Emerson COPELAND ZO18AG, Инструкции по применению

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22 AGL_Ref_ST_ZO_E_Rev00
All compressors get a factory holding charge of dry air (about 1 to 2.5 bar, relative pressure). An
intact holding charge serves as a proof of quality against penetrating moisture.
When removing plugs from the compressor, the plugs may pop out due to pressure and oil can spurt.
Any later modification to compressor connections can have an impact on the compressor tightness.
Always leak-pressure test the compressor after opening or modifying the connections.
5.3 System evacuation
Before the installation is put into commission, it has to be evacuated with a vacuum pump. The
installation should be evacuated down to an absolute pressure of 3 mbar. Proper evacuation reduces
residual moisture to 50 ppm. During the initial procedure, suction and discharge shut-off valves on
the compressor remain closed. The installation of adequately sized access valves at the furthest
point from the compressor on the suction and liquid lines is advisable. The pressure must be
measured using a vacuum pressure gauge on the access valves and not on the vacuum pump; this
serves to avoid incorrect measurements resulting from the pressure gradient along the connecting
lines to the pump.
Evacuating the system only on the suction side of a scroll compressor can occasionally result in a
temporary no-start condition for the compressor. The reason for this is that the floating seal could
axially seal with the scroll set, with the higher pressure on the floating seal. Consequently, until the
pressures equalise, the floating seal and scroll set can be held tightly together.
The highest demands are placed on the leak-proof design of the installation and on the leak testing
methods
– please refer to EN 378.
5.4 Preliminary checks
– Pre-starting
Discuss details of the installation with the installer. If possible, obtain drawings, wiring diagrams, etc.
It is ideal to use a check-list but always check the following:
▪
visual check of the electrics, wiring, fuses etc;
▪
visual check of the plant for leaks, loose fittings such as TXV bulbs etc;
▪
compressor oil level;
▪
calibration of HP & LP switches and any pressure-actuated valves;
▪
check setting and operation of all safety features and protection devices;
▪
all valves in the correct running position;
▪
pressure and compound gauges fitted;
▪
correctly charged with refrigerant;
▪
compressor electrical isolator location & position.
5.5 Charging procedure
CAUTION
Low suction pressure operation! Compressor damage!
Do not operate
with a restricted suction. Do not operate with the low-pressure limiter bridged.
Do not operate compressor without enough system charge to maintain at least
6 bar(a) suction pressure. Allowing pressure to drop below 6 bar(a) for more
than a few seconds might cause CO
2
solidification and blocked valves or
pipes. Do not operate compressor at pressures that are not allowed by the
operating envelope. Allowing the suction pressure to drop below the envelope
limit for more than a few seconds may overheat scrolls and cause early drive
bearing and moving parts damage.
Prior to charging or re-charging, the refrigerant system must be leak- and pressure-tested with
appropriate purging gas.
Ensure that the system is grounded prior to charging with refrigerant.
Ensure charging equipment is approved for at least 90 bar. Charge the system with vapour CO
2
up
to a minimum pressure of 6 bar(a) to prevent forming of dry ice. Then continue with charging liquid
CO
2
. The system shall be charged through the liquid-receiver shut-off valve or through a valve in the
liquid line. The use of a filter drier in the charging line is highly recommended. Systems shall be
liquid-charged on both the high and low sides simultaneously to ensure a positive refrigerant
pressure is present in the compressor before it runs. The majority of the charge shall be placed in
the high side of the system to prevent bearing washout during first-time start on the assembly line.
Extreme care shall be taken not to overfill the system with refrigerant.