INTRODUCTION
Cold stores operate at various temperatures below freezing. Air temperatures may be as low as minus 30°C. The hazards associated with such harsh environments include :
- accidental locking in
- accidental release of refrigerant
- cold injury
- I increased risk of accidents
- special medical risks
- ice build up
- increased risk of equipment failure
Work in cold environments will therefore require risk assessment under the Management of Health, Safety and Welfare Regulations 1992.
SAFEGUARDS AND PRECAUTIONS
1. Cold stores should meet the standards in BS 4434 'Specification for safety aspects in the design, construction and installation of refrigerating appliances and systems' (1989)
2. Precautions against locking in to include :
-
Only authorised and fully instructed people allowed in
-
'No unauthorised entry' signage
-
At least 1 emergency exit, adequately signed and unobstructed
-
A trapped-person alarm, mains operated with battery back-up, suitably marked and located
-
Emergency lighting (battery operated)
-
Maintenance and testing of devices provided
-
Working practices to include thorough check before locking
3. Refrigerant Release : General precautions include -
-
Proper maintenance and operation by trained and competent person(s)
-
For plants exceeding 25kW, to have a written scheme for the periodic examination, by a competent person, of protective devices, pressure vessels and pipelines, and parts of pipework in which a defect may give rise to danger (See Pressure Systems element of this manual)
-
Written emergency procedure, communicated to all appropriate staff
Refrigerants can be classified into 3 main groups as follows :
|
GROUP |
EXAMPLES |
HAZARDS & PRECAUTIONS |
|
1 |
Halocarbons |
-
Stable, low toxicity and flammability favourable thermo physical properties and compatibility with other materials.
-
Toxic decomposition products may result from contact with flames or hot surfaces.
-
Can displace oxygen and cause suffocation.
-
Vapour detector and alarm.
-
Ventilation fans to operate if the concentration in the plan room exceeds the occupational exposure limits
|
|
2 |
Ammonia |
-
Toxic and flammable
-
Vapour detector and alarm
-
Ventilation fans to operate if the concentration in the plant room exceeds 1% (V/V)
-
Detailed advice is contained in Guidance Note PM 81: "Safe Management of ammonia refrigeration systems
|
|
3 |
Ethane, propane, butane, isobutane, ethylene, propylene. |
-
High flammability/explosion risk
-
Vapour detector and alarm
-
Ventilation fans to operate if the concentration in the plant room exceeds 25% of the lower explosive limit
|
For Groups 2 and 3 refrigerants, the vapour detectors should also isolate all unprotected electrical circuits.
Electrical equipment likely to operate in flammable concentrations should comply with the requirements for hazardous (potentially explosive) areas.
Self-contained or airline breathing apparatus should be provided where refrigerant vapour is likely to be present at a significant level (selection, maintenance, examination and testing, training implications).
4. Working at low temperatures :
-
Provision of suitable thermal/protective clothing
-
Access to warm rooms with hot drinks for breaks, the length and frequency of which will depend on the nature of the work, the working temperature and exposure time.
-
Cabs of any lift trucks to be heated and enclosed.