NetCol5000-A020 Air Cooled In-row Precision Air
Conditioner
User Manual
5 System Operation and Maintenance
Issue 01 (2014-06-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
77
(the indoor dry-bulb temperature is 37.8°C, the wet-bulb temperature is 20.8°C, and the
outdoor temperature is 35°C).
Suction Superheat Degree
A suction superheat degree has impact on the compressor service life. A compressor
permanently running at a very low or no overheat degree due to liquid strike. An excessive
superheat degree would affect system performance. The superheat degree should range from
6°C to 13°C.
Determine the suction superheat degree as follows:
1.
Measure the pipe wall temperature at the sensing bulb of thermostatic expansion valve.
2.
Measure the suction pressure and find out the saturation temperature by using the
measured pressure as the reference pressure inside the evaporator.
3.
Determine the difference between the temperature at the sensing bulb and the found
temperature as the suction superheat degree.
Thermostatic Expansion Valve
Rotate the adjustment screw rod within one circle each time. About 30 minutes are required to
achieve a new balance.
The thermostatic expansion valve adjusts the suction superheat degree. Perform maintenance
on the thermostatic expansion valve as follows:
1.
Check that the sensing bulb is securely installed.
2.
Check that no fracture exists on the sensing bulb and valve capillary tubes.
3.
Check that no crack exists at the welding points of the equalizer pipe.
It is not recommended that you adjust the thermostatic expansion valve onsite because it has
been adjusted before delivery. If the superheat degree is too low or high, adjust the
thermostatic expansion value as follows at your deliberation or after consulting Huawei
technical support:
1.
Unscrew the valve bonnet at the bottom.
2.
Rotate the adjustment screw rod clockwise to increase the superheat degree. Rotate the
adjustment screw rod counter-clockwise to decrease the superheat degree.
Sight Glass
To maintain the sight glass, perform the following steps:
1.
Check the sight glass. If the ground color is yellow, the cooling system contains
excessive water and requires maintenance. (You need to reclaim the refrigerant and
vacuumize the system to drain out the water.)
2.
If you find air bubbles with the sight glass, the cooling system lacks refrigerant. Adjust
the expansion valve or charge in refrigerant.
