There is no such thing as an Accident in the workplace.

An accident is typically deemed an unfortunate or unplanned event without deliberation that leads to a near miss, injury or fatality. This suggests that a degree of chance or misfortune was involved.

On October the 5th of 2004, 1218 pm, I was undertaking a routine task; something i had completed a thousand times before, draining oil from an Ammonia refrigeration pressure vessel. The result of what occurred that day changed my perception of safety in an instant; the importance of hazard management. There is no such thing as an freak accident, every incident has a series of preventable events or actions that lead & follow a near miss, injury or accumulated illness. For the last 13 years I have researched & developed training methods to educate both technicians & end users on the importance of safe work practices regarding Anhydrous Ammonia.

"Unfortunately it must have been difficult for the staff to take a half-naked man dripping wet and in shock too seriously and they went about their business."

My story

Admittedly the following details are difficult to share with the world as they point out my failures as a professional, it is something that i usually save for my presentations as a ice breaker, particularly when pointing out the areas where i received the most cryogenic and corrosive burns to my body. But in-light of a recent discussion, as well as last weeks horrendous fatality count in New Zealand workplaces, I think its important to share my experience and complacency with others. It not only highlights unsafe acts but it indicates the need for continuous identification and enforcement of risk controls in the workplace. The gritty details of incidents are rarely shared therefore we never learn from them.

I was sent to a job to perform a maintenance on a relativity large two stage Ammonia cold-storage facility. The week prior i prepared the oil rectification vessel for draining oil. So this week was drain week and then filling for it next cycle. My preparations for the task were somewhat minimal i might add, no JSA (What the hell was that) just a spanner in my pocket and my respiratory protection which i hung over a compressor lifting eye some 3-4 metres distance. On opening the drain valve unbeknown to me, I snapped its shaft, after the oil was drained an Ammonia oil mixture began to appear. The valve was then front seated however the Ammonia continued to flow

At this stage I had turned this valve shut twice over and realised something was terribly wrong. In an attempt to direct the Ammonia stream and splashes away from my body, I found that the industry standard 'rubber hose' connected to the valve by a hose clamp had frozen solid. Ammonia liquid was now splashing all over my body and the vapour was forming corrosive Ammonium Hydroxide on all of my moist tissue.

Knowing there was three ton (3000 kg) of Ammonia directly connected to this oil rectifier vessel and a primary school less than 200 metres away, I remember thinking "Even if i die in the process, I must isolate this system."

Rapidly, the entire plant room was thick with an Ammonia aerosol and I was forced to hold my breath and close my eyes. The Ammonia blanket i was now wearing was immensely cold and i could feel its weight on my face and body. I was unable to locate my respirator that should of already been on my face.

The vapour return valve (That should of been shut) had a rubber gland packing, it was dry and therefore incredibly tight, it seemed like it took forever to isolate the circuit. Finally i front seated the valve and the remaining content of the vessel was left to vent slowly reducing in pressure as it was released.

On exiting the plant room blind and breathless, to add heat to the already dire situation, I managed to stand on a garden rake which smacked me square in the face. I Bruce Lee kicked the plant room door open and went directly to the emergency shower and pulled the chain. However in the unthinkable occurrence someone had isolated the water supply, as i later found out due to it leaking.

The ball valve was just out of reach as well as had the handle removed, my hand tools were stuck inside the plant-room together with my keys to the back of my vehicle. By damaging my Ute, I was able to get a spare spanner and box to stand on and open the valve. The cold water hitting my burns was excruciating and put me into further shock. I had removed most of my clothes and stood there shaking and with a hose down my pants as the shower does nothing to accommodate groin injuries. Workers just watched, no one came to my aid or offered assistance.

After gathering my composure... a little, I checked the plant room, it was still full of Aerosol and very“HOT”. I realised the plant room ammonia alarm was in bypass for maintenance which meant the fans did not force on and neither did the evacuation alarm. There were no controls outside, and there was no shunt trip to stop the plant from igniting the ammonia.

I hustled to the office to advise the staff to call the Fire Service as well as evacuate the site. Unfortunately it must have been difficult for the staff to take a half-naked man dripping wet and in shock too seriously and they went about their business.

Furious of the stupidity of the situation, I jumped in my Ute and drove to the closest A&E which had no clue on how to treat me and sent me to the next hospital, they still were also unaware of what to do. After waiting for what seemed an eternity, I demanded a Luke warm Shower, I was given petroleum jelly to apply to burns the ordeal was over. 

Now, your all thinking what an idiot! Yes I agree. This brings me to my point, none of these series of events should of taken place including my own cockiness.

