| MONDAY NIGHT TRAINING |
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| PREVIOUS MONDAY NIGHT TRAININGS |
| TEST |
| Monday Night Training For July 30th |
hydrants is one way we can determine how much water is actually available from a
particular hydrant. This information is usually gathered as part of a pre-plan for a
particular building or location. Before we start talking about the procedure for
doing a hydrant flow test, let's take a few minutes to discuss GPM's so the answer
we get from doing our flow test makes sense. It doesn't make much sense to do
our flow test and come up with a flow rate of let's say, 1,000 GPM, when you aren't
sure exactly how that number plays into your fire operations.
In order for your hydrant flow test results to make sense, let's look at how much
water is required to put out fires. There are two basic formulas out in the fire
service that are used to determine how much water would be required to put out a
fire. The two formulas are the National Fire Academy formula and the Iowa State
formula.
This is the Iowa State formula
1. Formulas: Volume (in cubic feet) of area involved divided by 100 = GPM flow
necessary for 30 seconds
2. Volume (in cubic feet) of area involved divided by 200 = gallons of water needed
13 ft. times 16 ft. times 8 ft. = 1,664 cu. ft.
1,664 cu. ft. divided by 100 = 16.6 GPM for 30 seconds
1,664 cu. ft. divided by 200 = 8.3 gallons of water required
Now the simpler National Fire Academy Formula
Simplified formula developed by National Fire Academy
1. Determine the area of the structure (length times width)
2. Divide the area by 1/3 to determine GPM for fire area
3. Allow 25% for each exposure including another room, floor or structure
4. Determine percentage of involvement to determine water delivery needs
13 ft. times 16 ft. = 208 sq. ft.
208 sq. ft. divided by 3 = 69 GPM
1 interior exposure (25%) 69 GPM times 25% = 17 GPM
No exterior exposures
Total Required Fire flow 100 GPM*
* Rounded to nearest 100 GPM
Flow shown for single area or floor of involvement, must be increased for multiple
areas or floors
Note the closeness of results in the methods after discounting the allowance for
the interior exposure in the last method.
Remember what our nozzles are capable of:
Our Fixed Pressure, Fixed Gallonage nozzles: 150 gpm at 75 psi
250 gpm at 75 psi
Constant Pressure, Adjustable Gallonage : 95-150 gpm at 100 psi
Now that we have all that stuff down, here's how we go about doing the hydrant
flow test:
NOTE: The best time to do a hydrant flow test is sometime in the morning when the
demand is the highest. If you're doing a test in a commercial area, you might
accidentally set off water flow alarms in buildings with sprinkler/standpipe systems.
1. Locate the building or location you want to test. If it's a building, locate the
hydrant closest to the building. If your're just interested in testing the street in
general, locate the most dead end hydrant if possible.
2. You will need to find a total of two hydrants. The first you already located, that is
called the "test hydrant".
3. Locate the next hydrant in line from the test hydrant, that will be called the "flow
hydrant".
4. Open and flush the test hydrant. After flushing, close the hydrant and attach the
pressure gauge. After applying the pressure gauge, re-open the hydrant
completely. Make sure the petcock is open on the pressure gauge to bleed out any
air. Make sure when flushing the hydrant you try not to damage any property by
taking any precautions you can.
5. With the hydrant fully open, record the reading on the pressure gauge. This is
the static pressure of the system. Write this number down, you will need it later.
6. Opening the flow hydrant will be the next step in the process. However, you will
need to do a few things before opening the flow hydrant. The first thing to do is
check the inside of the 2.5" opening and see how the 2.5" discharge opening is
formed. It can be formed in one of 3 ways:
You will need the coefficient later to plug into a formula. You will also need to take
your ruler and measure the 2.5" opening and get an accurate measurement to the
1/16 of an inch.
7. Assign someone else to open the "flow hydrant". Make sure the flow hydrant is
flushed prior to use and the same precautions used for the test hydrant to prevent
damage should be taken.
8. Open the flow hydrant completely. Remember, use only the 2.5 outlets on the
hydrants, not the steamer. There is too much air mixed in with the steamer to get
accurate readings. With the flow hydrant open completely, you will need 2
readings. The first reading would be the residual pressure at the test hydrant.
Remember, water has to be flowing to get that reading. Write down the residual
pressure reading.
9. The next step involves getting a reading from the Pitot gauge. Insert the gauge
half the distance of the opening you are measuring away from the end of the
discharge opening. For example, on a standard 2.5" opening, hold the pitot gauge
1.25 inches away from the discharge opening. make sure your petcock is open
and the air is bled from the gauge before obtaining your reading. If the reading is
bouncing around, get the number in the middle. Write down that Pitot reading.
