Mark Conley
Active member
If there was one fun thing about being a BEE Technician, it was that lovely check for explosive emissions test we did all the time.
A check for an explosive atmosphere test, or Lower explosive limit (LEL) was part of the series of tests that had to be determined by the base Hospital Bioenvironmental Engineering personnel. These test, involving an explosive-meter of some sort, compared the ratio of some non-inert gas and oxygen to the level it would take to explode and cause death and mayhem. Why the fire department didn’t do this, I will never know.
All my checks were performed using an old Davis vapo-tester, which required you to pump quite a lot of air over an old fashioned Wheatstone filament before you got an adequate reading. As the workplace’s lowest ranking airman, I was always designated to perform these checks.
Now notice I said explosive atmosphere testing. You could have a flammable amount of material present, with out it exploding. All it would take would be a source of ignition to set it on fire, and you would really have a problem that wasn’t determinable by the LEL. This was something you had to explain carefully to people, as they took every LEL reading of nothing or Zero to mean it was a safe condition.
Stage Set? On with the tale
One morning I was directed to the base fuel yard, to support the civil engineering unit in assuring the workers in today’s trench that there was nothing wrong. I was directed to a trench, which I measured for oxygen content and explosiveness. Everything was 21 % oxygen and LEL below zero: a sign that everything was go in the trench for work. One of the items scheduled for those days’ festivities was welding a flange to a 6-inch pipe end for hook-up to a new series of tanks. This was to be accomplished by arc welding.
Well the welder (he was a civilian, by the way) laid mats in the bottom of the trench to catch the sparks, dropped his hood, and started welding like there was no tomorrow. I decided to stay behind and monitor, for no other reason other to get out of work at the office, and to watch a master at work.
Lets get back to that little thing called flammable.
A few hours into the work, some sparks jumped on to the wall of the trench…and finally found some flammable JP-4. Good ole Jet Petroleum Compound four. A mixture of kerosene and benzene so lively, it would catch fire at less than a hundred degrees ignition temperature. No matter what amount you had, if you had sufficient oxygen and an ignition source hotter than a hundred degrees, this fuel would catch on fire. No Boom. No Explosion. Just Fire.
Suffice to say that this fuel yard was almost 45 years old. Over that period of time, enough fuel had saturated the soil from leakage, and spillage to be quite the problem if it ever had a source of ignition to ignite it. Say like steel arc welding spatter at 1100 degrees Fahrenheit. Which that man was producing in a serious amount in that trench.
Well it happened. While the man was busy at his pipe, some earth caught fire at the edge of a mat and proceeded to fill one end of the trench with flames quickly. Now I was essentially daydreaming in the trench, justifying my existence by taking LEL measurements every 15 minutes or so; suddenly I was awoken from my happy place by the sudden application of heat. Lots of heat I saw that about five feet of the trench was in flames…and starting to get longer.
Yelling like a idiot, I grabbed my coat and started beating out the flames: coming out his revelry, the welder grabbed a fire extinguisher on the other side of him and preceded to fight the flames as well. For about 5-8 seconds, we fought that little private fire until it was out; all I can say was we were lucky fools.
After the fire was out, the welder looked at me and said, “I thought you said it was safe, that there would be no explosion”. I gave him my best knowledgeable look and said” Well did you almost die in an explosion back there?” He had to agree that he hadn’t, but explosive, flammable, or smelly, he wasn’t getting back into the trench to do anymore welding until it was safe to do so.
They finally had to come in and saturate the ground with some material from the fire department that kept the fuel from getting oxygen or something. The man wouldn’t go back into the trench unless someone was in the trench and monitoring him the remaining time it took to finish the job.
It was a restful, if slightly suspenseful three days off I had….
A check for an explosive atmosphere test, or Lower explosive limit (LEL) was part of the series of tests that had to be determined by the base Hospital Bioenvironmental Engineering personnel. These test, involving an explosive-meter of some sort, compared the ratio of some non-inert gas and oxygen to the level it would take to explode and cause death and mayhem. Why the fire department didn’t do this, I will never know.
All my checks were performed using an old Davis vapo-tester, which required you to pump quite a lot of air over an old fashioned Wheatstone filament before you got an adequate reading. As the workplace’s lowest ranking airman, I was always designated to perform these checks.
Now notice I said explosive atmosphere testing. You could have a flammable amount of material present, with out it exploding. All it would take would be a source of ignition to set it on fire, and you would really have a problem that wasn’t determinable by the LEL. This was something you had to explain carefully to people, as they took every LEL reading of nothing or Zero to mean it was a safe condition.
Stage Set? On with the tale
One morning I was directed to the base fuel yard, to support the civil engineering unit in assuring the workers in today’s trench that there was nothing wrong. I was directed to a trench, which I measured for oxygen content and explosiveness. Everything was 21 % oxygen and LEL below zero: a sign that everything was go in the trench for work. One of the items scheduled for those days’ festivities was welding a flange to a 6-inch pipe end for hook-up to a new series of tanks. This was to be accomplished by arc welding.
Well the welder (he was a civilian, by the way) laid mats in the bottom of the trench to catch the sparks, dropped his hood, and started welding like there was no tomorrow. I decided to stay behind and monitor, for no other reason other to get out of work at the office, and to watch a master at work.
Lets get back to that little thing called flammable.
A few hours into the work, some sparks jumped on to the wall of the trench…and finally found some flammable JP-4. Good ole Jet Petroleum Compound four. A mixture of kerosene and benzene so lively, it would catch fire at less than a hundred degrees ignition temperature. No matter what amount you had, if you had sufficient oxygen and an ignition source hotter than a hundred degrees, this fuel would catch on fire. No Boom. No Explosion. Just Fire.
Suffice to say that this fuel yard was almost 45 years old. Over that period of time, enough fuel had saturated the soil from leakage, and spillage to be quite the problem if it ever had a source of ignition to ignite it. Say like steel arc welding spatter at 1100 degrees Fahrenheit. Which that man was producing in a serious amount in that trench.
Well it happened. While the man was busy at his pipe, some earth caught fire at the edge of a mat and proceeded to fill one end of the trench with flames quickly. Now I was essentially daydreaming in the trench, justifying my existence by taking LEL measurements every 15 minutes or so; suddenly I was awoken from my happy place by the sudden application of heat. Lots of heat I saw that about five feet of the trench was in flames…and starting to get longer.
Yelling like a idiot, I grabbed my coat and started beating out the flames: coming out his revelry, the welder grabbed a fire extinguisher on the other side of him and preceded to fight the flames as well. For about 5-8 seconds, we fought that little private fire until it was out; all I can say was we were lucky fools.
After the fire was out, the welder looked at me and said, “I thought you said it was safe, that there would be no explosion”. I gave him my best knowledgeable look and said” Well did you almost die in an explosion back there?” He had to agree that he hadn’t, but explosive, flammable, or smelly, he wasn’t getting back into the trench to do anymore welding until it was safe to do so.
They finally had to come in and saturate the ground with some material from the fire department that kept the fuel from getting oxygen or something. The man wouldn’t go back into the trench unless someone was in the trench and monitoring him the remaining time it took to finish the job.
It was a restful, if slightly suspenseful three days off I had….
