Cold Weather Operations

COLD WEATHER OPERATIONS

BY TERRY ECKERT

How knowledgeable are you about the proper operating of fire apparatus in cold weather? Taking the following test will give you some indication.

1. Will water always freeze when it gets below 327F?

2. List four ways frozen hose fittings can be taken apart.

3. When the temperature is below freezing, is it better to use the wet pump or the dry pump?

4. If water freezes in an air brake line, will the brakes automatically engage?

5. Does the windchill factor affect fire apparatus?

The answers to these questions are given in this article. As you read, make some mental notes on ways you can spec your pumper for operating in cold weather.

QUESTION 1

I recently administered a test to a group of firefighters applying for an engineer position. As part of the test, I formulated some simple oral questions. The first question I asked was, “What is the freezing temperature of water?” When a few of the test- takers hemmed and hawed, I explained that this was not a trick question–that I wanted to know the freezing temperature of water. I received answers ranging from 207F to 357F. When I pressed the test-takers to learn where they had obtained their information, most of them said they didn`t know. But one future engineer who was a quick thinker and really trying to impress me stated, “The normal freezing temperature is 327F, but as long as the water moves, it will resist freezing at temperatures way below its normal freezing temperature.”

I thought to myself, the next time I ask this question I`m going to have ask, “What is the normal freezing temperature of static, pure, distilled water?” That way, I wouldn`t be accused of asking a trick question.

The point I`m trying to make is that water just does not want to freeze while moving. This helps make firefighting possible in subzero weather. You have to keep the water moving. Never let the water sit; drain it quickly, or move it. Make a mess on the road if you have to. That`s why there are city salt trucks. If you need to keep open a hydrant that is not flowing, use a hose and circulate the water to the nearest ditch or sewer to keep your pump, plumbing, and hydrant from freezing. Remind your firefighting crew not to shut the nozzles down completely until they are ready to pick up. In cold weather, keep that idea in your mind–keep it moving.

QUESTION 2

I know from personal firefighting experience how difficult it is to pick up hose that is frozen solid with water, so remember to be prepared to take the fittings apart and drain them quickly before shutting down your lines. If the fittings are frozen, have equipment ready to thaw them out. You can separate fittings in a number of ways, such as by using a propane torch or road flares, soaking the fitting with pure antifreeze from a spray bottle, using the water from a still charged hoseline, or tapping the sides of the fittings with a hammer.

Freezing water is apparatus` biggest enemy during cold weather operations, so consider the following advice and ideas.

Prep the pumper during morning checkout.

Make sure you open all the bleeders to drain any water that might still be in the lines.

Drain all pressure and intake relief valve drains, if so equipped.

Drain the front suction along with the prepiped monitor. Some monitors have drains built into them; some can be drained by uprighting the device. You may have to remove the device to drain others. Whatever it requires to drain the water, just do it! I promise you that you will save yourself a lot of headaches later.

If your apparatus has a monitor waterway plumbed so the ball valve is on a vertical riser, some water will remain on top of the waterway discharge valve. The bleeder/ drain is above the valve and will not remove all of the water. To remove the water, first make sure the monitor is drained and the pump is out of gear. Then drain some of the water out of the pump. With the drain still open, open the waterway discharge valve. This drains the rest of the water sitting on top of the valve into the pump and also will remove all the dirt and rust that sometimes cause the valve ball and seat to fail. This method also works for any other discharge valves on vertical piping such as on preconnects or rear discharges.

Always drain and dry front discharges or intakes. Drain all the bleeders in the plumbing forward of the valve. If there is no drain on all the low points, you may have to use compressed air to clear water from the piping.

A frequent problem encountered by driver/operators in winter is that the discharge and intake caps freeze and cannot be re-moved. Some driver/operators like to use a coating of grease on the threads. This works but presents some disadvantages such as the mess it makes and the damage it causes to the rubber gaskets. An alternative is to use straight automotive antifreeze to coat the cap threads. Not only will this help keep the caps from freezing, but it will not attack the rubber gaskets, and its additives will protect the metal from corroding. Keep a spray bottle of antifreeze (use it straight, not the 50-50 mix) in the engineer compartment. The antifreeze will also work as a temporary fix in the field when the door latches freeze.

QUESTION 3

Which is better: a wet or a dry pump? This is a loaded subject; engineers will argue it for hours on end. There are pros and cons to both methods. Climate, staffing, the number of calls, the time of year, the average distance to calls, the condition of the apparatus, and personal preference will dictate whether you want to keep water in your pump. We will look at both methods.

