Problem Solving Article: Industrial space heater fire 

An Article from the Series of Problem Solving Articles in an Industrial Setting

Fall was at hand and all the large, industrial space heaters in the cannery plant needed to be tested. There was one heater mounted on the wall in the maintenance shop area. The space heaters were needed for worker comfort and to control humidity in the warehouse.

The heater was thermostat controlled with a 480 VAC motor. The controls were 120 VAC. The thermostat used 12 VAC through a transformer.

The thermostat turned the heater on. The gas was ingited by a pilot light and then the fan motor came on when the heat in the firebox reached the setpoint.

The fan pulled in air from the surrounding plant and then blew it around the gas-heated pipes of the firebox and out into the plant. The burned gas exhausted out a pipe that exited through the roof.

The gas shutoff valve and gas pressure reducer for the heater were located adjacent to and a little above the main frame of the heater. The gas pipe was 1/2" black pipe but used an aluminum, flexible tubing from the pipe to valve on the reducer. The reducer vented to the surrounding atmosphere in the plant and warehouse.

Apparently, the space heaters had not been cleaned for a number of years. The air in the cannery was open to the warehouse. The air in the cannery contained olive oil in a mist.

The olive oil had collected on the space heaters and then dust had become trapped in the olive oil film. This process had been going on for years.

I had misgivings about turning on the heater in the shop area and they were well founded, as it turned out. There were five fire extinguishers in the shop.

The heater was turned on at the thermostat. After a time, the blower motor for the fan came on and shortly, smoke started coming out of the blower opening. Then smoke startd coming from the back of the heater.

I told the electrician to shut off the 480 VAC power to the motor. I thought that was where the smoke was originating. I was wrong.

Flames appeared at the back of the heater. I grabbed an extension ladder and set it against the wall and pulled it up to reach the heater.

The flames grew higher and started coming out the front of the heater. I grabbed an extinguisher and climbed up the ladder. I shot the extinguisher on the flames and they died down a little.

I passed the empty extinguisher down to the electrician and he passed up a full one. We were using CO2 extinguishers. Initially, I did not want to use the ABC powder extinguishers due to the large amounts of powder particles they put into the air.

Another electrician came into the shop and I told him to turn off the 120 VAC power to the gas valve and thermostat. He searched through the elctrical panel in the shop but without success.

I had gone through five CO2 extinguishers and was using an ABC powder extinguisher. I shouted at the electrician to shut off the main power to the panel. He did.

I was finally able to reach the gas valve and turned it off while receiving first and second degree burns on my hands and arms. The oil film on the heater was still burning as well as the motor and even the paint. 

I was afraid that the heat would somehow melt the gas tubing and then we would have had to shut down the main gas into the plant. We might have lost the whole plant if the fire got away from us.

I was hot, tired, burned and worried. I grabbed one more extinguisher and told the electrician that if I couldn't get it out to call 911.

I had been a volunteer fireman for 7 1/2 years in Dhahran, Saudi Arabia, while employed with the Saud Arabian Oil Company. Had it not been for that valuable and extensive training and live experience dealing with fires, I would have called the fire department much earlier.

The plant would probably have been lost along with the jobs of 300 employees, including mine. The plant was old with lots of old wood and then, of course, there was the olive oil and olives. The fire would have been extremely difficult to fight and extinguish.

With the seventh extinguisher, we finally succeeded in extinguishing the flames. I was satisfied that we had saved the plant and put out the fire.

I directed the maintenance crew to clean up the area. I was acting Plant Engineer and Maintenance Department Supervisor and needed to write up a report on what had just occurred.

Sweat was streaming down my face and mixing with the oil, grime and soot from the fire. I was a mess to look at. My hands and arms stung from the sweat on the burns. I was still pumped with adrenaline from the fire.

The Vice President was running the company as the President had resigned to take a more lucrative position. I went up to his room and entered his office. He looked at me and asked me what had happened. I told him. He said good work.

When I finally realized that was it, I went to my own office and prepared the report on the fire and sent copies via email to all the remaining management in the company.

Cold water was used to reduce the effect of the burns on my hands, arms and face. I have also had first aid and Emergency Medical Technician One training and certification.

The next day, I prepared and implemented a plan to pull every one of the 16 large space heaters, bring them to the shop, remove and overhaul the electric motors, replace bearings and belts, steam clean the housings, reassemble the heater, and then test run each heater in the maintenance shop before reinstallation.

Had the fire occurred on one of the heaters in an inaccessible area, there would have been no stopping it. 

A field technician from Pacific Gas and Electric Company stopped by my office that same day. He told me that he was checking our large gas reducer for all the plant except for the gas supply to the three steam boilers.

He wanted me to accompany him while he checked out our in-plant gas system. The main load for the in-plant system was the gas fired space heaters.

The first one he checked had a problem. He said that the gas reducer for the heater must be vented through the roof. That would mean running a 1/2" pipe from the heater up and through a hole in the roof. 

The pipe would have to be routed from the reducer to a roof support so it could be clamped to reduce or eliminate movement of the pipe. The hole through the roof would have to be sealed around the pipe to prevent water from seeping into the hole. 

The pipe would need to extend about one foot up and then have two elbows attached so the opening pointed down to prevent the entry of rain. The end of the pipe had to have a special, screened fitting to prevent the entry of bugs but allow the pipe to vent the reducer.

I ordered the parts and contacted our General Contractor, Tony, to look over the job. He would be able to pull two men from the work they were on to do the vent job. Some of the vents on the heaters would be done at the same time as the space heaters were pulled for overhaul.

The overhaul was being carried out by the plant maintenance mechanics and electricians. It was a big job and I was going to have the G.C. and his crew assist them when necessary.

All the work was completed on time. We had excellent work crews, bot in-plant and contractors. The heaters would come on and light up when called to do so by the thermostats and begin heating the air. Without catching on fire.

Feel free to copy this article in it's entirety as long as you include the credits below. Thank you for spreading the knowledge.

Author: Larry Bush 
Profile: Electrician in industrial, construction, marine, and food industries for 47 years, with 22 of those years in management.
URL: http://www.reliability-consultant.com