Focus on worker protection needed to ensure safe industrial growth and rise in ammonia use

By Huiting Jia, Sep 20, 2013, 13:06 4 minute reading

Widely reported ammonia leaks in China highlight the need for adequate training and stringent safety controls across the burgeoning cold chain sector. As developing countries switch from HCFCs to climate and ozone friendly ammonia as the refrigerant of choice for industrial refrigeration, appropriate checks and balances are needed to safely manage the chemical.

Although the mishandling of ammonia can cause harm, with the right procedures and technology in place, ammonia can be handled safely without incident. As the number of facilities that rely on ammonia for refrigeration increases, safety improvements are needed, in particular in countries and regions experiencing rapid industrial growth. 
Blocked fire exists and lack of personnel training lead to fatalities
Incidents like the ammonia leak that occured at Weng’s Cold Storage in China, a company in Baoshan district that specialises in frozen food processing, transportation and storage, and the ammonia leak and explosion in a slaughterhouse in Jilin province can be avoided if safety regulations are adhered to. 
Both ammonia leaks were due to employer and empolyees not following the prescribed safety procedures and lack of understanding of safety regulations.  While an initial investigation attributed the ammonia leak in Shanghai to loose pipe fittings, investigators also found blocked fire exits, and a lack of worker training, according to a statement from the Shanghai work safety supervision bureau. The explosion in Jilin Province was caused by an electrical short circuit, which inginted combustible workshop material, but many workers inside the plant found exits were locked. The lack of emergency fire evacuation drills meant staff did not know where the exists were located.
As the Chinese government works to reduce the number of workplace injuries and deaths, the incidents in Shanghai and Jilin attest to the need to enforce safety standards in the growing ammonia refrigeration sector.
Safe practices for ammonia refrigeration facilities
In refrigeration facilities ammonia is found throughout the plant, in the pressurised receiver, compressors and piping. The following series of recommendations can help to ensure its safe use: 
  • Use only compatible materials: all containers, piping, valves, and fittings contacting ammonia must only be constructed of iron, steel or other ammonia-compatible materials, as ammonia is corrosive to even trace amounts of copper, zinc, silver, and many of their alloys. 
  • Detectors: leak detectors should be installed, in particular if facilities are unstaffed for periods of time.
  • Training: it is important that personnel understand the properties of ammonia and that they be thoroughly trained in safe practices for its storage and handling.
  • Protective equipment: proper protective emergency equipment should be easily accessible in case ammonia is released. Appropriate respiratory, eye, and skin protection are essential as well as emergency equipment that includes eye-wash, shower facilities and first aid kits. Employees should have immediate access to these items, be properly trained in the use the equipment and must know how to use them in case of emergency. 
  • Written emergency procedures and drills: workers need to be provided with detailed directions in case of an emergency. Employers must also conduct emergency drills to determine whether the procedures work in practice and to thoroughly familiarise workers with their roles in an actual emergency. What is more, employers should keep records of these drills to monitor efficiency.
  • Emergency controls:  are needed to shut down the ammonia compressors, and must be located outside the machine room.
  • Exits: cold storage rooms must have doors that open easily from the inside, and should have a means of alerting other workers if a person is unable to exit the room.
NH3/CO2 systems help to reduce ammonia charge, increasing safety
In order to increase safety, some new cold stores are limiting the use of ammonia in their refrigeration facilities, investing in NH3/CO2 cascade systems. 
NH3/CO2 cascade systems have been used for low-temperature cold stores and freezing systems in several plants in the food industry. To end users in China, the NH3/CO2 cascade system is an innovative refrigeration method that combines the benefit of two natural refrigerants. Arrangements where ammonia is used as the primary refrigerant and CO2 has been adopted either as the secondary refrigerant and/or in the low temperature part of a cascade system helps to reduce the ammonia charge but also has the added advantages of low capital cost and high efficiency. A CO2-NH3 cascade system is considered an ideal solution for the Chinese cola chain, with the NH3 limited to a small charge that can be contained in a special machinery room that meets the necessary safety requirements. 


By Huiting Jia

Sep 20, 2013, 13:06

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