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Ammonia as Refrigerant

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The events in Fernie where three people lost their lives due to exposure to high levels of ammonia refrigerant have caught our attention. The facility is for recreation; skating, curling. Ammonia is commonly used in these facilities so the public rightfully asks whether these places are safe. Why is this toxic gas used at all? Is it handled safely?

Technical BC Fernie Incident is a link to the Technical BC analysis of the incident. Their focus is the technical and mechanical details that led to the incident. WorksafeBC will be releasing their report with the focus on worker safety.

Ammonia is used as a refrigerant because it has higher energy efficiency compared to the alternatives, 3-10% better. It is less expensive to install as well. It is rated as a B2 refrigerant, meaning moderately toxic and moderately flammable. Because of this there are codes for mechanical rooms that are designed to prevent the public and workers from being exposed.

In an ice rink, the code essentially establishes a way to maintain two layers of separation between the public and the ammonia refrigerant. Vessels containing the refrigerant are either outside or enclosed in a sealed fire proof room. The refrigerant is not circulated in the floor, but typically a calcium chloride salt brine is circulated in piping under the ice, and through a heat exchanger where the refrigeration system removes the energy. If there is a leak of the brine, there is little hazard. If there is a leak of ammonia, it is either contained and vented in a controlled way from the enclosure, or it leaks into the brine, dissolves in the water and is contained within the brine piping system.

All these safeguards are designed to buy time. An arena full of people would not be exposed to ammonia, and there would be time to safely evacuate everyone in the event of a leak.

The workers who are in the mechanical rooms working on the equipment are required by WorksafeBC to wear protective gear, and each situation being analyzed for the appropriate level of precaution. Up to 35 ppm is safe, annoying but safe. Above that to 300 ppm a respirator and face mask is required. Ammonia dissolves in water, we are mostly made of water, so it dissolves in our tears, sweat, sinuses, etc. At high concentrations above 300 ppm there is not adequate oxygen available and a full self contained breathing apparatus is required.

It is widely used in food preparation in BC. The fruit industry, fish packing and preservation both on shore and on the boats, cold storage, warehouse freezers all use ammonia refrigerant.

The Paris Accord dealing with greenhouse gas emissions encourages industry to move towards refrigerants with a lower greenhouse gas potential. Ammonia has no greenhouse gas potential, along with other natural refrigerants such as hydrocarbons and CO2. Hence we likely will see more ammonia used as refrigerant in the future.

Incidents like Fernie teach us harshly how to work with this stuff safely. The link above to the Technical BC site details how the accident happened. There were a series of decisions made that led to the accident. WorksafeBC and Technical BC is in process of going to all facilities who use this refrigerant to make sure that it is handled safely from the standpoint of the public and the workers. WorksafeBC has a program with four phases; first the ice rink facilities were visited and procedures examined. Then the refrigeration contractors who install and maintain these sites. We have been involved and have developed safe work procedures for all the circumstances we would run into. Then food preparation facilities, then other refrigerant installations will be examined. I will have another blog post on the fourth phase and what that means.

What I got out of the incident report are two things. First the detailed technical descriptions clarified what happened. In my experience this stuff doesn’t just fall apart like that, and indeed it didn’t just fall apart. A series of technical decisions were made that exacerbated the problem. Second, and this is of interest more generally, each decision made the necessary level of knowledge and understanding higher to deal with the next situation that would arise. Let me explain.

First, in 2012 or so, the age of the chiller barrel reached is expected life span. 25 years. The city started the budget allocation process for replacement. The contractor had given them this information, a budget number and from then on it was up to the city to do what it knows how to do; allocate money, find a contractor qualified for the work, and run the project to replace the thing. It was all within the capabilities and skills of the participants.

Then the budget proposal fell off the list for some reason. The necessity of replacing this unit was lost in the many things needing done. The level of understanding required to recognize the priority of replacing this chiller was higher; in fact other consultants missed it. The manager of the facility didn’t know either. It didn’t happen, it wasn’t advanced in the budget process.

Toward the end of the 2016-2017 winter season ammonia was detected in the calcium chloride brine, both by smell and by analysis. This new information required a decision whether to run the plant the next year. During the year prices were acquired for replacement, but the money wasn’t budgeted and the chiller was started for the 2017-2018 winter season. This decision made everything that proceeded afterwards likely and extremely difficult to deal with safely.

