ASK ERNIE - The Apparatus Maintenance Expert


CarolinaFireJournal - Anthony D. (Tony) Bulygo
Anthony D. (Tony) Bulygo
07/15/2014 -

What are some common air leaks that occur on fire apparatus?
First off, let’s discuss a little about why we have a leak. Many of the issue of air leaks can be traced back to poor or lack of air system maintenance which includes; Air compressor inlet filter replacement or an inlet hose that is inspected for restrictions; debris, oil, or water in the air tanks — usually caused by a lack of knowledge of how to recognize when the air dryer function is depleted. Contamination of the air supply is contamination of the entire system and results in failures and leaks.

Now, on to common leaks: Foot valve, cab control valve (that diamond shaped yellow valve handle on modern fire apparatus), air horn valve, relay valve(s), air hoses and supply lines throughout the chassis, air chamber diaphragms (both service and parking brake sides), air suspension components, air horn relay of manual valves, air raised scene lights, air seats, air fittings, and if your unit is old enough, you might even have air assisted steering or air wipers. If it is air operated, it can leak. An excellent ally in discovering air leaks is the use of electronic ears.

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In the fire service industry what are the cab test requirements?
While NFPA 1901 covers vehicle stability quite extensively, it does not mandate crash worthiness for both the custom and commercial lines. However, due primarily to competition, all major fire apparatus custom chassis manufacturers have adopted to meet or exceed all NFPA, SAE, and ECE 29 (Economic Commission for Europe) crash specifications whereby the cab of the commercial units must remain intact during severe frontal, side and roof impacts. Check any major custom fire apparatus chassis manufacturer for their testing standards.

Is there new apparatus technology coming in service?
Consider that most new changes will be centered on electronics. Like, brake by wire. Yes, it is in testing. Easy, there, aircraft have had brake by wire for decades. How about crash avoidance with associated braking for an example? And if you have not purchased apparatus lately, you now have VDR (Vehicle Data Recorder) on board all new apparatus since 2009. Don’t think of this as big brother watching your every move, think about it as a legal backup to support your statements following an accident. “Witnesses” will make many statements that usually cannot be backed up. Your statements, with the help of the VDR will back you up 100 percent if you do things correctly and operate safely.

Why is it important to have a third party testing service performing pump testing?
Uncle Ern is a little confused by the question. Are you referring to the pump manufacturing certification, the apparatus manufacturer pump test certification, or the annual in-service pump testing? The pump manufacturer builds and then tests each pump to perform beyond the stated capacities. The fire apparatus builder wants extra finger prints on the final product, viewed and certified by an independent third party to verify the claims of the apparatus manufacturer. The apparatus manufacturer testing is open to additional eyes-on testing by the purchaser. If you refer to the annual pump testing by the end user, it does not need an independent third party to verify the testing, but must document the results of the testing, or lack thereof. There are differences in the testing time allotments for each test as required by the pump manufacturer, apparatus builder and end user.

What is the 80 percent rule when dealing with apparatus voltage issues?
The alternator shall be tested as follows:

Start the engine and advance the throttle to 75 percent of maximum governed speed. Turn on enough electrical loads on the apparatus for the total draw to exceed the alternator output, adding load at the battery if necessary. With the proper test instruments attached to the alternator to record the maximum output, note the maximum output. If the total alternator output fails to reach or maintain 80 percent or the stated rated capacity the test fails. There are many more tests involved in the electrical system on the chassis, but this should answer your 80 percent question.

Please explain how the new engine emissions work with the DEF fluid.
Instead of me trying to present this in a one-description-fits-all, I will give you a couple of samples of what is done to describe the operations of the DPF/DEF 2010 EPA requirements. First, let’s pick a light duty chassis, like the GM Isuzu Duramax diesel.

Go to: http://chevrolet.com/content/dam/Chevrolet/northamerica/usa/nscwebsite/en/Home/Ownership/Manuals%20and%20Videos/02_pdf/SilveradoHD_DEF.pdf

Next, let’s go to one of the major diesel engine manufacturers, like Cummins Emergency Vehicle formatted engine descriptions:

Go to: http://cumminsengines.com/fire-and-emergency

I hope this gets you headed in the direction you desire and answers basic questions.

What would be good preventative maintenance that can be done on a routine basis to prolong the life of my emissions system?
This question is pretty common and easily answered. Because all manufacturers need to come to the same EPA mandates for emissions, they do things a little different to attain the same result. The best way to answer the question is to state what each engine manufacturer mandates, follow the instruction/maintenance manual to attain the desired results. Remember, short cuts means operational issues.

Wet pump or dry pump — pros and cons to both.

The dry pump is usually an operation of desire to leave the pump completely dry for operations in extreme cold climates. All drain valves are usually left open throughout the pumping system and outside of the tank. Other SOP’s may mandate the dry pump.

The wet pump is the norm. This gives the operator an immediate use of water without the need for priming or any additional setup or water hammer due to air in the hoses during initial setup. The only controversial issue is if you have a push pull valve controller for the tank-to-pump valve, do you have it set up for wet pump flow from tank with handle fully pushed in, or do you want the tank-to-pump control handle out during pumping from tank? In my department, where we have push/pull controls, we have the tank-to-pump valve open when the control is fully pushed in. This prevents accidents where the operator can run into or step on the control handle especially during night operations. The only time we pull the handle is to close the tank-to-pump valve for drafting ops.

— Ernie questions answered by Anthony D. (Tony) Bulygo.

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