ammonia site evacuation

Ammonia Site Evacuation

To stay or not to stay?

Adam Bowey - Grenco Refrigeration Ltd.

To Stay or Not To StayAGENDA

• Ammonia Emergency Evacuation Procedures

• Ammonia Emergency Evacuation –Training Validation

• Ammonia Procedure• Case Studies:- To stay or not to stay?


Ammonia Emergency Evacuation Procedures

• Why do we need an emergency evacuation procedure?

• Safety devices and strict design makes the risk of a leak very small, however additional measures must be in place in the unlikely event of a major ammonia leak.



• How will I know that there has been an ammonia leak?

• Leak sensors are sited all round the refrigeration plant, in the event of a leak an alarm will sound.

• An announcement will be made to all staff. The announcement will advise the course of action to be followed. On no account are you to leave the building until you are told to do so.



• Will I be able to smell ammonia in the main building?

• Probably not, if a leak does occur it is most likely that it will be in the refrigeration plant room or in the roof void. These areas have automatic extract ventilation that will discharge ammonia at roof level, ammonia gas is lighter than air it will disperse in the atmosphere.

• What if I smell ammonia where I am working?

• Evacuate to the nearest adjacent room with your colleagues and report the incident. Note that ammonia can be detected by smell at very low concentrations, much lower than those that cause harm This provides useful early warning system



• Why do we not evacuate the building?

• Ammonia is a liquid, which very quickly turns to gas when it comes in contact with air, and as such will be carried by any wind. Depending on the area the leak is and in the direction of the wind, you may be able to continue working, or you may be asked to assemble in a particular area of the building, as it may be safer to stay inside.

• Where will we assemble?

• There are designated site assembly points. Adam Bowey - Grenco Refrigeration

Ltd.


• How will we know where to assemble?• The assembly point you have to go to will depend on the wind

direction because ammonia is a gas. The announcement will tell you exactly which assembly point you have to go to. Remember the direction of the wind will not always be the same.

• If we evacuate what route do I use?• Unlike a fire evacuation you may not be able to use the most

direct or quickest route to an evacuation point, you will be given clear directions at the time as to which route you should use.

• Do remember that as with a fire evacuation, you must not stop to collect personal belongings, run, or re-enter an affected area or the building until you have been given clear instructions that it is safe to do so.



• What part do the emergency services have in this procedure?

• In the event of ammonia leak the Fire Brigade will be called to site, on arrival the Senior Fire Officer will assume command of the situation and will advise management on staff movements around the site, and will issue instructions to the maintenance contractors with a view to making the plant safe.

• I am a driver what do I do?

• In the event of a leak a member of the emergency team will collect company drivers and direct them to an assembly point.

• The emergency team will collect 3rd party drivers and direct them to an assembly point.



SUMMARY:• Ammonia leak incidents are rare.

• Assembly Points and Evacuation Routes will be announced

• Listen carefully to all Assembly and Evacuation instructions.

• Do not evacuate the building unless instructed to do so.

• If assembly or evacuation is ordered ensure that you are aware of the appropriate Assembly Point(s) and the Route(s) to take to evacuate the


AMMONIA EMERGENCY EVACUATION Staff Training Validation

• How will you know if there has been an ammonia leak?

• In the event of an ammonia leak what will you do?

• Where are the ammonia leak assembly points inside the building?

• Where are the ammonia assembly points outside the building?

• How will you know which point to go to?

• What dictates which assembly point you have to go to?

• You must not do what, until given a clear instruction?

• Trainees Signature: ______________________________________


Ammonia Procedure• 1.0 Introduction

• In the unlikely event of a serious leak of ammonia it is vital that immediate action is taken to minimise risk to life or property.

• To this end the site that has ammonia refrigeration shall produce Ammonia Alarm - Emergency Response Instructions

• In general the procedure for this site regardless of staffing or configuration shares the essential steps of internal notification, external notification and evacuation.


Ammonia Procedure• 2.0 Probability of Ammonia Leaks

• The food manufacturer’s ammonia refrigeration system is designed, built, maintained and inspected to strict regulatory and industry standards. Catastrophic failure or serious leaks in plants to these standards are very rare. Ammonia plants are constructed entirely from steel pipework that is much less prone to leakage than the copper pipework normally used with other refrigerants.

• Minor leaks, mainly in the refrigeration plant room (less often in the condenser location) occasionally occur. These leaks are usually from shaft seals, pipe flanges or valve stems. Plant rooms containing ammonia equipment are fitted with ammonia sensing alarms that automatically start ventilation systems that vent ammonia gas to atmosphere.


Ammonia Procedure• 3.0 Ammonia Hazards

• Ammonia gas is toxic and in a fairly narrow band of concentration with air (160,000 to 270,000ppm by volume) is flammable and explosive.

• Ammonia’s pungency is however a significant advantage as it can be detected by smell at concentrations of 5ppm upwards and therefore warns personnel against remaining in a harmful concentration.

