Auxiliary firefighter training

In this part of the "Practical Training of Auxiliary Firefighters" series, the operation and instrumentation of the pump are discussed.

Q: What are the three common meters on fire trucks?

A. Pressure gauge, vacuum gauge and compound gauge.

Q: What is the purpose of the pressure gauge on the pump?

A. The pressure gauge gives the pressure in pounds per square inch produced by the pump on the fire truck.

Q. What is the function of the vacuum gauge?

A. The vacuum gauge records the negative pressure or vacuum generated on the suction side of the pump. This vacuum can be created by pumping or drawing water from a water system with insufficient water flow.

Q. What is the role of compound rules?

A. The compound meter records vacuum or pressure. On the left side of the compound vacuum gauge zero (counterclockwise reading), the reading is displayed in "inch" vacuum. An inch vacuum refers to a vacuum equivalent to one inch of mercury. Since one inch of mercury is equal to 1.134 feet of water, a vacuum reading in inches is usually considered to be feet of water. Therefore, a reading of 10 on the vacuum gauge means that the negative pressure head or lift is 10 feet. Starting from zero, measuring clockwise, the reading indicates the pressure in pounds per square inch.

Q: Have the pressure gauge and compound gauge been calibrated in a form other than pound pressure?

A. Sometimes, the meter will be calibrated in "feet" of water column. Therefore, a reading of 200 on the pressure gauge means that the water head is 200 feet.

Question: Where are the various types of instruments commonly used on pumps?

A. The pressure gauge is usually located on the discharge side of all positive displacement pumps.

Vacuum gauges are usually not used for fire-fighting equipment, but when in use, they are placed on the intake side of the pump.

The composite pressure gauge is installed on the suction side of all pumps and is usually used to replace the direct pressure gauge on the discharge side of the centrifugal pump. The gauge displays the pressure received from the fire hydrant or the vacuum generated on the intake side, whichever occurs.

Question: When the pumping unit is put into use at draught, what is the first dilution to be done?

A. Choose a location as close as possible to the source of supply (ie rivers, lakes, creeks, etc.), but at the same time make sure that the pump is on a solid foundation. Ensure that the elevator at the selected location is fully within the engine's capacity.

Question: What measures can be taken if the ground next to the water body from which water is to be taken is not firm?

A. Place wooden boards or stones at the pump placement point to provide a satisfactory foundation.

Q. What precautions should be taken if a pump is placed on a wooden pier that has not been used recently?

A. Check the planks and supporting beams on the piers. If the planks rot or become visibly weak, other planks should be placed longitudinally on the dock, and the truck will roll on these planks. Using new planks that are loosely laid on the existing dock floor can distribute the load and reduce the possibility of the dock planks failing under the weight of the truck.

Question: If the pumping unit has been driven in place, is running from the draft from the surface source supply, and will be put into operation, what preliminary steps should be taken?

A. First check the brakes and use wedges under the wheels to prevent the truck from moving, especially when the ground is tilted. Before the driver leaves the truck, he should disconnect the drive of the axle and engage the gearbox in the appropriate gear for pumping. The shift lever lock should then be engaged to prevent accidental shifting. The throttle is then set to provide an idle speed slightly higher than normal.

Q: What is the procedure to connect the suction hose and get it ready?

A. The first step is to connect the length of the suction hose to be used. If the elevator requires two lengths, you should connect them first; if you need three lengths, connect the three parts before connecting to the pump.

After the lengths are connected. The rope is attached to the perforation at the end of the filter to provide a way to raise or lower the filter as needed.

After completing these connections, etc., the other end of the suction pipe is connected to the suction port on the pump, and the port is tightened. The pump is now ready to run.

Q: How deep should the filter be submerged under water?

A. The filter should be placed 1 1/2 feet or more below the water surface.

Q: Why is it necessary to place the filter at this depth?

A. Prevent air from entering the suction line. Incidentally, the aforementioned depth refers to the depth of the uppermost part of the filter below the water surface. ,

If the filter is allowed to stay too close to the surface, vortices will form, through which air enters the filter, and then enters the suction line into the pump from there. This air will destroy the effectiveness of the flow when it leaves the nozzle at the end of the pipeline.

Q: If the water depth of the water supply source is not enough to cover the filter, what measures should be taken to prevent air from entering the filter?

A. When the filter is immersed in water but the distance is short, by placing a wide plate or door on the water surface directly above the filter, it is very effective to check the formation of vortex and the air entering the filter.

Question: When the engine needs to pump water from the drain pipe, how far away can the filter be placed from the bottom of the stream?

A. It depends on the nature of the fluidized bed, or other sources of supply being used. If the bottom of a stream or other body of water is covered by leaves or other debris that may clog the screen, the filter should not be allowed to approach the stream bed, closer than a foot. The rope connected to the filter is fixed to an object on the shore to keep the filter at a proper level.

