......Perhaps not every poorly executed procedure will ultimately result in death or injury. However, many cases have been documented in which fatalities occured. As mentioned in the toxicology lesson, anoxia (lack of oxygen) is the primary hazard associated with confined space entry. If proper precautions aren't taken to ensure a safe atmosphere death can result. Study the following cases as examples.
CASE No. 1: Sanitary Sewer
A laborer entered a 20 foot deep sanitary sewer to remove debris that was blocking the flow of high pressure flushing water. A short time later, a
second worker observed the laborer unconscious at the bottom of the manhole. He too entered and was overcome.
A third employee, suspecting a problem when he saw the second man enter, ran over and found both workers collapsed at the bottom. He too entered but must have realized that he made a mistake, because he was later seen trying to crawl out the top. Unfortunately, just as another on-looker ran to help him over the edge of the manhole, he fell too fell the bottom.
The Fire Department eventually arrived and extracted the three bodies. However, the rescue was not without further incident. A Fire Captain involved in the extrication was almost overcome because he was not wearing a self contained breathing apparatus.
Atmospheric tests conducted about an hour after the accident showed 1 - 2% oxygen and 120,000 parts per million
(ppm) carbon dioxide.
CASE No. 2 Rendering Plant
An employee entered the basement of a rendering plant to unplug a six inch drain line leading from the scale pit to the basement. This line carried water and juices of animal material that collected under the scale pit to the
basement to be pumped via a sump pump to a vat for processing. When the pipe was unclogged he returned to the main floor.
When the skimmer trap leading to the vat was full, the employee reentered the basement to block the sump pump float in the down position thereby stop-
ping its operation. He then started to limb the stairs out of the basement pit and was observed falling backwards by the plant manager. The manager instructed two other employee to enter the basement and rescue the injured worker while he called an ambulance. On the way the manager saw another worker and instructed him to assist the others.
The rescue squad arrived shortly, however, while attempting to rescue the employees, two responding fire fighters were overcome. The fire fighters
eventually recovered. The four employees did not.
CASE No. 3: Rail Tank Car
One August day a crew of four employees was assigned the task of removing an inert powder from a tank car. The job began in the early morning and by the time of the first break it had become pretty hot and humid inside the
car. One of the employees thought it would be a good idea to ventilate the car while they were on break. He coupled up a length of hose to the plant air system, tossed it down the man-way and went off for a cup of coffee.
Unknown to the work crew, certain plant processes had to be maintained at constant pneumatic pressure. To assure this, a back up system of compressed nitrogen cylinders was connected to the plant air line through a solenoid
valve. In the event of compressor failure, the solenoid opened allowing the nitrogen to flow into the line. What the employees didn't know, was that day, the compressor was being over hauled.
The crew returned from their break and prepared to resume work. As soon as the first worker's head cleared the man-way he collapsed and fell to the
bottom of the car. A second employee, seeing that the first was in trouble, also entered and collapsed with his head falling on the first victims chest. The third employee, thinking victim number two was checking for vital signs,
also entered and collapsed. The fourth employee, seeing the pile of unresponsive bodies on the bottom of the car suspected an air contaminant. He ran to get a gas mask.
As he returned to the car, he was stopped by the plant nurse who asked what was going on. When he explained the nurse instructed him to use an SCBA rather than a gas mask. He put on an SCBA but was startled to discover that
he couldn't fit through the narrow man-way with the tank on his back. While keeping the face-piece on, he removed the tank so it could be passed down to
him once he entered the car.
Not being trained in the use of the SCBA, he had opened the emergency bypass valve rather than the control valve. The continuous flow of high pressure air coupled with a poor face-piece seal caused the air to be quickly expended while he was inside the car. He too was overcome.
By the time the fire department arrived the workers had been in the car for about 15 to 20 minutes. Fortunately, no one died. A four inch bottom outlet valve had been left open, and by coincidence, all of the victims fell in the vicinity of the valve opening. Apparently, there was enough outside air diffusing in that no one was permanently injured.
Continue the discussion of confined space hazards by learning about the Domino effect....Press the button to the
left.
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THE DOMINO EFFECT-
Although confined space accidents don't happen often, when they do they're usually fatal.....and often they involve multiple fatalities. Usually, an innocent bystander, coworker, or even a trained rescue worker will enter a confined space attempting to rescue the first victim. The rescuer himself untrained in the hazards of confined spaces will fall victim. This aspect of multiple fatalities is like a chain of dominos. Many instances of one, two, three....even five victims have resulted from rescue attempts.
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