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current debate at work
which size tip is going to give you the farthest effective reach? provided both are pumped at the same nozzle pressure, same angle, same environmental factors.
1" tip
1 3/4 tip
and why?
The orginal discussion was which tip is going to give the farthest effective reach 1" or 1 1/8". However after inital quick field test the difference was to little to note. So we changed the tip sizes to a greater difference and haven't tested it yet.
Couldn't find my copy of "Hydraulics for Firemen" by Theobald but the tests performed by FDNY for the City College of New York and reported in the above text from 1927, indicated that an effective reach for master streams could be estimated in still air as follows:
Nozzle pressure divided by two plus 45 will yield the approximate reach in feet. The oldest IFSTA in my library (1972) for "Fire Stream Practices" shows a graph on page 49 where the 50 psi hand line nozzle has an effective reach of 80 feet. The effective reach is specified as having 90% of the stream in a 15 inch circle and also 75% inside a 10 inch circle. Controlling factors are listed as: 1. Velocity of the stream at the exit of the nozzle.
2. Volume of water for the same stream velocity. 3. Horizontal reach is greatest at 32 deg. above flat ground. 4. Wind is still or less than 5 MPH.
This apparently has been an ongoing discussion for over 100 years, with similar results for anyone who has tried to determine fire stream reach.
KuhShise- **** if you dont have the direct answer then nobody will. I figured you would have a three page explination on it. Thanks for the page number we have that book in the station library i think. I will check it out.
And the debate goes on
Quote:
Originally Posted by RFD21C
Comparing the 1 inch hand line tip with the 1-3/4 inch master stream tip is like comparing males and females. No comparison.
Yes there 1-3/4 will give more water and a better stream as well as reach.
You may have meant the 1 inch tip vs. the 1-1/8 or the 1-1/4 inch tip. The 1-1/8 and the 1-1/4 inch tip will give more water and reach. The shape of the stream is dependent on the condition of the tip facing. If there are nicks on the opening, discharge, of the tip, the stream will not be as good as one with the tip being smooth.
We started using a 1inch tip on one of the preconnects back in the 1990's with I was at the fta, telling companies they will be a quicker knock down especially at apartments and the like where they have a longer stretch to the fire.
Are you sure or just saying this because it seems to make sense on the surface. What's the science? I think KuhShise noted well why the diameter may not matter, given the same tip pressure, angle, wind, bur free orifice, etc.Quote:
Originally Posted by CaptOldTimer
FACT!Quote:
Originally Posted by RFDACM02
Did you not read the OP's question??
1 inch tip vs. a 1-3/4 tip? A 1-3/4 inch tip is a master stream tip.
He may have meant to say 1-1/4 inch tip and not a 1 -3/4 inch tip, I have no idea.
I can tell you that a 1-3/4 inch tip will give more water and reach further than a 1 inch tip.
He asked about reach, not the amount of water, which is obviously a no brainer.Quote:
Originally Posted by CaptOldTimer
Quote:
Originally Posted by RFD21C
Captain yes you are correct in that the orginal debate was over the stacked tips on a 2.5. Currently we have a three stack tip of 1", 1 1/8" 1 1/4". the debate started over on a fire the nozzleman (from another company) pulled the 2 1/2 and never removed the 1" tip(209 gpm) . So afterwards when we were talking about the fire we were disscussing it. I was asking why leave the 1" tip on the stack tip. If we are only going to flow 209gpm through a 2 1/2 then why pull the 2 1/2. We can get that flow through a 1 3/4. By removing the 1" we would get a flow rate of 265 gpm, worth the weight of the 2 1/2. Why not keep the 1" tip off the stack tips all the time? The response I got was the 1" tip will give you more reach than the 1 1/8", so it is good to keep the 1" tip with you. I threw the BS flag. After testing the two tips the reach was about the same, maybe a foot more on the 1 1/8" tip. Being both headstrong firemen, neither would concede to one another.
After researching the topic some more we found in Clarks Firefighting Priciples & Practices John Freeman's definition of effective reach and his tables he created in 1888 (pg 278). His tables show that the larger the size the greater the reach. 1" tip about 63 ft. compared to a 1 1/2 tip of 73ft considering all thing equal.
