Fire Detection in Cold Storage

Cold storage facilities are used extensively from production to storage for everything from food to pharmaceuticals to art work. Not only are these business critical facilities, expensive to build and run, but the assets they contain must be secured from all and any risk – and that includes FIRE

 

What is cold storage?

Any refrigerated storage area or building that is designed for the storage of items to be kept in an environment below the outdoor temperature, is considered cold storage.  While it is commonly used for food production there are many other goods that require environmentally controlled facilities, including pharmaceuticals, cosmetics and art work.

Cold stores can vary in size and construction, from small self contained rooms, to full warehouses storing thousands of tons of product.

The 4 main types of cold store are:

  • Coolers (0°to 18 °C)
  • Freezers or holding rooms (-23° to -15°C)
  • Sharp freezers (-37° to -18°C)
  • Chill rooms (-9° to -1.7°C)

Insurance companies are actively looking at the risks within cold store areas as the cost of damage to both the facility and the assets being stored can be massive.

Risks

Despite sounding illogical, given the cold conditions, storage facilities do carry a significant fire risk. When looking at fire risks the 2 primary factors to look for are risks of where and how a fire might start and what factors will increase the spread and growth of any fire.

There are many house keeping actions that should be taken to minimise the risks of any fire, but there are some prominent risks to look out for:

Dry Air

The laws of physics dictate that as the temperature of air drops, so does it’s capacity for holding water. This means that the air within cold storage facilities is extremely dry. The lack of moisture in the air not only makes a fire easier to start, but also more likely to rapidly spread.

Electrical Faults

Electrical fires are one of the most common starting point in most buildings, and cold storage is no exception. There is considerable machinery required to run a large cold store and each moving part and electrical connection is a potential risk. Good maintenance of electrical components is critical to reducing fire risk in cold stores.

Combustible Chemicals

Aside from the chemicals that may be being stored, there are often highly combustible substances used to operate the facility. Ammonia, for example, is a widely used coolant in the refrigeration industry, and is highly volatile. Safe storage and maintenance of such chemicals, and ideally isolation from other parts of the facility, will reduce the risk of the fire spreading.

Packing Materials

The assets the cold store is housing may itself be a fire hazard, but in addition to the stock the packaging can also be an issue. Highly combustible polystyrene or polyurethane foam or wooden pallets and not forgetting the cardboard and plastic packaging, can cause a small fire to spread very quickly.

Insulating Materials

The need to efficiently maintain proper temperatures in cold storage facilities is often achieved by adding insulation to the walls and ceiling of the building, but this can lead to exposed sprayed-on plastic foam. Fabrication of the cold stores to have fire retardant structures is a critical component of fire protection.

High Racking

While the stacking of goods might not necessarily cause a fire, the high stacking helps the fire to spread upwards as the hotter air surges skywards. Also when the goods are tightly packed the combination of the dry air, combustible packaging and potentially volatile chemicals are a recipe for disaster.

 

Detection Problems

In addition to the risks, cold stores also provide additional challenges to traditional fire detection:

Low Temperatures
Most electronics are not designed to operate in very low temperatures, and smoke detectors are no exception.
Most cost storage work outside the operating temperatures for standard electronic detection devices.

High Airflows
The high airflows created by blast chiller units hamper the operation of conventional “passive” detectors.
Any smoke in the area will be carried in the high airflow, not reaching the ceiling.

High Storage Racking
The racking can affect the airflow and impede the detection response.
Many warehouses are too high for point detection and the nature of the closely stacked shelves creates a chimney effect
Restricted Access
Often warehouses have tightly packed rows of shelves with narrow access corridors.
Or they are tightly insulated rooms . The sealed rooms trap the smoke and toxic fumes of the fire. This makes it dangerous to escape from and difficult for the fire services to enter the area to tackle the fire.

Solutions

In addition to good housekeeping and using fire retardant materials in the construction there are some options for fire detection in these areas.

AspiratioN

Aspirating or High Sensitivity Smoke Detection (HSSD) has a number of unique features that make them suitable for detection in cold stores:
Active Sampling
The active sampling nature of aspirating systems means they can provide early warning, reducing the risk of the fire growing and also minimising product contamination.
ABS Pipes
As the air sampling is done via holes in a pipe network, the air can be transported externally to a detector keeping the electronics out of the cold room*,
or back to an IP65 rated detector unit. The other advantages of having the detector mounted outside of the room is that it’s easier to see if there is an issue and it is much easier to work on.

*Note – where this is done an exhaust pipe must be returned back to the room and the use of water traps are advised.

Where the piping is fitted directly in the room heaters can be installed to stop the holes from freezing over. There is also the alternative option of mounting the pipes above the ceiling and dropping capillary sampling points into the room. This will largely depend on the construction of the room.

See manufacturers guidelines for recommended installation practice for your particular detector.

Stacking

Another good use of aspiration is the versatility of the pipe runs. As identified with high storage racking, the fires can build up through the shelving before escaping into the general area. Pipe design can be used to sample both vertical or horizontal sections of the racks before the fire has a chance to expand skywards.

Linear Heat Cable

Linear heat cable can provide reliable and cost-effective fire detection in areas with ambient temperatures as low as -50°C and is not affected by high airflow.


Linear heat cable is an excellent solution in harsh environments as the electronics can be located externally. Specific temperature alarm points be used as triggers depending on the choice of cable.

This method can be used to look for temperature changes in the general area, or used in close proximity to specific high risk equipment such as conveyor belts, or along shelving racks.

Linear heat cable can come protected in a variety of materials to suit the environment. The common options are:

  • Digital
  • Analogue
  • Fibre Optic
  • Pneumatic

 

 

 

 

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