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LCE

RG66004766_rev.05

The lower limit is due to the limit of freezing temperature of glycol solutions with 35% of their weight made

of glycol, the maximum admitted by the tightness of the pumps used.

Minimum temperature

of produced water °C

5 2 -1 -5 -10

Weight percentage of

ethylene glycol %

0 % 10 % 15% 25 % 35 %

Freezing point of

mixture

0 -4 - 8 -14 -18

The heating elements of the oil sump of the compressor are supplied as a standard for the Free-Cooling

units. The "Oil" figure illustrates a specific property [Charles’ Law] of gases, which are more soluble in

liquids as the pressure increases but less soluble as the temperature increases: if the oil is held at a

constant pressure in the sump, an increase in temperature will significantly reduce the amount of

refrigerant dissolved in it, thus ensuring that the lubricating function desired is maintained. The problem

about poor lubrication, lacking adequate crankcase heating, occurs mostly after breaks where due to the

effect of the suction effect of the compressor the pressure in the slump suddenly falls and most of the

refrigerant previously dissolved in the oil evaporates. With no heating elements, this would lead to two

problems:

 Oil dilution and therefore inadequate lubrication.

 Migration of the oil towards the cooling circuit due to the refrigerant dragging effect.

Use of electrical resistances is extremely important especially at the first start-up. It is recommended to

leave them inserted for at least 12 hours before starting the compressors.

If the outside air T drops considerably, the water T inside the system is controlled by the modulating

action of fans and in extreme circumstances (strong prevailing winds) by the closure of the 3-way valve.

produced

water

T outside

13°

10°

5°

-18° 42° 44°

fig. “oil”

Pressure

within the

crankcase

% of R410A dissolved in oil

Oil T