OPERATING INSTRUCTIONS
CO
2
/NH
3
CASCADE UNIT
250 - 1000 KW
44 _551511_om_kas_gbr_1_.doc
80% of its capacity. If this charge volume has not yet
been reached, although there is still refrigerant in
the system, the cylinder pressure can be reduced by
discharging gas from the cylinder.
For example, the cylinder's gas side can be relieved
via a hose connection with the service valve into the
suction line. If the cylinder is 80% full, the refrigerant
feed valve and the cylinder valve are closed and the
next cylinder is connected.
Repeat this procedure until all the refrigerant has
been bottled. The transferred refrigerant volume
must be documented.
After transferring the refrigerant into the cylinders,
reclose the feed (drawing in) valve.
The system is evacuated until it is completely
drained. After the extraction equipment has been
switched off no further pressure rise may occur.
4.4.4.3 Connections for draining refrigerant
NH
3
circuit
The NH
3
refrigerant circuit or circuit sections can be
drained via the following service valves:
— at the low-pressure level probe item (2875)
— the charging and draining valve in the liquid line
item (2865)
— the service valves in the suction line (gas side)
— the service valves in the oil return line
CO
2
circuit
The CO
2
circuit can be drained via the following
service valves:
Service valve in the pump discharge line item (6925)
Service valve in the injection line item (6865)
4.4.5 Venting the refrigerant circuits
Air which has penetrated the refrigerant circuit or
remains there due to incomplete evacuation, will
accumulate at the coldest point in the condenser
during operation, because it cannot be condensed.
The result is a pressure rise in the condenser by the
partial pressure of the air fraction. This leads to
increased energy consumption through to cut-off off
due to overpressure.
NH
3
circuit
Venting takes place during operation by means of
the service valve (installed on site) at the condenser
outlet.
Conduct the air into a water tank while the valve
slightly open so that residual ammonia is absorbed.
If necessary, change the water in the tank to ensure
the ammonia concentration does not lead to
nuisance/skin irritation, etc.
If the gas bubbles fully dissolve in the water there is
no air.
Eliminate the causes of air penetration.
CO
2
circuit
Venting of the CO
2
circuit can only take place via the
service valve item (6865) in certain circumstances.
The CO
2
air mixture when the system is at a standstill
should be drained to the outside in a controlled way
using the hose connected at the service valve.
Note and comply with the safety regulations for
handling the coolant.
4.5 Charging and draining oil (see also
putting into service)
4.5.1 General notes on handling refrigerator oil
Oil drained from the compressor may not be reused.
Always use fresh oil from sealed containers!
Make sure the oil cannot mix with other oil grades
or types.
4.5.2 Check oil level
The liquid level in the oil sight glass of the oil
separator should be between 1/2 and 3/4 of the
sight glass height.
4.5.3 Oil filling
Follow the compressor start-up and operating
instructions for refilling oil.
4.5.4 Draining, changing, checking oil
It may be necessary to drain the oil:
— to inspect or repair the compressor and
— if there is too much oil in the circuit
The oil in the cascade has to be changed:
— if the operating hours of the oil charge has
reached the oil changing interval based on
technical reasons
— if the oil was impermissibly contaminated due to
a breakdown or accident (e.g. intrusion of water
into the refrigerant circuit).
The serviceability and performance condition of the
refrigeration machine oil is assessed by a rough visual
inspection (contaminations) or laboratory analysis:
— after 5000 hours or
— at the end of one year's operation or
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