Apparatus, Chassis Components, Maintenance, Naylis, Pumpers, Pumps

Regular Air Tank Bleeds Should Be a Part of Regular Maintenance Checks

Issue 9 and Volume 25.

By Jerry Naylis

During a recent annual apparatus test on a 2½-year-old quint, the test technician exercised the air-actuated pump transmission shift lever.

This shift lever moves the motor’s power from the drivetrain to the pump. The technician placed the transmission in the neutral position and proceeded to move the shift lever for the pump. He expected to hear a slight air discharge as he executed the procedure. What actually happened startled him. Water started coming out of the air-actuated valve!

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The technician quickly put the shift lever back in the road position. He waited approximately five seconds and again attempted the maneuver with exactly the same result. After moving the shift lever back to the road position, he began to look for the reason water was coming out of the air-actuated shift lever. The air line appeared to be intact and did not show any signs of tampering or being cross connected with any water lines, so what could have caused water to come out of this air-actuated valve when operated?


As the puzzled technician relayed the situation to me, I asked a few basic questions to get some background data. The apparatus was 2½ years old. Did the apparatus have annual pump service tests and annual aerial inspections starting with the year after delivery? The surprising answer was no. Evidently, the then fire chief felt a “new” apparatus didn’t need annual service tests or inspections, and he believed he could save some budget dollars by deferring the inspections and service tests. My immediate thought recalled the old adage “penny wise and pound foolish.”

I then asked if the apparatus was given any regular or periodic maintenance checks. I wasn’t surprised when I was told the fuel tank was religiously topped off if the fuel gauge dropped to ¾. Beyond that, nothing.

Armed with this information, I told the technician to get a bucket and to locate the apparatus air tanks. I told him to place the bucket under the tanks’ air bleeder valves to collect any condensate that came out. This particular truck had three air tanks.

He opened the first two air tanks and bled them with hardly any moisture coming out. The third tank was a completely different story. When he opened the third air tank bleeder valve, approximately ½ gallon of water came out. Further questioning revealed that these air tanks had never been bled since the original delivery date some 30 months prior to the test.


The air tanks provide air pressure for the air brakes, air horns, and air-actuated pump transmission transfer switch. The makeup air for these tanks comes from the ambient atmosphere. This fire department is located in the northeast United States, where humidity can be high at times over the course of the year. Failing to bleed the air tanks allowed moisture to collect in the air tanks. The condition was found when the air-actuated pump transmission transfer switch was exercised during the apparatus inspection ordered by the new fire chief.

The back end of an air horn buried in the bumper with the air line feed from the air tank.

1 The back end of an air horn buried in the bumper with the air line feed from the air tank. (Photos by author.)

An air tank with a ¼-turn bleeder valve on the bottom of the air tank.

2 An air tank with a ¼-turn bleeder valve on the bottom of the air tank.

Two air tanks with individual ¼-turn bleeder valves.

3 Two air tanks with individual ¼-turn bleeder valves.

If this condition had gone unnoticed, it is very likely that the air lines for the brake system, the air horns, and the pump transmission transfer switch could have frozen if the apparatus was exposed to freezing temperatures for an extended period of time.

This situation reinforces several extremely important points. First, annual pump and aerial inspections are critical and need to be done every year. Second, all onboard air tanks need to be bled to remove any moisture that may accumulate on a regular basis. At the very least, this should be done weekly. This is needed to prevent the air system from failing to operate. It is also necessary to prevent the tanks from rusting on the inside and failing. A total failure of the air tanks could lead to a catastrophic event that could result in serious injury to firefighters.

As with all maintenance, bleeding air tanks is a regular maintenance item that needs to be recorded. Whether your department uses electronic record keeping or writes this data in a logbook, the fact is that action items like this need to be documented. You may find that the air is causing excessive moisture to collect in the air tanks. This type of data could support a budget request for an automatic air dryer to remove moisture while the apparatus is operating. An air dryer doesn’t replace the need to regularly bleed the air tanks but will aid in preventing a massive buildup of moisture in them. A weekly apparatus checklist should include a segment reminding the operator to bleed the air tanks and record how much moisture came out. These records should be reviewed periodically to spot trends and potential problems.

JERRY NAYLIS has served in career and volunteer fire departments for more than 40 years. He has a bachelor’s degree in fire science from Jersey City State College and a master’s degree in administrative science from Fairleigh Dickinson University. He is a NJ-certified fire instructor and has taught at FDIC International and throughout the United States, Canada, and the United Kingdom on a variety of fire-related topics.