Sorry, could not find start water group. My department did an extensive study of 1-3/4 hose for over a year. We used differant brands of hose, automatic nozzles, constant gallonage nozzles and alot of research from differant archives on this matter. We found that the target flow for 1-3/4 hose should be 150-180 g.p.m. Anything over 180 has to much back pressure and is a major safety concern. The flow of 150 is easy to control and the stream has a good punch to the fire. We use the Elkhart 4000-18, 150 g.p.m @ 50 psi nozzle pressure.
200 ft. of 1-3/4 had pump discharge pressure of 120 to 130 depending on the flow you want.
There are several good articles on 1-3/4 hose in the Fire Engineering archives.
I target 150-200 gpm for initial attack. This dependant on which nozzle comes off the truck first. Pump pressure of 150psi, elkhart sm30f (not my first choice automatics scare me but that is what we are given) prefer smooth bore lower nozzle reaction, more water and no chance of a fog stream applied accidentaly.
150 gpm sounds reasonable, but there are nozzles availablt today that can deliver upwards of 220 gpm and more, both smooth bore and combination types for 1 3/4 inch hose. This size by the way is probably to best compromise between 1 1/2 inch and 2 1/2 inch, although you do have the option of 2 inch. The pro's and con's are nearly endless, but my experiences with 1 3/4 inch have proven very satisfactory.
Back in the 1970's, there were at lest two depts that used 3M "RAPID WATER', an additive. They were FDNY and my dept, Syracuse NY. Any fire service history buff out there will tell you we were known (at that time) as the "Buck Rogers Fire Dept" because of the many innovations that the chief was willing to try and experiment with. Anyway, we found that a 1 3/4" line with TFT nozzle (another Tool first used in Syracuse) and Rapid Water gave flows comparable to a 2 1/2" line. We have stuck with that combination on all preconnects even though Rapid Water is no longer made. We pump at 200 psi and shoot for 200 gpm.
Simply put, water volume puts out 100 year old balloon frame dwellings better than anything else. We have no shortage of water and we use it. BTW- we are the ONLY ISO Class One in New York State.
I'm not sure if the cylinder of a soap-like substance we put into an "around the pump" type tube on the pump panels of our Barton American pumpers in the Riva, MD VFD was 3M's "RAPID WATER" or from some other supplier, but it DID work quite similarly to the 3M product. I first saw the setup when I joined that department in 1958 and it was called "wet water". E-1 was a 1949 International 500 gpm and E-2 another International 500 gpm fitted with a 1000 gal. tank on a dual rear axle chassis.
As I recall from my years in the USAF, the "wet water" concept disappeared some time in the mid 60's, only to be "re-invented" some time in the 1990`s as Class A foam. Sound familiar? Your phylosophy is oh so true; put enough of that wet stuff on the hot stuff and it should go out, before floating away.
Just recently we concluded a 4 month evaluation concerning our current nozzles which are Elkhart SM20, and 30 (automatic nozzles) which require 100 psi nozzle pressure. we found out through this process that in nearly every case, these nozzles were being under pressurized, therefore very little flow was being attained. In most cases the flows that were being generated were around 100 gpms. Based on PDP the pump panels ranged from 120 psi to 130 max and that was only if there was a gorilla at the end of it, and even then if the pump operator did set his pump panel at a higher psi, such as 150psi, the guy at the end of the nozzle was gating down the bail on the nozzle. Why was this? Everyone that was asked about this replied the same, the nozzle reaction was kicking their butts. Based on fireground hydraulics at 120 psi PDP we know right away that the nozzle demands 100 psi, so that leaves a huge 20 psi to account for friction loss. With my department utilizing 1 3/4" hose at 200 ft. that tells me, that those lines have less than 100 gpms going though it. But I tell you what those streams coming from those nozzles sure look pretty "weak" ! The other part of this evaluation was determining how can we fix this, and it was decided lets look into the low pressure constant gallonage nozzles. So we set out to detemine what nozzle pressure would best suit us, 50 psi, or 75 psi. We looked at nozzle reaction, reach, quality, and ease of fireground calculations, and any issues with that caused problems with our hose, ie kinking. After testing both pressures we decided upon the 150 gpm @ 50 psi nozzle worked well for us. We then tested 3 nozzles, from TFT, Elkhart, and Akron, this eval went on for 3 months. 2 of the 3 nozzles recieved great reviews from the field members. And both nozzles had positive features, that were liked, so right now in this part the game we are waiting for bids to be submitted from both distributors to make final decision on who to go with. So the bottom line is for our 1 3/4" preconnects we decided that the 150 @ 50 is our best choice. If the fire demands more based on NFF we go straight for the 2 1/2.
We are using a dual force nozzle target flow of 175gpm w/ 50 psi at the tip in the standard setting it is kept in (low pressure). This flow is in the middle of the manufacturers range so we have some top end room. All that said we do have preconnected 2 1/2 of course.......and excellent plugs....
We at Little Rock F.D. did a year long study on hose, espically 1-3/4. After researching the FE archives, we found a lot of information on flows and flow testing. We bought a flowmeter and contacted as many nozzle manufactures as we could find. We tested around 15 differant nozzles from smoothbore to fog. We found that 1-3/4 was safe up to the flow of 180 gallon per minute. The pressure is managable and safe with reasonable nozzle reaction. We purchased the Elkhart 4000-14. It has a 15/16 smoothbore and a fog tip rated at 150 gpm at 50 psi nozzle pressure. Anything over 150 tp 160 flow needed we go to a 2-1/2 with smoothbore tip of 1-1/8 inch.
Our target flowrate is 150 gpm from 200' x 1 3/4" line and Elkhart 4000-18 (I think) 175@75 nozzles. We've found that 150 gpm flow rate through this combination of equipment gives us a good combination of knockdown with the fuel loads we typically find in our area (rural residential) while maintaining ease of movement and control.
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