Dry Pump

The theory behind the dry pump method is very simple: If you keep the pump dry and void of any water, it cannot freeze. To set up for dry pump operation, completely drain the pump and all valves, piping, and fittings. Compressed air is helpful in re-moving the water. With the pump charged with compressed air, open up each discharge and intake valve one at a time (with caps removed) until all the water is removed. After draining, a dry prime test is highly recommended. This will not only check the tightness of the pump, tank fill, and tank valve but will also help keep the primer gears from freezing by pushing all the water out and replacing it with oil. After the dry prime, relieve the vacuum by opening up the drain again just to make sure that no water escaped through the tank valves and entered the pump.

Pros of the Dry Pump

Advantages of the dry pump include the following:

• The pump and most of the plumbing are protected from freezing.
• The apparatus may be left outside for long periods of time with the engine off or without having to put the pump in gear.
• The apparatus can travel long distances without freezing the pump and plumbing.

Cons of the Dry Pump

Among the disadvantages of the dry pump are the following:

• The pump must be primed whenever water is needed.
• Any tank valve leakage may cause small amounts of water to go into the pump and freeze quickly.
• The tank-to-pump valve has water on one side and air on the other and is easily frozen in the closed position, thus preventing getting water from the tank.
• It takes time to set up the dry pump.
• You are still returning from the fire scene with a wet pump.
• Pump packings can dry up.
• All the ball-valve assemblies are dry and unlubricated.

Criteria for Using Dry Pump Protocol

The dry pump protocol may be used under the following conditions:

• The volume of fire calls is light.
• Apparatus travel long distances to calls.
• The climate is excessively cold.
• The pump and valves are in good shape and leak-free.
• The apparatus may be sitting outside unattended for a long period of time.

Wet Pump

The wet pump method works by using the volume of water stored in your water tank to your advantage. With proper apparatus and pump operation, pump freezing can easily be avoided. The combined pump and tank water is of such a volume that it would take a vast amount of time to get to freezing temperature. Also, with pump recirculation, moving water will resist freezing. Theory also tells us that recirculating water creates heat. It may be unnoticeable to touch in subzero temperatures, but physics tells us that moving water does in fact create heat. The faster the water moves, the more heat it creates–what a good reason for using the fast idle controls.

Setting up for wet pump operations is simple. To make sure the pump is full when the apparatus is not in use or is sitting in quarters or driving down the highway, leave both tank valves open (tank fill and tank-to-pump). This will also induce a movement through convection that will try to equalize the temperature of the water in the pump to the water in the tank. When arriving on a fire scene, tank water will always be accessible even if the tank valve or leakage freezes because it will freeze in the open position. Even if the tank fill valve freezes, open proper discharge pressure could probably still be obtained.

Pros of a Wet Pump

The advantages of a wet pump include the following:

• The pump is already primed, and an immediate water supply from the tank is possible.
• Pump packing stays wet.
• Leaking tank valves will not affect the pump`s freezing.
• Circulating water will keep the tank and pump water warmer.
• Pump water is the same temperature as the tank water.
• Ball-valve assemblies stay wet and lubricated.

Cons of a Wet Pump

Among the disadvantages of a wet pump are the following:

• The driver/operator must be educated in recirculating pump tank water.
• Failure to circulate water may result in a frozen pump or frozen plumbing.
• Some discharge valves may freeze, and you may have to use different discharges in their place.
• Front intakes and discharges still have to be drained.
• In extreme cold, you cannot cap the external intake relief valves, if so equipped, because of possible valve leakage.

Criteria for Using Wet Pump Protocol

The conditions under which the wet pump protocol are used include the following:

• The volume of fire calls is medium or heavy.
• Apparatus travel a short distance to calls.
• It can be used in any winter climate.
• Discharge intake valves should be in good shape and leak-free.
• Apparatus should not be left outside unless the pump is in gear and water is recirculating.
• The pump packings are in good condition and are kept in proper adjustment.
• Storage outside has to be kept to a minimum.

Whether to use a wet or dry pump, therefore, would depend on conditions.

Temperature of the Apparatus Bay

Every department has its bean counters who believe that by lowering the temperatures in the apparatus bays, they will save money. In effect, the money man trying to save on the heating bill unknowingly increases the cost of vehicle maintenance. A 107F warmer temperature on 500 gallons of water means that it would take a few more hours for that water to get to its freezing temperature. A cold apparatus bay temperature also directly affects the performance of the engine and transmission when responding to a call, causing considerably more wear and tear on the driveline parts. Please keep the apparatus bay warm!

