Refrigeration plant is a significant investment. Relatively simple measures can be taken to protect and extend its life.
By Alan Jackson, BJA Refrigeration Consultants
EU 517/2014 (F-gas Regulations) will enforce reductions in the supply of high GWP refrigerants – measured in TCO2e, it is recommended that operators seek advice on existing equipment and where possible explore the opportunities to replace the refrigerant for one that has a lower global warming potential (GWP).
If refrigerant replacement works are engaged, following the recovery of the existing refrigerant, it is recommended that all elastomeric seals; liquid level receiver gaskets, solenoid valve seals and system flange seals are replaced. Following replacement, best practice should be followed with a vacuum being applied to remove air, other non-condensable gases and residual moisture from the system.
It is also important to monitor the quality of liquid refrigerant at the site glass, once settled there should be no bubbles present at the site glass that may indicate flashing-off. The system can then be leak tested, once system integrity has been established, a permanent and clear label identifying the systems refrigerant and oil types must be fitted.
Though not a new initiative a wise investment to existing plant is to fit a compressor inverter to control the otherwise fixed speed of a compressor motor. An inverter reduces the number of stop-start cycles that contribute to excessive wear and breakdowns.
Alarm and monitoring
An alarm and monitoring system provides a constant data stream of performance, energy consumption and system errors. Because the data is collected in real time, it is not only possible to maintain system operation at a visible and optimum level, but it can also be used forecast faults and address them as performance drifts beyond its set point parameters.
The appointment of a refrigeration service provider is carefully considered, aspects taken into account by end users include a contractor:
- Ability to respond within an agreed time scale in the event of a plant fault
- Understanding of your business needs
Plant investment should be viewed for the long term, and as such it would be sensible to invest time in a collaborative working relationship between operator and service provider.
- Interrogate the alarm log on the monitoring system daily; some reoccurring alarms may need further investigation by your service provider, others may be nuisance alarms, an example of this is an over temperature cold room due its door being left open
- Via the alarm and monitoring system, note the suction pressure and temperature, and compare these to the set-point parameters
- Ensure that there is nothing obstructing access to plant
- Cleanliness of plant – with particular emphasis on the condenser fins
- Ensure condenser fans are operational
- Ensure there is no excessive vibration
- Integrity of pipe work to and from the refrigeration plant (look out for excessive vibration)
- Listen out for unfamiliar noise as this could be a sign of bearing wear
- Inspect visual alarm lights
Where concerns arise from these checks, an operator should consult their service provider.
- A thorough refrigerant leak inspection (dependant on the potential of a refrigerants TCO2e, this may require this inspection to be at a more frequent interval)
- Inspection and testing of all safety devices, with confirmation of operation of all evaporator high level cut outs, oil failure, low pressure cut out, high pressure cut out, oil temperature cut out, high discharge temperature cut out, receiver safety device and all temperature controls
- Compressor oil changes
- Inspection of plant headers
- Condenser maintenance – including a full clean of the fins to ensure good air flow
- Inspect and clean all condensate drains
- Check for dirt or ice formation on evaporators – clean / initiate defrost as necessary
- An inspection of all electrical control terminals and connections
- A review of the alarm and monitoring system to ensure operation is commensurate with the outside temperature
- Ensure the system is adequately charged with refrigerant
- Replace suction filter and liquid line drier cores
Different levels of service contract exist, with the most desirable being a fully comprehensive one. Typically, these include all works plus the labour and material content of any breakdowns and repairs during normal working hours. This is particularly useful in allowing an operator to accurately forecast their monthly and annual maintenance expenditure, and, of course, provides complete peace of mind.