The events

1. Although I was holding a Refrigeration Qualification and been working on Ammonia systems for 10 years, I was never formally trained in the procedure because there was none. I was trained by someone who had 40 years experience but knowing what i know now, even he was doing it wrong. By double isolating the vessel using the vapour return valve, even if the worst occurred, i would of been able to walk (Swiftly) away knowing only minimal Ammonia would be released.
2. Lone working is something that should never happen when conducting hazardous operations. A second person may of noted my lapse in procedures or been able to perform other duties including notification of release, first aid, or rescue. My superiors also had no idea where i was. Imagine how that phone call to my family would of went down.
3. Still to this day, I come across service procedures that include statements like, "Ammonia mask should be available" If an Ammonia Hazard exists, the personnel protection should be worn, full stop.
4. Many works on Ammonia systems create a localised high concentration pocket often exceeding IDLH values. In the case of Ammonia this is just 300 ppm. Personal gas detection must form an integral part of respirator use to identify the correct selection of equipment as well as its limitations. Self Contained Breathing Apparatus should be utilised in many occasions of service work for this reason.
5. The design of Ammonia systems has suggested the installation of Quick close drain valves (QCDV) or "Dead-man valves" for many years prior but for some reason; im guessing financial they were not installed on almost all plant we worked on. This would of prevented the incident all together by way of double isolation. Upon my recovery, i went about installing them everywhere often without consultation with the owners. They had to have them or we wouldn't be draining oil. I keep a spare ball valve in my tool box when ever i need to test a service point that does not have a double isolation. This includes transferring ammonia or oil.
6. Flexible hose should never be used for draining oil, not only is it not designed for the low temperatures but when an unfixed line is incorporated into the process it can snake under the hammer of Ammonia expansion. Any fixed line should be directed away from the body and away from the path of escape. It should not be reduced in size as this increases the velocity of oil/ammonia exiting the line.
7. Gas detection service bypass. Where installed the service bypass on most plants impairs the entire alarm rationale. An lower explosion level (LEL) sensor must be installed and operate independent of the service bypass. An LEL also allows to increase the shunt trip set point as toxicity sensors alone shunt early which can increase the pressure of a leak source, effectively making it worse. Many instances of leaks, the plant is needed to operate so that the management of pressure can occur i.e using the compressors to reduce the pressure and evacuate the Ammonia. Restart after a shunt can destabilise the entire plant and delay the restart. An LEL can remain on and visible to emergency responders where a toxicity sensor can not.
8. Emergency ventilation should be automated to start by the Fixed gas detection set point, this should be capable of limiting the concentration within the plant-room and just as importantly exhaust of the contaminants must not be allowed to recirculate or vent to ingress or egress doorways.
9. Emergency shutdown, Luckily that day either the concentration mixture was not in range to ignite or by chance it did not. Shunt or remote trip from the gas detection should of remove all potential for ignition and a manual emergency stop should be available inside and outside of the plant-room.
10. What did they use to say? "House keeping is the first rule of safety" yeah so why on earth were garden tools all over the floor of a fridge plant? And why on earth did i not ensure my escape path was clear?
11. Cold water is not an effective method of decontamination, but more importantly no water at all is even worse! Showers should be tested ritualistically prior to Ammonia service works and regularly "bumped" by the facility to ensure the water supply is actually online and the flow is sufficient for decontamination. Luke warm water opens the pores of the skin to flush chemicals. Cold water closes the pores reducing the decontamination effectiveness.
12. Awareness & training is lacking by many facilities, but ignoring emergency action is mind-blowingly idiotic. Engaging all responders and personnel in the process of emergency management is vital. This does not mean all facilities must have a rescue squad but it does mean there must be a chain of command to deal with the situation appropriately. In this situation activating the plan by communicating with the right person or manual call point. In hind sight activating the fire alarm would of been sufficient to evacuate the workforce.
13. Another lucky occurrence that day was the as the ventilation was not operating it did not exhaust Ammonia all over the show and was allowed to slowly dissipate via the duct. If it did there may have been a problem evacuating. In the case of this facility it did not vent upwards however it did vent just metres of the office entry point. Of course there was no wind indication so knowing which way to evacuate or shelter would have been a problem.
14. The last event in my ordeal was what made my jaw drop the most, there was no available information for nurses or doctors to know what to do with me. Just as bad, sending someone away to drive themselves to the next hospital in shock is downright negligent. Knowing what actions to treat someone who has been involved in a chemical accident is priceless.

I have undoubtedly learnt the hard-way, but as such have spent many a night studying and developing ever evolving works to combat the above and more deficiencies in refrigeration design, installation, operation and emergency recovery. I have since established Gauge refrigeration Management Ltd to assist companies with there concerns with Ammonia hazards in the workplace. Our focus along with a list of collaborated businesses is training end users and technicians alike on both sides of the bow-tie. Prevention and preparedness. Removing the stigma and educating the benefits of its efficiency and natural occurrence in nature but at the same time educating of the risks through surveys and hazardous operability studies. If you believe your business could use help with identifying your Ammonia risk potential or developing procedures for recovery, please do not hesitate to contact us at Gauge. [email protected]

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