Compressor Tightness Test; System Evacuation; Preliminary Checks - Pre-Starting - Emerson Copeland ZH04KCU Application Manuallines

5.2

Compressor tightness test

WARNING
High pressure! Personal injuries! Consider personal safety requirements
and refer to test pressures prior to test.
CAUTION
System contamination! Bearing malfunction! Use only dry inert gases (for
example nitrogen) for leak testing. DO NOT USE other industrial gases.
The compressor has been leak-pressure tested in the Emerson factory.
All compressors get a factory holding charge of dry air (about 1 to 2.5 bar, relative pressure). The
presence of 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.
Never add refrigerant to the test gas (as leak indicator).
5.3

System evacuation

Before the installation is put into commission, it has to be evacuated with a vacuum pump. The
vacuum pump and all tools have to be approved for R290 refrigerant/air mixture. 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.
When working on systems filled with refrigerant, it may be necessary to repeat the evacuation
process several times. Refrigerant may have dissolved in the refrigerant oil and will only gradually
condense out.
Preliminary checks – Pre-starting
5.4
WARNING
Air/R290 refrigerant mixture in a potentially flammable or explosive
atmosphere! Fire and explosion hazard! Whenever starting up a system
charged with R290 refrigerant, eg, after filling, repair, or maintenance, make
sure not to start and operate accidentally in a flammable or explosive
atmosphere.
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:
▪ no explosive atmosphere or flammable gas in the ambient;
▪ suitable ventilation according to room volume and refrigerant charge;
▪ 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;
24 AGL_HP_ST_ZHKCU_EN_Rev01