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System Operation and Maintenance 51
6.5. Cooling System
1. Check the refrigerant pipes and fixing brackets every six months; the refrigerant pipes must have proper brackets, and
it is not allowed to lean against the wall, the floor or the fixed frame where it vibrates; at the same time, it is necessary to
check whether the pipe insulation cotton is damaged. If any, cotton needs to be refilled in time.
2. The components of the cooling system must be inspected monthly to see if the system is functioning properly and for
signs of wear. Since the device failure or damage is often accompanied by corresponding failures, regular inspections are
the main means to prevent most system failures.
3. The refrigerant pipeline must have proper support, and it is not allowed to lean against the wall, floor or fixed frame
vibration. Check the refrigerant pipeline and fixing brackets every six months.
4. Each system is equipped with a sight glass, which is convenient to observe the flow of liquid refrigerant and the moisture
content of the system. When the moisture content in the system exceeds the standard, the background color of the sight
glass changes from green to yellow. When there are too many bubbles in the sight glass, the refrigerant charge may be
insufficient.
5. When the refrigeration system fails, the fault can be judged according to some parameters of the system operation.
6.5.1. Suction Pressure
When the suction pressure drops below the protection value set by the low pressure sensor, it may cause the compressor to
stop. On the other hand, too high suction pressure will also reduce the cooling of the compressor motor by the refrigerant,
which may cause damage to the compressor. The minimum (low pressure alarm setting) and the maximum (design
operation) suction pressure settings are shown in Table 6-3 .
Table 6-3 Suction Pressure
System
Minimum pressure
kPa (PSIG), R410A
Maximum pressure
kPa (PSIG), R410A
Air cooling (speed controller stepless speed regulation) 370 (53.7) 1580 (229)
6.5.2. Exhaust Pressure
The exhaust pressure may increase or decrease due to load conditions or condenser efficiency. When the exhaust pressure
reaches the set value of the pressure switch, the action of the high pressure switch will stop the compressor. Refer Table 6-4
for more details.
Table 6-4 Exhaust Pressure
System Design kPa (PSIG)
High pressure switch action value 4100 (595)
6.6. Terminal Electronic Expansion Valve
The automatic adjustment of the electronic expansion valve ensures that enough refrigerant is supplied to the evaporator to
meet the requirements of loading conditions. By observing and measuring the temperature of superheat and the opening of
the electronic expansion valve , user can determine whether the electronic expansion valve is operating normally.
Note: The temperature of suction superheat has a greater impact on the compressor life. If the compressor has run for a
long time under the condition of low or no suction superheat, it may cause the compressor to produce “liquid impact” and
break the scroll of the scroll compressor.
Note: If abnormal opening or adjustment of the electronic expansion valve is found at the application site, contact Vertiv
local representative and Vertiv technical support.