Engine Block Heaters

Engine block heaters are real engine savers. Since most engine wear occurs during warm-up, a block heater interfaced with an auto-eject really does make sense, even with the apparatus housed inside.

The Engine Cooler

The engine cooler knob mounted on the pump panel should remain in the “off” position, because running with this valve open would keep the engine from heating up. In the winter, many diesel engines will not even get to operating temperature at idle. Fast idle will help keep the engine warmer.

QUESTION 4

Don`t forget about the braking system. The biggest concern here is water in the brake system. If ice should form in an air brake line, the ice will cut out the air supply to whatever is downline in the system. If ice blocks the supply to the air storage tanks, low-air warnings will engage and warn the driver/operator of a problem. If ice forms in the parking brake lines, there would be no low-air warning, and the parking brakes could engage without warning.

On the other hand, if ice should block the air delivery in the service brake system (regular foot brake), the brakes may not operate on one, two, or all of the wheels–and all this without warning from any low-air warning system. Sometimes the only way to stop the apparatus would be to manually engage the parking brake. To help avoid these problems, make sure you drain tanks daily. If any drivers are somewhat vague in their knowledge of air brake operation and emergency stopping, set up some professional training classes.

Apparatus Storage

Store your apparatus inside whenever possible. To leave the apparatus outside unnessarily in subzero temperatures is a gross misuse of equipment and taxpayers` dollars. It also can jeopardize firefighters` lives. When the “Big One” occurs, the apparatus had better not be outside and half-frozen before the job even begins. Hopefully, the apparatus is warm, cozy, and ready to roll!

QUESTION 5

The windchill factor was invented by some genius to make it sound colder than it really is. The windchill factor is the measurement of the effects of the outside temperature combined with the wind speed on bare human skin. A human being may cut the windchill effect by putting on some extra clothes.

The temperature of a piece of steel will go no lower than the outside real temperature whether the wind is blowing at 0 mph or 50 mph. But the wind does affect the time it takes your equipment to cool down. The higher the wind speed, the faster equipment will lose its heat. However, the temperature of the equipment will not fall below the real temperature. Apparatus are most directly affected by the wind when driven down the road, hence the concern when responding long distances. The apparatus and all its equipment (including the water in the tank) will cool down at an extremely faster rate at highway speed than while sitting still. Keep this in mind when making your cold weather decisions.

The best advice I can give with regard to preparing your apparatus for the cold months is to be prepared. I recommend a late fall training session for the crew to remind the driver/operators of the procedures your department has developed so that everybody is on the same wavelength when it comes to cold weather operations. As old apparatus are replaced, new cold weather procedures may have to be developed. Be open to the changes; be open to suggestions from other driver/operators. Standard operating procedures or guidelines are good in some ways; but when things start freezing, department protocol may not always be the best approach.

According to an article that appeared in the Chicago Tribune (September 18, 1998): “The approaching cold season may prove much different than the last–more volatile and subject to bouts of storminess and wide temperature swings, including more frequent, but progressive, arctic cold air outbreaks.” Be prepared to deal with these problems; and remember, Spring is just five months away! n

(Top) Heavy-duty weather conditions may call for a heavy-duty solution. Here, a large propane torch is used to thaw fittings. (Photos by Gordon J. Nord, Jr.) (Middle) Firefighters use salvage covers to cover the hosebed and the cab to prevent layers of ice from forming from the mist of the deluge operation. This improvisation saves hours of thawing out equipment, and the pumper can be returned to service more quickly. (Bottom) Freezing water is apparatus` biggest enemy during cold weather operations.

TERRY ECKERT, a 15-year veteran of the fire service, is a firefighter and head of apparatus maintenance in the Darien-Woodridge (IL) Fire District and the chief engineer of the Westmont (IL) Fire Department. He has 25 years of experience as a vehicle technician. He is an ASE-certified master automobile technician and master heavy truck technician and an EVT Level 3 master technician. He also has ASE certification in advanced level engine performance. Eckert is a member of numerous professional associations, including the National Association of Emergency Vehicle Technicians (NAEVT) and the Illinois Fire Apparatus Mechanics Association. He is a member of the EVT Certification Commission, where he serves on the Validation Committee and had chaired the E-3 section, and the NFPA Technical Committee on Emergency Vehicle Technician Professional Qualifications. He was the 1997 recipient of the NAEVT Certificate of Achievement Award.