My question is more about the why a larger stream produces a greater reach then a small stream. What are the physics behind it? Since this forum has people such as KuhShise that understand and are very good at explaining not only the how but the why in regards to these type questions. I created this thread to get an answer.
Yes i am throughly aware of the fact that an 1 3/4 tip is a master stream tip and a 1" tip is handline tip.
Lets see if I can help you on this, without getting too complicated in algebra definitions and equations.Quote:
Originally Posted by RFD21C
Water has mass, meaning weight. How that is used to give a longer reach on a large (1-1/2" tip) compared to the small (1" tip) is controlled and effected by turbulence, pressure, velocity, linear and laminar flow.
With pressure being the same on both tips, turbulence plays a small roll. Through the small tip, there is alot of turbulence, and that effects the mass in a straight line. Once it leaves the tip, it is not organized, and the mass of the water doesn't stay in place. Kinda like no "weight" behind the push. On a large tip, you keep the mass together, and effectively it will reach further. Drag is also less on the large tip, compared to the small tip. So you keep that mass moving in a more controlled stream.
Essentially, if the nozzle tip is small, it will have high velocity. Small streams have less mass, and are affected by drag more because of the lack of mass and higher velocities. In contrast, large tips are slow, but have a lot of mass, making them resistant to drag. So with that, a large tip will and can flow the same distance as a small tip.
Hello.... Kuh...need some help here. :)
FM1
You will need some kid's Play Doh in different colors and then one of the plastic play dough factory machines that use "EXTRUSION" to make long strings by pressing the dough through a shape using a piston type pressing mechanism. Soften 4 or more colors of dough and roll them until they are about the same diameter as the cylinder in the extrusion machine. (If your wife has an old time cake decorating cylinder with a screw piston it will work as well.) Cut some thin wafers about 1/2 inch thick from the rolled dough. Place the wafers in the extruder using your imagination for the color sequence. Select the largest round opening "die" that you have for your device, and press the dough through the device. Take your extruded snake and carefully cut it lengthwise to observe the pattern generated by the different colors. Your semicircular snake should show the first color of the extrusion toward the outside and the last one in the middle. This "coring" effect is one of the causes of the stream destruction. Any roughness on the inside of the die (nozzle) will cause a greater degree of coring and thus disrupt the pattern. The effect of coring doesn't stop when the stream leaves the nozzle, but continues as long as the stream is passing through the air.
Firemech's reference to mass is correct. The larger the diameter of the stream the greater the mass/circumference ratio. That is the same as saying cross sectional area compared with circumference, or there is less nozzle and air friction per gallon of water. Thinking about the effects of friction loss, you can come to a similar conclusion about friction loss vs diameter, because Hazen-Williams uses the conduit diameter to the 4.87 power in the bottom of the equation. Larger hose has less friction loss per gallon delivered.
Increasing nozzle pressure increases stream velocity, causing increased "friction loss", causing more rapid destruction of the stream. All this brings us back to the 1880's work of Imperically designing the first fire nozzles. By the way, the Play Doh experiment was suggested to me by an old boss in a carbon plant where I worked in the research department. Great illustration of what happens in an extrusion press.
Gotcha thanks, I knew i could find an explination on here. Basicly as i understand it. the stream has more mass so the air has less drag on the stream. this allows it to go farther through the air. Combined with the fact that the stream has more mass (water in it) the air has more to break up.
Quote:
Originally Posted by FIREMECH1
Do you need to keep the pressure constant or do you need to keep the volume constant? If you push 265 out of the 1" tip, flow velocity will be considerably higher and I can see the feathering/peeling of the stream begin to be significent. I think the variance between the 1" and the 1 1/8" would turn out greater then 1 1/8 and 1 1/4 as the incremental changes begin to become less significent. Would make for an interesting pump session.
You need to keep the pressure constant. Pressure is adjustable to any orifice size. However, the size of the orifice will only flow the volume that it can, no matter what the pressure is.
If you're looking into the hydraulics of flowing water to a distance, read the above.
FM1