In the report there are indications that the severity of the problem wasn’t clear to either the contractor, the city or the plant operators. There wasn’t enough information; how large was the leak, was it going to get worse, how fast would it deteriorate.

Nassim Taleb talks about making decisions under uncertainty. The important information isn’t the details or likelihood, but the consequences. I know that these things can fail slowly or quickly, and it is unpredictable. Precise analysis can be made, but in this situation the thing needed changing. The consequences of the decisions made at this point were catastrophic.

Shortly after startup, the leak got worse. One night the ammonia detector alarmed, the monitoring company called the fire department, they attended the site along with the operator. They had high levels of ammonia in the room, and the surge tanks were banging and vibrating. Let me explain. The water and salt mixture is pumped through the floor and the chiller barrel. It is open at the top, in a surge tank. The ammonia was escaping from the chiller barrel, through the brine piping and out the surge tank. The vibration and banging was indicative of a serious leak.

This situation required a high level of technical knowledge. The fire department is not trained at this level, and cannot be, and the rink operator didn’t have the knowledge either. So the decision was made to isolate the leak by closing valves on the brine system, essentially making it part of the pressure vessel. But the piping wasn’t designed to handle the pressure.

That made a sudden release just a matter of time.

The next step is of personal interest, because this is typically the situation where I show up. When reading the report I asked myself what I would have done in the situation with what I know and could have known. A refrigeration mechanic was dispatched from Calgary, and either didn’t know what he was walking into, or didn’t have the understanding to recognize the situation.

I would guess that of all the refrigeration mechanics in the province who would respond to such a call, maybe 1/4 of them would recognize what the situation was. The situation had developed to a point where a very high level of technical expertise was required to survive. Not only technical; it was unsafe to walk into the room, so getting information from the operator was critical. What do you mean you isolated the leak in the chiller barrel? That is impossible. Then having the wherewithal to recognize and convince everyone that it was a potential catastrophe, and lay out a course of action that would diffuse the situation without loss of life.

But no, the three of them were doing a routine maintenance task when the piping came apart, releasing the ammonia brine mixture and giving them seconds to find a way out of the room while blinded and coughing. They didn’t make it.

Further mistakes and problems with the installation became apparent over the next days.

I suspect I am not the only one who feels angry, disgusted, sad and afraid. We make a living dealing with these and other situations, and plan to retire and get a sun tan on the beach, not at work. There are two conclusions I have come to.

  1. Decisions made early are easy. The situation is not going to get better, so make a decision. It will only get more complicated and expensive. Clear communication with the client as to the situation and potential consequences is necessary.
  2. Uncertainty is the rule. There is no way of knowing what is going to happen. All we know are the negative consequences. In all installations, either ammonia or HFC refrigerants, the consequences of failure are easy to figure out. Those are the important facts upon which to base a decision.
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Written by Kite Refrigeration

July 31, 2018 at 12:33 am

Posted in Uncategorized

Fall Birds

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With the change of weather we are seeing a different population of birds in our area. For a while we saw migrating birds passing through. Now we are seeing the ones that stay around for the winter. Here are some photos that I have taken over the last while.

 

From 2011 Birds
From 2011 Birds

A juvenile male Wood Duck spent a month or so at Kokanee Park while putting on the adult plumage.

From 2011 Birds

I had flushed Wilson’s Snipes at the park a few times, but on this late afternoon where the light was beautiful, this Snipe was quite tolerant of my being near.

From Nelson Waterfront Nov 2011

This song sparrow put on quite the show for me, stretching and contorting itself. I like these photos of small birds hiding in the weeds.

From Nelson Waterfront Nov 2011

This Hooded Merganser was seen on the Nelson waterfront.

From Nelson Waterfront Nov 2011

A Horned Grebe caught some lunch.

Written by Kite Refrigeration

November 18, 2011 at 4:02 am

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R-22

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R-22 and any HCFC blends such as MP-39 or HP80 have seen substantial price increases over the last while. This is due to the phasing out of HCFC refrigerants that started in 2010. Each year there are new surcharges, and the last increase this fall put the price above alternatives.

I will be starting to stock the alternative refrigerants in the new year and will be proposing a changeover strategy for your equipment. The best way is a gradual changeover, taking advantage of repairs to  reclaim the HCFC refrigerant and replace it with an alternative. That would minimize the cost and over time all your equipment will be updated.