Q: If the water is not deep enough to leave a 12-inch gap between the filter and the bed (from a stream, pond, lake, or other water supply source), what precautions should be taken?

A. When the water depth is insufficient, place wooden boards, doors, ladders, metal plates, etc. between the filter and the bottom to prevent sand, stones, leaves and other foreign objects from being sucked into the pump.

The large wire, splint or mesh basket placed at the end of the suction hose is usually a valuable aid to the suction filter, especially when pumping water from water that contains a lot of debris. If time permits, a large box or bucket can be embedded in the water body to increase the effective depth of the end of the suction hose.

Q. After installing the necessary hose arrangement at the discharge port of the pump, what precautions should be taken after the pump is ready for operation?

A. Make sure that all drain valves and other connections are closed; make sure that the plug on the pump suction port (the suction hose is not connected) is tightly capped.

Question: When a positive displacement pump (piston or rotating gear) is put into operation, especially when starting the pump, what steps should be followed?

A. The first step is to open the drain door connecting the hose and close the mixing valve.

The pump gear is in the "capacity" state and the throttle is opened, turning the engine at a moderate speed.

There is no need to race the engine when starting.

After the water reaches the pump, the pump is activated, and the motor accelerates to such a point in order to provide the required water pressure on the engine.

If the pipeline is very long or the pump requires higher pressure, the pump control will switch to "pressure".

By the way, when performing such a change from pressure to volume or volume to pressure, the throttle valve is delayed during operation.

Q: What are the starting steps for centrifugal pumps?

A. First, close all drain valves, and close the mixing valve (if any). If the pump is a parallel series type, set the control valve to "capacity" or "pressure" as needed. If the pump is equipped with an auxiliary rotary priming pump, engage the priming pump and increase the speed slightly.

If the pump is equipped with an auxiliary vacuum start from a motor (or similar device), engage the centrifugal pump impeller and open the vacuum connection valve; increase the speed very slightly.

When the pump is started, it will be noticed by the water discharged by the auxiliary start pump or the pressure record in the vacuum start centrifugal pump. Loosen the starter pump and engage the centrifugal pump impeller at the same time, or close the vacuum control valve.

When the discharge valve opens, slowly increase the speed to maintain sufficient pressure in the pump. After the valve is opened, advance the throttle until the desired engine pressure is displayed on the gauge.

When the required pressure is obtained, set the safety valve or governor to a few pounds higher than the required working pressure; it is generally considered that about 5 pounds higher than normal pressure is sufficient.

Open the cooling water supply control valve to keep the motor temperature within the range recommended by the manufacturer.

If a tachometer is provided, observe the motor speed from time to time. Also frequently observe the water temperature, oil pressure, fuel and water pressure gauges.

Q: What steps need to be taken when the pump is shut down after operation?

A. If the downtime is short, there is no need to disengage the trump gear. With the pipeline closed and the stirring valve open, delay the throttle valve to maintain approximately 25 pounds of pressure. To resume operation, simply open the pipeline, close the stirring valve and push in the throttle valve.

To close it permanently, delay the throttle, open the stirring valve, close the discharge valve, disconnect the pump gear, close the auxiliary cooling line, discharge hose line, drain pump and disconnect the suction and discharge hoses.

Question: Where suction is drawn from a fire hydrant instead of through the draft, what steps are usually followed when putting the pump into operation?

A. First, the location of the pump facilitates connection to the selected fire hydrant. The suction hose is connected to the suction port of the fire hydrant and pump, and precautions are taken to ensure that gaskets are provided and the connection is tight.

Then close the drain valve on the pump, and close the stirring valve and all drain valves. Make sure that the cap on the suction port on the other side of the pump is tightened. Turn on the fire hydrant.

When the line is ready for use. Engage the pump shift lever to the proper position. Open the discharge gate valve and fully advance the throttle valve to obtain the required pressure shown on the pressure gauge. observe. The safety precautions described in the method of operating the pump from draught include setting a safety valve or governor, opening the cooling water valve, and observing gauges and indicators.

Question: If the pressure on the suction side of the pump working at the fire hydrant shows a severe pressure drop, what does this indicate?

A. This usually means that the main faucet connected to the fire hydrant is required to provide more water than it can deliver.

By the way, if the pressure on the suction side of the pump shows less than 5 pounds, it is best to reduce the discharge of this pump by closing one of the lines or reducing the size of the nozzle. When pumping from a fire hydrant, under no circumstances should the pump be operated under vacuum.

Q: When the fire truck returns to the dormitory from a fire, what inspections are usually recommended?

A. Check the oil volume and condition in the crankcase, and add oil if necessary. If the oil is too thin or there are too many foreign objects, drain and replace with new oil.

Check the fuel tank and fill it up if necessary. Check the water in the radiator. If necessary, add water.

Check important lubrication points: check for missing or loose parts and report.

Clean the entire equipment and thoroughly dry all rusty parts.

Prepare the device to respond to the next alarm immediately.