Fire safety requirements for electrical wiring and lighting equipment installation

Improperly installed electrical wiring in cold storage can also cause fires.

(1) During the design and installation of the circuit, the power supply line should not pass directly through a combustible insulating layer. For Jiangmen cold storage, it is recommended to pre-bury conduit sleeves on the door frame to allow the power supply line to pass through them. If it is necessary to pass through the combustible insulating layer, an additional conduit with protective casing is required, and the gap outside the casing should be filled with non-combustible materials such as asbestosis mud, glass fiber, basalt, or porcelain soil mixed with chlorinated paraffin, within a range of 20-50cm.

(2) Electrical wiring installed permanently in cold storage should be run through conduits. Lighting fixtures should be of moisture-proof type. It is prohibited to lay wiring directly within combustible insulation layers or to install switches inside the storage facility.

(3) To prevent the cold storage door and internal walkway from freezing due to low temperatures, affecting operation, the new design involves installing a flexible Constantan wire rubber heating cable (anti-freezing heating cable) within the door frame and beneath the walkway floor, which passes through copper tubes. The surface temperature can be controlled at 20°C with a voltage regulator. However, if installed incorrectly, leaving the power input junction outside the wall and allowing the anti-freezing heating cable to pass through rice hull insulation may cause overheating of the resistance wire, leading to a fire.

The correct installation method involves mounting the power junction box within the wall, and then using non-flammable insulating material to separate the conduit. The voltage for the anti-freeze heating wire should not exceed 36V, and the voltage regulator's adjustment range should be limited to a safe temperature.

(4) Temporary electrical wires for construction must be of rubber-sheathed cables and are not permitted to pass through combustible insulating materials. High-power lighting fixtures must not be placed close to flammable materials or insulation layers, and must be temporarily secured with a lamp stand. When construction is halted, the power supply should be disconnected.

Refrigerated storage

The primary principle of preserving cold storage is to inhibit the activity of microorganisms and enzymes. Wind-cooled preservation cold storage is a type of storage that extends the shelf life of fruits and vegetables, achieving preservation effects. The preservation temperature range for fruits and vegetables is between 0°C to 15°C, with different fruits and vegetables requiring different storage temperatures. They should be stored separately according to temperature. For example, cabbage, carrots, grapes, and apples should be stored at 0°C to 2°C, tomatoes, cucumbers, lichees, etc., at around 10°C, and bananas, lemons, pumpkins, etc., at 13~15°C.

In summary, excessively high storage temperatures accelerate the aging of fruits and vegetables, while excessively low temperatures can lead to chilling and freezing damage. Additionally, the humidity of the cold storage should also be considered.

2. Refrigeration systems and equipment selection for cold storage

For the design selection of refrigeration systems in the installation and construction of small cold storage, the main focus is on the choice of cold storage compressors and evaporators.

For small refrigerated warehouses, a fully enclosed compressor is the primary choice.

Typically, semi-hermetic compressors are used in medium-sized cold storage facilities, while refrigerated cold storage facilities and large cold storage facilities often opt for semi-hermetic compressors. For small cold storage facilities, due to their smaller size and other factors, fully enclosed compressors are more suitable.

For example, this small hotel cold storage, due to the small power of the fully enclosed compressor, it is relatively inexpensive and very suitable in terms of price for investments in small cold storage facilities. When selecting evaporators for the cold storage design of small cold storages, medium and low-temperature cold storages primarily use evaporator pipes made of seamless steel tubes, which feature excellent constant-temperature effects, can preserve freshness at constant temperatures, and can store cold energy at appropriate times; for high-temperature cold storages, cold fans are used as evaporators, characterized by rapid cooling, but they may also cause moisture loss in stored products.