Emerson PFH020A-L, User Manual

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System Testing And Maintenance
Liebert
®
Mini-Mate2
™
56
9.2 Maintenance
9.2.1 Electric Panel
The electric panel should be inspected on a semi-annual basis for any loose electrical connections.
9.2.2 Filters
Experience shows that filters are usually the most neglected item in an environmental control
system. In order to maintain efficient operation, they should be checked monthly and changed as
required.
Filters can be replaced by either opening the hinged door on the return air filter box or by opening the
return air grille (grille version only). Replacement filters are commercially available in several
efficiencies, refer to the Liebert Mini-Mate2 engineering manual, SL-10525, for appropriate filter
sizes.
9.2.3 Direct Drive Blower Package
Monthly inspection of the blower package include: motor mounts, fan bearings and impellers.
Fan Impellers and Motor Bearings
Fan impellers should be thoroughly inspected and any debris removed. Check to see if they are tightly
mounted on the fan shaft and do not rub against the fan housing during rotation. Although the unit's
motor bearings are permanently sealed and self-lubricating, they should be inspected monthly for
signs of wear.
Air Distribution
Since all unit models are designed for constant volume air delivery, any unusual restrictions within
the air circuit must be avoided. Note that high-efficiency filters can reduce air performance and
evaporator capacity.
Motor Replacement
If the evaporator motor needs to be replaced, first remove the air distribution plate on the bottom of
the unit. Removing the mounting screws, allows the entire blower wheel and motor to be lifted out.
9.2.4 Refrigeration System
Each month the components of the refrigeration system should be inspected for proper function and
signs of wear. Since in most cases evidence of malfunction is present prior to component failure,
periodic inspections can be a major factor in the prevention of most system failures. Refrigerant lines
must be properly supported and not allowed to vibrate against ceilings, floors or the unit frame.
Inspect all refrigerant lines every six months for signs of wear and proper support. Inspect the
capillary and equalizer lines from the expansion valve.
Suction Pressure
Suction pressure will vary with load conditions. Suction pressure normally ranges from 58 psi to 75
psi (405 kPa to 517 kPa).
Discharge Pressure
The discharge pressure will vary greatly with load and ambient conditions ( Table 24 ). The high-
pressure switch will shut the compressor down at its cut-out setting.
Table 24 Typical discharge pressure
System Design Discharge Pressure, psig (kPa)
Air-Cooled 200-300 (1380-2070)
Water-Cooled 65 to 85°F water
(18 to 29.4°C)
200-250 (1380-1725)
Glycol-Cooled 250-350 (1725-2415)
High-Pressure Cut-Out 400 (2760)