Look at this month's article in Fire Chief on smoothbore v. combo/fog.
Thought y'all might like this.
"Gold jacket, green jacket, who gives a ****?"
Just give me water.
Theusje: Sorry about not replying promptly to your post.
I agree that your pump operators are under pumping at 4 to 6 bar. Your description includes the term “Water Thief” that in the states describes an appliance with one inlet (female) and three gated outlets (male) two 1 ½” and one 2 ½”.
Assuming you are talking about the same device, the proper pump pressures for a 120 ft. leader of 70mm line into the thief and then 120 ft. attack lines coming out of the thief as follows:
One 1 ¾” line with a 475 lpm nozzle needs a pump pressure of 115 psi (7.8 bar).
Placing the second 1 ¾” line in service (250 gpm total) needs about 128 psi (8.75 bar)
Assuming that you will then attach 120 ft. of 70 mm hose with a larger nozzle and double the application rate (500 + gpm), the pump pressure should be raised to nearly 11 bar (160 psi) This would compare favorably to a 2 ½” smooth bore of 1” diameter or 2.5 cm. (280 gpm)
Expect to need 3 firefighters to handle this at a reaction force of 130 pounds. It would have a good reach of about 88 ft before it began to separate and be susceptible to winds or fire drafts.
Thanks for the reply Kuh Shise.
When using a waterthief we rarely attach more then two 1 ¾” lines onto it, atleast for interior fire fighting. Most of the times one line is enough, but it's good to know that addding that second line doesn't raise the pump pressure too much.
We have another setup we use in high rises (10 floors max):
180 feet of 2 ¾” hose and 240 feet of 1 ¾” hose
We should be able to reach the 4th or 5th with the 2 ¾” hose, then place a waterthief and start using the 1 ¾” hose. To do this we have hose 2 ¾” hose folded in the engine in a kind of hosebed and folded into cassettes. The 1 ¾” hose is folded into cassettes and in bundles.
The next video shows an example, I'm sorry for the music used:
This is a real old thread, but I thought I would bring it back to life. There are a number of new comers that haven't seen these type of nozzles put to use.
Back a number of years ago, I was a volunteer member of a full time department. We were having a number of structure fires that were taking too long to put out. I arrived at one 2 story structure that was really roaring. The engine had already set up the deck gun with a combo nozzle and was putting it into the right front window on the first story. It wasn't having much effect.
Several other members showed up and we pulled off a 1.75 hand line and I put a straight tip on the hose. Turned on the flow and shot the water into the left front window. The room went dark in about 30 seconds. Moved over to the right front window and did our thing again even with the deck gun still flowing water into the same window. Again the room went dark in about 30 seconds.
The junior members just stood there in amazement. How come a hand line can do a better job than a large deck gun putting out the fire was their question. Even the fire chief had to see it to believe it. He was watching from the front corner of the property as this was taking place.
We had a meeting with the members that were at the structure fire the following evening. The chief started asking how many had seen the difference that the hand line with the straight tip nozzle had on the heavy volume fire.
To make a long story short, the chief changed the way the department was attacking heavy volume fires from that time forward. We always had one handline on the crosslay with a straight tip nozzle from that time. The department trained to pull the straight tip nozzles on any heavy working fire.
After a while the state fire marshal started asking how we were able to stop a number of the fires that he was investigating. We told him we went back to the old days when they didn't have all these fancy combo nozzles. We were using the straight tip nozzles on the heavy fires we encountered. He was impressed and started talking with other departments he covered and asked them their tactics on fighting heavy involvement. If we were able to knock down fires so fast and used much less water, then maybe there just was something to the smooth bore nozzles.
You might just want to look into going back to the way out grandfathers did things. They didn't have access to the fancy combo nozzles. All they had was smooth bore back then. You might even find it does make a difference in how fast you can knock down a heavy seated fire.
I'm confused. Was the deck gun in a fog position?
The facts are 200 gpm in a straight stream from my low pressure combo nozzle will extinguish the same amount of fire as a 200 gpm stream from a smooth bore tip. Well, assuming of course both hit the fire.
Conclusion? The solid stream held together enough to resist the wind, the straight stream from the automatic nozzle being hollow couldn't do it. All of our master streams now carry stacked tip nozzles.
I suspect jim202's deck gun was not being used to it's greatest ability. The high nozzle position may have dictated an angle for the stream that just did not allow it to do the job. But the handline being operated from the ground and up close allowed the stream to hit the ceiling of fire room(s), allowing fire to darken down.
Golly guys, I said the same thing above...:D
I wish someone would make adouble stack nozzle that was a 7/8 inch tip on top of a 1 inch tip. Added to out 1 1/4 inch slug tip this would be perfect for our 2 inch hose.
It would give us a good 1 3/4 inch flow of 160 gpm, then bump us to 209, and then take us to 300 at 42 psi at the tip.
I like those numbers.