What are the requirements for adding refrigerant to air-cooled screw units?

After the air-cooled screw unit passes the vacuum test, the vacuum state in the system can be used for refrigerant filling
.

So what requirements do we need to meet when adding? 1, refrigerant filling For the newly installed system, refrigerant
can be added from the high-pressure side.

The operation method is as follows: (1) open the condenser cooling water system to keep the valve in the system in a vacuum test state
.

(2) 14mm×2mm seamless steel pipe (copper pipe should be used when filling freon) to connect
the cylinder with the refrigerant.

The cylinder mouth is tilted downwards, the cylinder is at a 30° angle with the ground, or the height of the barrel tail pad is about
200 ~ 300mm.

(3) Open the filling valve
.

When the system reaches a certain pressure (ammonia system 0.
1 ~ 0.
2MPa, Freon system 0.
2 ~ 0.
3MPa), stop filling the refrigerant, and then check the sealing of each connection point and welding point of the system
.

If there is no leak, continue to fill with refrigerant
.

(4) Close the liquid discharger valve on the reservoir and continue to fill with refrigerant
.

When the cylinder pressure is in equilibrium with the pressure in the reservoir, open the outlet valve
on the reservoir.

(5) Make the air-cooled screw unit enter the operating state, and continue to fill the refrigerant
.

When white frost appears in the lower part of the cylinder, it indicates that the liquid refrigerant in the cylinder is close to full
.

At this time, the cylinder valve and the inflation valve can be closed, and the cylinder can be replaced to continue inflation
.

(6) Unless the outside temperature is very low, it is generally not necessary to pour hot water on the cylinder to increase the pressure inside the cylinder when filling the refrigerant, because it is unsafe
to do so.

If you need to speed up the filling speed, the hot water temperature must not exceed 50 ° C, and other methods of
heating the cylinder are strictly prohibited.

(7) When filling with freon, a filter drier must be set on the dedicated connecting tube to reduce the possibility of
moisture entering the system.

When the high-pressure section is filled, the compressor must not be started, and the exhaust valve must not leak, otherwise a liquid hammer
will be generated.

(8) When the air-cooled screw unit refrigerant is injected to 90% of the filling capacity, the filling work can be temporarily stopped, the system trial operation can be carried out, and the system dose can be checked to meet the operating requirements to avoid unnecessary trouble
caused by too much injection.

For older refrigeration systems, if refrigerant needs to be replenished, it should be filled
from the low pressure end.

2.
Leak detection after filling (1) The test strip leak detection method generally adopts the weld, flange, thread interface, etc.
of the phenolphthalein test paper detection system, and the test strip is wet and close to the test site
.

If it turns red, there is an ammonia leak (be careful to avoid the illusion caused by the contact of the test strip with soapy water on the pipe
).

You can also use litmus test strips
that turn blue when you encounter ammonia.

(2) Halogen blowtorch leak detection halogen blowtorch is a common tool
for leak detection in Freon refrigeration system.