• Short term exposure to concentrations of about 200ppm will causeirritation and discomfort to the mucous membrane and the eyes but with no lasting consequences. Exposure to concentrations above 1500ppm will damage or destroy body tissue whilst exposure to 2500ppm and above increases the risk of fatality


Ammonia Procedure• 4.0 Ammonia Leak Detection

• Automatic Leak Detection is installed in refrigeration plant rooms and where applicable in roof voids via two stage alarms: -

• Level 1: - This level is set at a maximum 500ppm

• Level 2: - This level is set at a maximum 30,000ppm (3% by volume) and denotes a major leak.

• Human Leak Detection at 5ppm upwards is more sensitive than the automatic equipment and provides a valuable early warning system


Ammonia Procedure• 5.0 Plant and Equipment• The design and operation of ammonia refrigeration plants is

subject to number of regulatory and standards requirements including, but not limited to: -

• HSE Guidance Note PM81 (Published 1995) • Construction (Design and Management) Regulations 2007 • Pressure Systems Safety Regulations (2000) – Written Scheme

of Examination required• EC Pressure Equipment Regulations 1999 (PED)• BS EN 378:2008 Parts 1/2/3/4 Refrigerating Systems and Heat

Pumps – Safety and Environmental requirements. (Part 1 not issued)

• Institute of Refrigeration – Safety Code for Compression Refrigerating Systems Utilising Ammonia (under revision)


Ammonia Procedure• 6.0Emergency Response Procedures

• On actuation of alarm, emergency team informed.

• Call out to specialist refrigeration contractor. • Emergency team call fire brigade.• Establish wind direction and tailor evacuation

plans accordingly. (wind sock)• Emergency team will announce on the action

to be taken.


Ammonia Procedures• 6.0 Emergency Response (continued)

• Emergency team will check ventilation systems, doors and windows.

• Ammonia alarm sounder must be different from fire alarm • Call an ambulance if aware of injuries and ensure access

available for emergency vehicles.• Emergency team and specialist contractor must stand by to

assist fire brigade• Specialist contractor may effect repairs if safe • Employees and visitors must ONLY return to evacuated areas

after being instructed to do by emergency support team or fire brigade.

• Additional procedures will be required for out of hours


Ammonia Procedure• 7.0 Ammonia Emergency Action Plan

• Isolation of the leak and the rescue of any persons in the leak area with the assistance of the emergency services

• Location of plant rooms and associated pipework– Site general arrangement plan of ammonia plant and pipework. – Plant emergency shut down procedure– Risk Assessment of each area showing what action should be

taken if ammonia leak occurred in area; include details of fans and means of escape.

• COSHH assessment sheets and manufacturer safety data sheet for ammonia

• First aid treatment to be administered in the event of exposure


CASE STUDY No 1 • Site Layout (Chilled Cold Store)- Large Industrial Estate, With Ammonia Plant

Room At Rear Of Store.- Access Road To Factory Runs Parallel To

Ammonia Plant RoomWhat Happened:-Plant room contained ammonia / glycol heat exchangers. A heat exchanger split leaking ammonia content (1,000kg) onto the plant room floor.


CASE STUDY No 1 (Continued)

• Refrigeration contractor was on site working on the refrigeration plant.

• Action / ResponseThe plant room was evacuated and the relevant duty manager notified of the incident. The internal employers work force were limited to work in certain zones of the store only.The plant room had an exclusion zone and the access road was closed. It was assessed to be unsafe to enter the plant room due to the high concentration of ammonia local to the heat exchangers. A decision was made by the employer and the refrigeration contractor not to call the emergency services (Fire Brigade)



• Conclusion• The ammonia content in the heat

exchanger and vessel above was left to leak to atmosphere before the refrigeration contractor was permitted to continue with the service repair.

• QUESTIONS / ANSWERS


CASE STUDY No 2 • Site Layout (Frozen Food Distribution)- Small distribution outlet, With Ammonia Plant

Room at rear of Building and close to residential area (Refrigerant charge 700kg)

- Direction of leak away from residential area towards well established trees and residential roadWhat Happened:-Operator error reassembling a flanged filter. The engineer opened the supply line to the filter and liquid ammonia filled the room.



• Action / ResponseThe plant room was evacuated and the relevant duty manager notified of the incident. The local emergency services were called (Fire Brigade), who assessed residential area as safeThe service engineer entered the plant room but was unable to gain access to the filter housing due to the dense ammonia cloud. The Fire Brigade attended site and controlled the area until all leakage had stopped



• Conclusion• After initial attempt by the engineer, the

ammonia content was left to leak to atmosphere (with fire brigade in attendance) before the refrigeration contractor was permitted to continue with the service repair.

• Damage to near by Trees • QUESTIONS / ANSWERS


To Stay or Not To StaySUMMARY

• Ammonia Emergency Evacuation Procedures are not optional and must be site specific

• Ammonia Emergency Evacuation –Staff Training for non specialist must be validated

• Ammonia Procedure – Intended for specialist and emergency response staff

• Case Studies:- To stay or not to stay? –Adam Bowey - Grenco Refrigeration Ltd.

ammonia site evacuation

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