HSO 2024 to HSO 2035 Installation, Operation and Maintenance Manual
Issue 1.2 : 03/10
Publication 2-119
Page 59 of 94
The specimen log sheet illustrated in Appendix 5 Plant
Performance Record shows the minimum number of readings
which should be taken to enable an accurate assessment of the
plant’s performance to be made. In the case of a very large plant,
many more readings need to be logged to complete the overall
picture.
Particular attention should be paid to the following readings:
•
Oil temperature measured at the oil cooler outlet (if an oil
cooler is fitted instead of liquid injection).
•
Oil pressure at the compressor oil injection connection.
•
The net oil pressure drop across the oil filter.
•
Suction and discharge pressures and temperatures.
Gauge and temperature readings should be checked regularly, in
addition to routine logging, and any variations from normal
promptly investigated.
13.5.2. Weekly
(a)
Check the plant for refrigerant and oil leaks; refer to Leak Detection
in the publication for the refrigerant in Section 5.
While checking for leaks, inspect the exterior of the plant for
damage or corrosion.
(b)
Check that capped valves have their caps firmly in position to
prevent tampering, loss of refrigerant or the entry of air and
moisture.
(c)
Not usually applicable to plants charged with ammonia (R717),
applicable to all other refrigerants.
Check the sight-glass/moisture indicator. If there is evidence of an
increase in the moisture content of the system, corrective action
must be taken immediately by changing the refrigerant filter/drier
cores, and tracing and rectifying the cause of moisture ingress.
(d)
Applicable to plants charged with ammonia (R717), not applicable
to other refrigerants.
Unless the system is fitted with an oil still which automatically
returns oil to the separator/reservoir, it is usually necessary to
manually drain oil from vessels in the LP side of the system
(suction separator, flooded evaporator or plate heat exchanger). If
there is very little oil to drain, this period can be extended.
Turbulent conditions inside these vessels when the plant is
operating tend to distribute the oil in droplet form throughout the
body of liquid ammonia. It is necessary to stop the plant and wait
for the oil to collect in the bottom of the vessel before draining off.
WARNING
The greatest care must be taken when using external
drain valves. Protective clothing, gloves, goggles and a
respirator must be worn.
(e)
On multi-compressor applications, changeover the role of lead, lag
and/or standby compressor.
13.5.3. Monthly
(a)
Check the operation of the compressor capacity control system;
refer to 4.8. MSI Linear Variable Displacement Transducer (MSI
LVDT)
(b)
If a secondary oil separator is fitted in the discharge line, check the
pressure drop across the secondary oil separator. If the pressure
drop exceeds 0.7 bar, change the filter elements.
