"Plan B" when electronics fail
Volume 24, No. 4
Electronic devices and controls are much like tungsten light bulbs, they either work or they don't, period. There is no such thing as a roadside fix for these devices. I typically focus on chemical hazards, but it is equally critical to prepare for hazards associated with potential electronic failure of our emergency response and detection resources.
To embrace electronics and electronically controlled equipment we responders must perforce be prepared to cope with the failure of electronic components. There must be a Plan B.
The first and perhaps most essential component of Plan B is routine or scheduled preventive maintenance. The automotive battery is a marvelous creation. It sits in a little box under the floor or on the side of the vehicle and often gets little or no attention during its entire life. Amazingly enough, these batteries usually work very well for extended periods of time, often for years, but when they do go out their failure is often instantaneous. Many emergency response vehicles are equipped with dual batteries and in some cases dual alternators. Batteries, particularly those found in portable equipment, have a shelf life and when they get close to the end of this useful lifespan, they should be replaced. This applies to vehicle batteries as well as to those found in instrumentation and other pieces of equipment. The work should be done by someone who is knowledgeable with regard to the equipment and it should be carried out at scheduled intervals in an unhurried manner on the apparatus floor, with proper tools and equipment rather than with a dull pocket knife on the scene of a four-alarm barn burner at three in the morning.
Even today, not all equipment utilizes rechargeable batteries. The old fashioned "dry cell" or "D" cell is still in use. These have a definite life span and common sense alone dictates that a reserve supply of these cells should be on hand for any emergency. It simply is not considered good bull to find oneself having to rob the batteries out of flashlights in order to replace the exhausted cells in an Explosimeter. "C", "AA" and "AAA" cells are common also as well as the various "button" mercury cells found in cameras and other equipment. Now, our hand full of "D" cells has grown to the point where a battery supply box with enough different types and sizes to stock a small store is a "must have" item at every response.
Sensors too have a definite shelf life and this is a factor that can be greatly affected by the local environment. Often the ultimate cause of failure in these devices is drying of the electrolyte or other chemical solution they contain. The productive life of one of these sensors will, therefore, be considerably longer in Seattle than it will in Phoenix, and the prevailing climatic conditions must definitely be taken into account when establishing replacement intervals.
Other types of sensors also have their limitations. The old MSA Explosimeter, for example, was not intended for use with automotive gasoline vapors because the lead in the gasoline in use at the time would quickly poison the platinum filament that is the sensor in this instrument. Again the question presents itself: Where can people get a replacement sensor and how long will it take to get here? Has someone already borrowed the spare that is located inside the instrument case for such an emergency and failed to replace it? What is the shelf life of an unopened sensor? Can a replacement be stocked or do people rely on the dealer or manufacturer?
Storage conditions also must be considered with regard to sensors that contain electrolyte solutions. In climates susceptible to freezing, these must be protected from cold weather. Freezing can cause the electrolyte to expand and this may damage the body of the sensor rendering it inoperative; it may also "denature" the electrolyte itself. Freezing happens sometimes without the user's knowledge. A responder picking up a meter on a warm spring day in May has no way of knowing that the instrument froze last January -- at least not until he tries to turn it on.
In cases where instruments and other electronic devices are left in unattended storage for extended periods it is highly recommended that an indicator shows that the equipment has been subjected to sub-freezing temperatures. This does not need to be elaborate; a common max/min thermometer of the type utilized in green houses will do the trick. Another approach is to get an electronic weather thermometer (about $10 at Wal-Mart) that shows the highest and lowest temperatures to which the probe was subjected. One of these inexpensive instruments can be placed on the outside of the building with the probe inserted into the interior through a small hole. When the low temp button is pressed, the unit will show the lowest temperature since the last time the unit was cleared. In use each time the facility is entered the lowest reading is checked and the thermometer reset. This way the low reading will always be the lowest temperature recorded since the last entry into the facility. These instruments also indicate the highest temperature occurring since the instrument was cleared. This too is important since many sensors and other instrument components are sensitive to high temperatures as well as to low. Of course this instrument also is electronic in nature. Therefore it will have a battery that need periodic replacement.
Rechargeable batteries gradually lose their charge when not in use and should be refreshed frequently. These, particularly NiCad=s, will, over time, develop a memory and fail to deliver their full capacity rather than discharge beyond the memory point. To prevent this, many manufacturers have introduced cycling re-chargers. This equipment periodically depletes the entire charge from a battery and recharges it. The use of equipment of this type is highly recommended.
Another point that should be considered at the time a piece of equipment or apparatus is purchased is: what happens in the event of "black box" failure? Does the equipment give a timely warning of imminent failure? Does it "fail safe?" Does it fail in a way that does not jeopardize the rest of the operation? The car my pastor drives comes to mind. I appreciated knowing that one of the tires is over inflated (though it would have been nice if we could have been told which one) but shutting down the engine to twenty miles an hour during rush hour on a freeway with a speed limit of seventy-five cannot genuinely be called "fail safe." A simple warning to check tire pressures would have allowed us to reach the nearest service station or find a place we could pull over and address the problem. In other words to "make an orderly shutdown." Had this been an emergency call, the result could have been far more serious. The obvious answer would be to design the tire pressure monitoring system in such a way to acknowledge the problem. A half pound difference in tire pressure simply does not justify shutting down the whole vehicle in the middle of a busy freeway - particularly when it is a matter of too much pressure rather than too little.
SCBAs are not exempt from this issue. In order to provide enough pure air to enable a responder to leave an unsafe area in the event of such a happening, the units were originally equipped with a bypass valve which would enable the wearer to flush out contaminated air from the face piece or, in case of a regulator malfunction, inject air manually until he could reach safety. These units were often stored on "ready racks" or on apparatus for long periods of time between being used. About all that was needed to be checked was the pressure in the cylinder and occasionally a check to see that the regulator would operate as intended. At the last IFW conference in Beaumont, a new and improved SCBA infused with computer and electronic sensors and monitors. Now the question presents itself: How much more inspection and maintenance will these new units require and how often will it have to be done? If there are electronics involved, there has to be a battery somewhere; will connections on the "ready rack" keep the batteries charged? What happens if a battery goes down? Just how will these units "fail safe?" Will these new and improved units with their sophisticated electronic triggerwork be as robust as the older units? Anything strapped to the back of an active firefighter had better be robust; will it "conk out" the first time it is dropped or if the user suffers a fall inside a burning building? Before converting to these electronic marvels, someone had better ask some questions.
?Of course the most important factor in an instance of electronic malfunction or failure is the speed with which the nonfunctional equipment can be returned to service. The immediate availability of spare or replacement parts is, of course, vital and, in the case of emergency response equipment, essential. Does the dealer stock replacement parts locally or do they have to come all the way across the country or even from overseas? More importantly, what do people do in the meantime? Continue to operate in an "override" mode? The time to find out is now, not when the failure occurs.
Have equipment operators and others been trained in the implementation of "Plan B" in the event of a failure? Can they operate the equipment in the "old fashioned" mode? If not, a training session is in order. In fact simulate an electronic failure during training exercises from time to time just to make sure that those whose welfare may well depend on the proper functioning of their equipment are able to "cope" when it fails. This is Plan B. It may be "quick, cheap and dirty" but it may save property and possibly a life.