not accept the whole refrigerant charge from the evaporators, sucking must be interrupted as soon as the condenser pressure begins to rise rapidly. The remainder of the refrigerant may be collected in available refrigerant cylinders.

3. Stop the cooling-water pump (pumps).

4. Immediately afterwards switch off the compressor starter.

5. Close the compressor service valves.

6. Stop the fans.

7. If there is reason to fear that the machinery may freeze in winter, the water in the condenser tubes, etc. must be drained off.

oil film - масляная пленка

sealing faces - поверхности уплотнения

the pressostat is in the engaged position - регулятор давления включен

the remainder - остаток

available - имеющийся

Card 6. Operation

1. Fully open the valves at the refrigerant outlet and inlet of the compressor and the condenser. The cover of the stop valves should be tightened up as it was with care not to impair the packing.

2. Fully open the valves at the cooling water inlet and outlet of the condenser.

3. Open the air plug at the top of the condenser front cover and vent all the air from the cooling water circuit.

4. Inspect if there is any leaking point of refrigerant or lubricant. Check the refrigerant leakage with a gas detector, especially on the following points. The flange connection parts at the inlet and the outlet of the compressor, mounting positions of oil pressure regulating valves, expansion valve and pressure switch.

Further, inspect oil leakage as well. If oil leakage is found, the refrigerant must leak as well. Therefore, if any oil leakage is found, retighten it additionally. Do not tighten the connections excessively or one-sided.

5. Inspection of the fan and the fan rotary direction. Rotate the fan several times by hand and check if there is any thing unusual with the bearing. Press the button switch marked "FAN", and confirm the fan rotary direction. If the rotary direction is wrong, reconnect the main wires to rotate the fan correctly. Rotary direction can be changed by exchanging two wires in the three wires. Further, be careful that the fan sometimes blows off dust when it is operated for the first time.

6. Adjust the vanes of the air outlet grille so that the cool air is distributed to the room evenly.

Card 7. Inspection

It is better to inspect the air conditioner daily to protect it against trouble before it occurs than to repair trouble after it had occurred. Perfect maintenance makes it possible to make the air conditioner exhibit its utmost in capacity.

Daily Inspection.

1. Check and record suction pressure and discharge pressure.

2. Check and record voltage and ampere.

3. Check and record cooling water inlet and outlet temperature.

4. Check and record outdoor temperature and room temperature.

5. Check unusual noise and vibration.

Monthly Inspection.

1. Inspect refrigerant leakage with a gas detector.

2. Cleaning of air filter. Remove the air filter and wash it with water. Attach it after it is dried up.

3. Additional tightening of wiring system. Turn off the power source and tighten the following additionally: terminal inside the pressure switch, each terminal inside the magnetic switch box, power source terminal. Inspect carefully the parts, which are subject to large electric current. Further, dust attached to the magnetic switch contacts should be removed thoroughly.

4. Inspection and additional tightening of each bolt. Loosening of the bolts on the refrigerant circuit may cause refrigerant leakage and loosening of other bolts also cause unusual noise. Inspect each bolt carefully. If any bolts are found loosened, tighten them additionally.

5. Clogging of drain piping and cleaning of drain pan. Dust collected by the air filter sometimes falls on the drain pan and stains the drain pan or clogs the drain pipe. Therefore, clean them carefully.

Inspection Before Each Cooling Season.

Replacement of the protection zinc plate of the condenser and cleaning of the cooling tubes differ with quality of sea water or operating period more or less. However, it is advisable to inspect the condenser every 3 months opening the front and the rear cover of the condenser, and if necessary the protection zinc plate should be replaced or the cooling tubes should be cleaned.