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| PREVIOUS MONDAY NIGHT TRAININGS |
| SMOOTH BORE NOZZLE TRAINING |
We recently received three new smooth bore nozzles to add to our arsenal of nozzles for fire
extinguishment. The three nozzles will be placed on Engine 21 and on Ladder 26. Ladder 26 will get
two of the nozzles, one of the nozzles will go on the apartment pack.
Before we get into more specifics about the new nozzles, we should review nozzles in general. There is
much debate in the fire service when it comes to which types of nozzles are better, smooth bore or
combination. This debate has been ongoing for decades, and a clear winner has yet to emerge. The
best way to explain in it would be to say that each type of nozzle has it’s advantages and disadvantages,
know when to use which nozzle.
Smooth bore nozzles have many significant benefits. First, they operate at lower pressures, with a
minimum of 50 psi, as opposed to 75 and 100 psi for our other nozzles. That fact makes them ideal
choices for standpipe operations. Second, they tend to have higher flow rates at the same pressure
than combination nozzles. The final advantage is longer stream reach than combination nozzles at the
same pressure. As for the negatives, they do not offer the heat absorption characteristics and
ventilation capabilities that a fog nozzle does. So when do you use which nozzle? The list below is a
general list that explains which nozzle may be more effective than the other. As time goes by we will be
able to adjust how and when we use them and each firefighter may find one nozzle more effective than
the other for certain situations. Use your best judgment to make the right decision.
Typical uses for smooth bore nozzles:
Direct attack on an advanced fire or large fire
Defensive operations
Standpipe operations
Deep seated fires where penetration is important
Typical uses for combination/fog nozzles:
Indirect attack
Exposure protection
Hydraulic ventilation
Foam application
Specific details about the new nozzles
Our nozzles are being used with pistol type grips and are made by Akron Brass. There are many
options available in the market today when deciding on what type of setup you can use for your smooth
bore nozzles. Again, just like the debate on which type of nozzle is better (combination or smooth bore)
the type of smooth bore is debatable. Some options include stacked tips, slug tips, and multi-purpose
nozzles. Stacked tips allow you to manually change the size of the opening by simply unscrewing the tip
you don’t want. Slug tips allow you to unscrew a fog nozzle and leave a smooth bore to use. There are
also newer nozzles created that, by moving the handle, you can switch from smooth bore to fog. Either
way, be comfortable with our set-up if you use another set-up someplace else.
We are using the nozzles on our 1 ¾ “ lines. Depending on how things go, we may purchase tips for the
2 ½” lines. We will be using 7/8” tips, which is the largest tip you can use on a 1 ¾ “ line. The tip size
should never exceed 1/2 of the supply line size. A 7/8” tip will flow 161 gpm at 50 psi. Those are
numbers you should memorize for determining friction loss. Remember, a smooth bore nozzle will
deliver more flow if you increase the pressure. At 75 psi, the current operating pressure for our Assault
nozzles, a smooth bore could deliver nearly 200 gpm as opposed to 150 gpm. The problem becomes,
how many firefighters will it take to control the hoseline? There is no set rule, but 60-70 psi is the max.
extinguishment. The three nozzles will be placed on Engine 21 and on Ladder 26. Ladder 26 will get
two of the nozzles, one of the nozzles will go on the apartment pack.
Before we get into more specifics about the new nozzles, we should review nozzles in general. There is
much debate in the fire service when it comes to which types of nozzles are better, smooth bore or
combination. This debate has been ongoing for decades, and a clear winner has yet to emerge. The
best way to explain in it would be to say that each type of nozzle has it’s advantages and disadvantages,
know when to use which nozzle.
Smooth bore nozzles have many significant benefits. First, they operate at lower pressures, with a
minimum of 50 psi, as opposed to 75 and 100 psi for our other nozzles. That fact makes them ideal
choices for standpipe operations. Second, they tend to have higher flow rates at the same pressure
than combination nozzles. The final advantage is longer stream reach than combination nozzles at the
same pressure. As for the negatives, they do not offer the heat absorption characteristics and
ventilation capabilities that a fog nozzle does. So when do you use which nozzle? The list below is a
general list that explains which nozzle may be more effective than the other. As time goes by we will be
able to adjust how and when we use them and each firefighter may find one nozzle more effective than
the other for certain situations. Use your best judgment to make the right decision.
Typical uses for smooth bore nozzles:
Direct attack on an advanced fire or large fire
Defensive operations
Standpipe operations
Deep seated fires where penetration is important
Typical uses for combination/fog nozzles:
Indirect attack
Exposure protection
Hydraulic ventilation
Foam application
Specific details about the new nozzles
Our nozzles are being used with pistol type grips and are made by Akron Brass. There are many
options available in the market today when deciding on what type of setup you can use for your smooth
bore nozzles. Again, just like the debate on which type of nozzle is better (combination or smooth bore)
the type of smooth bore is debatable. Some options include stacked tips, slug tips, and multi-purpose
nozzles. Stacked tips allow you to manually change the size of the opening by simply unscrewing the tip
you don’t want. Slug tips allow you to unscrew a fog nozzle and leave a smooth bore to use. There are
also newer nozzles created that, by moving the handle, you can switch from smooth bore to fog. Either
way, be comfortable with our set-up if you use another set-up someplace else.
We are using the nozzles on our 1 ¾ “ lines. Depending on how things go, we may purchase tips for the
2 ½” lines. We will be using 7/8” tips, which is the largest tip you can use on a 1 ¾ “ line. The tip size
should never exceed 1/2 of the supply line size. A 7/8” tip will flow 161 gpm at 50 psi. Those are
numbers you should memorize for determining friction loss. Remember, a smooth bore nozzle will
deliver more flow if you increase the pressure. At 75 psi, the current operating pressure for our Assault
nozzles, a smooth bore could deliver nearly 200 gpm as opposed to 150 gpm. The problem becomes,
how many firefighters will it take to control the hoseline? There is no set rule, but 60-70 psi is the max.
| REMEMBER THESE NUMBERS! THEY RELATE TO OUR NEW NOZZLES: 7/8" TIP-50 PSI-161 GPM |
| Friction Loss Flow Chart |
| BHFD smooth bore orientation |
This is a document you can download to help you determine friction loss for both smooth bore and fog nozzles. In order to determine friction loss, first, we need to know the flow rate of our nozzles. The document you downloaded above has two charts on it. If you are trying to determine flow rate for smooth bore nozzles, you will need to use both charts to finally get your friction loss answer. If you are determining friction loss for fog nozzles, you can skip right to the second chart. Let's do a smooth bore example using our new nozzle. Have your chart ready. You arrive on scene at a working house fire in a 1 story wood frame ranch, no life hazard. You are the pump operator. Based on his scene size up, Capt. Drum has ordered the smooth bore line for the attack. The line is 250' long. You know that there is a smooth bore nozzle with a 7/8" tip. By looking at your chart or by putting it to memory, you know the nozzle will flow 161 gpm. If you dont remember the flow, use the top chart. Find 50 psi on the left side. Then find 7/8" tip size along the top. They should meet at 161 gpm. Youre ready to move to the bottom chart. Flow rates are on the left side. You know the flow rate is 161 gpm. Find the closest match to the flow rate. In this case it is 160 gpm. Along the top you have different hose sizes. Follow the 16p gpm row along the top until you get to 1 3/4". You should meet at 34 psi. That is the friction loss for every one hundred feet. In this example, the friction loss would be 85 psi. Take this number and add it to the nozzle pressure of 50, there is no elevation gain or loss and no appliance loss, so your total engine pressure is 85+50 or 135 psi. |