10. You now should have three readings. 1: Your static pressure reading 2: Your
residual pressure reading, and 3: Your pitot gauge reading (also known as flow
rate). You can now plug those numbers into the following formula:
Q=GPM
C=Hydrant Coefficient
D=Diameter Of Hydrant Opening (In decimal form)
P=Reading on Pitot Gauge
particular hydrant. This information is usually gathered as part of a pre-plan for a
particular building or location. Before we start talking about the procedure for
doing a hydrant flow test, let's take a few minutes to discuss GPM's so the answer
we get from doing our flow test makes sense. It doesn't make much sense to do
our flow test and come up with a flow rate of let's say, 1,000 GPM, when you aren't
sure exactly how that number plays into your fire operations.
In order for your hydrant flow test results to make sense, let's look at how much
water is required to put out fires. There are two basic formulas out in the fire
service that are used to determine how much water would be required to put out a
fire. The two formulas are the National Fire Academy formula and the Iowa State
formula.
This is the Iowa State formula
1. Formulas: Volume (in cubic feet) of area involved divided by 100 = GPM flow
necessary for 30 seconds
2. Volume (in cubic feet) of area involved divided by 200 = gallons of water needed
13 ft. times 16 ft. times 8 ft. = 1,664 cu. ft.
1,664 cu. ft. divided by 100 = 16.6 GPM for 30 seconds
1,664 cu. ft. divided by 200 = 8.3 gallons of water required
Now the simpler National Fire Academy Formula
Simplified formula developed by National Fire Academy
1. Determine the area of the structure (length times width)
2. Divide the area by 1/3 to determine GPM for fire area
3. Allow 25% for each exposure including another room, floor or structure
4. Determine percentage of involvement to determine water delivery needs
13 ft. times 16 ft. = 208 sq. ft.
208 sq. ft. divided by 3 = 69 GPM
1 interior exposure (25%) 69 GPM times 25% = 17 GPM
No exterior exposures
Total Required Fire flow 100 GPM*
* Rounded to nearest 100 GPM
Flow shown for single area or floor of involvement, must be increased for multiple
areas or floors
Note the closeness of results in the methods after discounting the allowance for
the interior exposure in the last method.
Remember what our nozzles are capable of:
Our Fixed Pressure, Fixed Gallonage nozzles: 150 gpm at 75 psi
250 gpm at 75 psi
Constant Pressure, Adjustable Gallonage : 95-150 gpm at 100 psi
Now that we have all that stuff down, here's how we go about doing the hydrant
flow test:
NOTE: The best time to do a hydrant flow test is sometime in the morning when the
demand is the highest. If you're doing a test in a commercial area, you might
accidentally set off water flow alarms in buildings with sprinkler/standpipe systems.
1. Locate the building or location you want to test. If it's a building, locate the
hydrant closest to the building. If your're just interested in testing the street in
general, locate the most dead end hydrant if possible.
2. You will need to find a total of two hydrants. The first you already located, that is
called the "test hydrant".
3. Locate the next hydrant in line from the test hydrant, that will be called the "flow
hydrant".
4. Open and flush the test hydrant. After flushing, close the hydrant and attach the
pressure gauge. After applying the pressure gauge, re-open the hydrant
completely. Make sure the petcock is open on the pressure gauge to bleed out any
air. Make sure when flushing the hydrant you try not to damage any property by
taking any precautions you can.
5. With the hydrant fully open, record the reading on the pressure gauge. This is
the static pressure of the system. Write this number down, you will need it later.
6. Opening the flow hydrant will be the next step in the process. However, you will
need to do a few things before opening the flow hydrant. The first thing to do is
check the inside of the 2.5" opening and see how the 2.5" discharge opening is
formed. It can be formed in one of 3 ways:
You will need the coefficient later to plug into a formula. You will also need to take
your ruler and measure the 2.5" opening and get an accurate measurement to the
1/16 of an inch.
7. Assign someone else to open the "flow hydrant". Make sure the flow hydrant is
flushed prior to use and the same precautions used for the test hydrant to prevent
damage should be taken.
8. Open the flow hydrant completely. Remember, use only the 2.5 outlets on the
hydrants, not the steamer. There is too much air mixed in with the steamer to get
accurate readings. With the flow hydrant open completely, you will need 2
readings. The first reading would be the residual pressure at the test hydrant.
Remember, water has to be flowing to get that reading. Write down the residual
pressure reading.
9. The next step involves getting a reading from the Pitot gauge. Insert the gauge
half the distance of the opening you are measuring away from the end of the
discharge opening. For example, on a standard 2.5" opening, hold the pitot gauge
1.25 inches away from the discharge opening. make sure your petcock is open
and the air is bled from the gauge before obtaining your reading. If the reading is
bouncing around, get the number in the middle. Write down that Pitot reading.
10. You now should have three readings. 1: Your static pressure reading 2: Your
residual pressure reading, and 3: Your pitot gauge reading (also known as flow
rate). You can now plug those numbers into the following formula:
Q=GPM
C=Hydrant Coefficient
D=Diameter Of Hydrant Opening (In decimal form)
P=Reading on Pitot Gauge
Pitot Tube Pressure Gauge Flow Chart Hydrant Wrench Pad And Paper Ruler Portable Radios Several Firefighters To Do The Test |