The new alternatives promise to be much less troublesome than the R-12/R-502 changeovers from a decade ago. They don’t require changing the lubricants and have good performance characteristics.

Our plan is to select a range of alternatives that cover the three pressure characteristics and use them. There are literally dozens on the market right now.

Written by Kite Refrigeration

November 18, 2011 at 3:48 am

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Enjoying the Kootenays

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The Kootenays are a beautiful place to live. It would be a shame to live here an not enjoy what we have.

I carry a camera with me in the truck and take advantage of the opportunities that present themselves to take some photos. I’d like to share some over the next few months.

I was doing a job in Balfour last winter. It was wet and snowy. This woodpecker was drilling into a snag at the back of my customer’s building. I tried to get some pictures, but he would move around behind the snag. After a few unsuccessful shots I went to do the job. After an hour or so we came out and he was still working away. This time he didn’t hide.

Written by Kite Refrigeration

September 6, 2011 at 1:58 am

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Efficiency and Comfort

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A commercial heating and cooling installation must fill opposing goals; comfort, energy efficiency, reliability, quiet.

A recently completed project had all these goals.

It was imperative that the temperature be comfortable, there be adequate ventilation. The work performed in the space is very detailed and technical, at the same time repetitive. Uncomfortable staff results in mistakes and low productivity.

There was a working system consisting of an old atmospheric gas burner furnaces with air conditioning condensing units. There was an opening for fresh air. The duct work was adequate.

We installed two high efficiency furnaces, each serving a floor. The furnaces have variable speed ECM motors, and two stage gas burners. We haven’t run the system in the winter months, but in the spring it worked well. The heating would run on low fire and low fan, gently warming the space. The occupants hardly knew the system was running.

We installed indoor coils above the furnaces tied to heat pump outdoor units. This gives the owner economic choices when it comes to heating. Currently natural gas is inexpensive, so the heat pump operation is limited to warmup on cool mornings. The cooling is 15 SEER. When the system is running in cooling it isn’t drafty or noisy.

We installed mixing dampers on both systems, along with a relief air hood. They can be run in 100% fresh air mode, or modulated to maintain discharge temperature, or minimum ventilation air. There was an existing Delta control board which we use to fine tune the control. We implemented a free cooling algorithm, where a call for cooling first tries to satisfy demand with fresh air. At the current loads in the space, we disable dx cooling at 19c. We have found that the occupants don’t notice slightly warmer temperatures if the air is fresh.

We also implemented a building purge and cool down cycle. The building has a south-west facing wall with large windows. It gets the sun until it sets in the evening. Previously, the building would continue warming up in the evening, and when everyone showed up in the morning, the outside walls and furnishings were warm. It would take a number of hours running dx cooling to bring the temperature down. The cool down cycle starts after midnight and runs the fan with full open dampers to cool the space down to a degree above heating setpoint. There are a number of logic checks to prevent cooling things down and needing to run the heat to make it comfortable.

The results have been satisfactory. A July hot day, the system shut down at 5PM and went on setback. The building warmed up to 29C. After midnight the fans came on, and by 6am the building was at 22C. The low outside was 16C. The mechanical cooling didn’t come on until around 11AM when building came out of the shade of it’s neighbor and started warming up. The current draw for the various components makes 1 hour of dx cooling equivalent to 7 hours of fan at full speed. In the hottest conditions we cut the equivalent of 2 hours of dx runtime, or approximately 20%.

We and the client are quite satisfied.

If you would like us to sort out a similar problem, please contact us.

Derek Kite

250-352-0199

Written by Kite Refrigeration

July 11, 2011 at 12:14 am

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Kite Refrigeration

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We provide refrigeration and air conditioning services in the Trail, Castlegar, Nelson and Kaslo B.C. area.

Air conditioning service and installation. We install conventional hardware and the LG line of single and multi zone splits.

Controls. We service many different brands of refrigeration and building DDC controls.

Refrigeration. We service install anything from grocery store racks to small commercial refrigeration and freezers.

Heat pumps. We service and install air source heat pumps for residential and commercial applications.

We work on environment boxes used for industrial testing.

Contact us at 250-352-0199

Email derekkite@kiterefrigeration.com

Written by Kite Refrigeration

May 15, 2011 at 1:25 am

Posted in Uncategorized