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Conceptual and Legislated Design Considerations for Emergency Warning Systems in Industrial Facilities

Emergency Warning Systems (EWS) are a necessary part of any industrial facility. Statistics indicate it is not a matter of “if” there will be a plant emergency, but “when.” Thus, the EWS ensures that …

Emergency Warning Systems (EWS) are a necessary part of any industrial facility. Statistics indicate it is not a matter of “if” there will be a plant emergency, but “when.” Thus, the EWS ensures that injuries to people, damage to the environment and to plant infrastructure are kept to a minimum. There are as many philosophies about EWS design as there are types of plants. There are fundamental considerations, however, that must be taken into account before constructing a new facility. In addition, there may be known deficiencies in the EWS in existing plants, which owners have an obligation to rectify.

Corporate responsibility

Most industrial organizations have clearly stated health, safety, and environmental policies. They have an internal mandate to protect the health of workers and neighbours. They have a mandate to provide a safe working environment, and finally, they have a mandate to protect the environment from spills, discharges, and waste. It is clear that the three prongs of the HS&E policies are intricately related. They set the tone and direction, and provide some of the details required through specific sub-policies. The problem with the policies, however, is that they are often too general and fail to address the “how” and “what” to do in the event of an emergency.

We have seen over the years how acceptable standards of workplace HS&E have changed. People and the environment are protected from process discharges; they wear protective clothing and other equipment. Actions that were previously allowed are now forbidden. Safety has become a culture within organizations, generally driven from the top down, but in collaboration with front-line employees, special interest groups, and non-governmental agencies (NGOs).

Despite the improvements we have made, there is room to become better. The U.S. Chemical Safety & Hazard Investigation Board, investigating a 2006 fire and explosion in a plant which produced polyvinyl chloride (PVC), found that during a release of vinyl chloride monomer (VCM), workers failed to perform as per the requirements of the Emergency Response Plan (ERP). Five workers were killed, three were injured and the surrounding community was evacuated for two days. VCM is both flammable and carcinogenic. While there were conflicting instructions within the ERP, workers failed to evacuate the area, failed to don protective breathing apparatus and failed to activate emergency alarms. There was no automated mechanism to notify neighbours. The facility had not had a large release training exercise in over ten years.

The Board recommended that the company “clearly characterize emergency scenarios, address responsibilities and duties of responders, describe evacuation procedures, and ensure adequate training.” The cause of the accident is listed as human error. The plant has not been rebuilt.

In 1989, an explosion and fire killed 23 and injured 314 in a U.S. petrochemical plant. Debris was scattered over a six mile radius. The U.S. Fire Administration & National Fire Data Center investigation showed that human error during maintenance was the cause. In total there were about ten explosions over the duration of the crisis. There was no gas detection or audible alarm system in place in the area where the gas leak and explosion took place. Employees were not familiar with emergency evacuation procedures, yet had only 60 – 90 seconds to make life and death decisions. The lack of functional EWS in the affected area resulted in a “run for your life” response from workers.

The investigators further found that incoming telephone calls jammed the phone lines and delayed broadcasts on the EWS. Emergency personnel were tied up with the media and dealing with the public, rather than doing their jobs. Investigators also found that emergency personnel had incomplete information to broadcast. It is estimated the explosion caused approximately $1.5 billion in damage and lost production. The company was fined $4 million.

Legislated Requirements for Emergency Warning Systems Provincial

Provincial legislation is generally covered through the Occupational Health and Safety Act. In Alberta, this falls under the auspices of the Department of Human Resources and Employment. Some pertinent points from the Act are included here:

* Build an Effective Health & Safety Management System;

* Identify the types of disasters and emergencies;

* Assess the potential for harm;

* Develop procedures to deal with each type of emergency;

* Train workers to deal with each type of emergency;

* Install warning systems such as fire alarms;

* Install emergency equipment including emergency communication systems; and

* Practise

Federal

Federal legislation is covered through Human Resources and Social Development Canada, and the Canada Occupational Health and Safety Regulations Part 10 – Hazardous Substances:

* Where reasonably practicable, the employer shall provide automated warning and detection systems where the seriousness of any exposure to a hazardous substance so requires.

International

The National Fire Protection Association (NFPA) takes things a little further. In its Annex E Mass Notification Systems, it states:

“NFPA 72 contains requirements that can impact the application of mass notification systems. Coordination of the functions of a mass notification system with those of a fire alarm system is essential in order to provide effective communication in an emergency situation. Conflicting or competing signals or messages from different systems could be very confusing to occupants and have a negative impact on the intended occupant response. Where independent systems are used, the mass notification system would need to interface with the fire alarm system to effect related control actions such as temporary silencing of notification appliances. The use of a single integrated combination system might offer both economic and technical advantages. In any case, coordination between system functions is essential.

“For the purposes of this annex, a mass notification system is considered to be a system used to provide information and instructions to people in a building, area, site, or other space using intelligible voice communications and possibly including visible signals, text, graphics, tactile, or other communications methods.”

The Health and Safety Executive (HSE) in the United Kingdom offers these requirements for non-verbal, auditory warnings:

All employees and contractors on site should know what each alarm means and what the required response is, if the cause of the alarm has the potential to affect them.

The design of the alarm system should prevent masking and flooding of alarms. Masking is where one alarm noise masks a similar sounding alarm, preventing the operator from detecting the signal. Flooding happens when a system alarms, which has a ‘knock on’ effect on other related systems, the result of which is the triggering of myriad other alarms, flooding the site with sound.

There should be a noticeable difference between alarm sounds used to alert, rather than for routine communication and information signals. The HSE also recommends using verbal auditory warnings, in conjunction with visual warning systems:

* Consider using verbal auditory warnings in combination with visual warnings. Use of both methods has been found to improve compliance with the warning message.

Finally, the U.S. Department of Labor, through the Occupational Safety and Health Administration, provides additional direction.

* An employer must have and maintain an employee alarm system. The employee alarm system must use a distinctive signal for each purpose.

*
The employee alarm system shall provide warning for necessary emergency action as called for in the emergency action plan.

* The employee alarm shall be distinctive and recognizable as a signal to evacuate the work area or to perform actions designated under the emergency action plan.

* The employer shall assure that all employee alarm systems are maintained in operating condition except when undergoing repairs or maintenance.

Now we know that we need “something” and we have some ideas about how it should work and what it should do. In Part 2, we will discuss how to put it all together for the real world.

For additional information contact: Paul Huene Accutech Industrial Systems Inc. PO Box 157 Irvine, AB, Canada T0J 1V0 P 403 834 3414 E paulh@accutech-industrial.com 2007