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2-piece adjustable smooth bore nozzle
Part #1; Nozzle Bail with pistol grip assembly
Bail controls nylon ball valve within the bail assembly which controls the flow of water.
Part #2; Nozzle body with adjustable rubber bezel
The nozzle body houses a nylon cone shape stream straightener which is permanently mounted in the base of the nozzle body. The top portion of the nozzle body is adjustable to control the various orifice sizes. It can be adjusted at the top of the nozzle body (rubber bezel) or at the base of the nozzle body (raised round portion).
Part #1 Nozzle Bail with Pistol Grip Assembly Part #2 Nozzle Body with Adjustable Rubber Bezel
The nozzle body and bail are constructed of what I believe is a lightweight pyro-lite material and a large rubber bezel at its tip for easy operation with a gloved hand. The bail handle is a dropped forge one piece steel handle attached with steel roll pins. With the bail in the open position the nozzle is exactly 12” in length (1 foot) I do not know its weight but my approximate guess is about 8lbs. My overall impression is that it is a lightweight easy to use firefighting nozzle but we were able to reveal some flaws in the mechanics and the concept of this style adjustable smooth bore nozzle explained on the next page. I believe with some tweaking this could be a very effective and sought after nozzle in the firefighting industry. Attached are pictures and videos of the issues we encountered. I thank you for this opportunity and hope this information is of some assistance.
Adjustable smooth bore concept flaws:
With all of the research and data that is available to the fire service today the smooth bore nozzle has seen a resurgence in its popularity and usefulness. This is mostly do too the many challenges of the modern fire ground. Fire departments are seeing how important it is to have a solid stream of water that has the penetration, reach and higher GPM flow at reduced reaction forces to combat today’s unpredictable fires with reduced manpower.
Several Nozzle manufacturers have introduced adjustable smooth bore nozzles or combination fog and smooth bore nozzles into the market place with mixed reviews. The advantage that you are supposed to gain with adjustable tip size over traditional smooth bore nozzles is that you don’t have to shut the nozzle down (stop flowing water) and remove or add a different size tip to increase your GPM flow.
Many of these adjustable nozzles change tip size by opening or closing the bail. This has created a behavioral concern because for years firefighters are taught in their basic training to fully open or close the bail for safe operations. Now firefighters utilizing these adjustable smooth bore nozzles are taught to only open the nozzle to the tip size or GPM flow that is needed. The fact that your nozzle still allows firefighters to operate the bail the way we have been taught for years is an advantage in your design which I like very much.
My overall concern with the adjustable smooth bore concept is the issue of the pressure which these lines are pumped at to achieve correct GPM flow. The nozzle pressure is a constant 50psi for all smooth bores operated as hand lines and 80psi for master streams the challenge becomes communication between the nozzle firefighter and the pump operator when the tip size is adjusted due to the wide range of friction loss versus GPM.
5/8’s tip flows 81GPM at 6psi of friction loss per 100 feet of 1 ¾ inch hose.
11/16’s tip flows 99GPM at 14psi of friction loss per 100 feet of 1 ¾ inch hose, more than double of 5/8’s.
¾ tip flows 118GPM at 20psi of friction loss per 100 feet of 1 ¾ inch hose.
7/8’s tip flows 160GPM at 35psi of friction loss per 100 feet of 1 ¾ inch hose.
15/16’s tip flows 180GPM at 50psi of friction loss per 100 feet of 1 ¾ inch hose.
1” tip flows 209GPM at 60psi of friction loss per 100 feet of 1 ¾ inch hose.
Calculating Engine Pump Pressure (EPP) for the flow range found on the VSB Nozzle;
Each attack line is 200 feet of 1 ¾ hose; 5/8’s tip=EPP of 62psi to achieve 81GPM
11/16’s tip=EPP of 78psi to achieve 99GPM
¾ tip=EPP of 90psi to achieve 118GPM
SAFE and Effective flow range
7/8’s tip=EPP of 120psi to achieve 160GPM
15/16’s tip=EPP of 150psi to achieve 180GPM
1” tip=EPP of 170psi to achieve 209GPM
The flow range is too wide to ensure the proper Engine Pump Pressure is achieved to maintain a safe GPM flow. A smooth bore nozzle which is under or over pressurized will not provide a safe and effective stream placing the operator in danger. If the nozzle firefighter adjusts the tip size without making the engine pump operator aware or if the tip size is adjusted accidentally in the heat of the fire fight disastrous results could happen! I was also concerned about the ability for the nozzle firefighter to be able to see or verify which tip size the nozzle is set on in fire and smoke conditions.
Adjustable smooth bore mechanical flaws:
We discovered a few flaws with how easily the tip size could be adjusted when not flowing water and while advancing the nozzle. The large raised section of the nozzle body and the rubber bezel were very sensitive to anything it came in contact with while simulating the advancement of an attack line.
• I blindfolded three of my firefighters and placed the nozzle (attached to a 200 foot charged 1 ¾ inch attack hose) in their hands and asked them to simulate advancing the attack line while not flowing water through the nozzle.
• Each time the nozzle came in contact with a piece of furniture, doorway, the floor or the firefighter’s gloved hand it would move the adjustable bezel moving freely through the adjustable tip sizes without the firefighter knowing it was doing so.(I have attached a small video documenting its sensitivity)
• The adjustable section of the nozzle body needs some type of positive locking device at each tip size so that the nozzle firefighter will have to deliberately move it and be able to feel it “click” through the tip size adjustments, much like the GPM settings in an adjustable gallonage fog nozzle.
• We encountered no problems with the adjustable nozzle body while flowing water. It worked as designed.
I was also concerned with the sensitivity of the bail handle. We were able to get the bail to shut itself off without touching the handle on numerous occasions.
• We began to flow water and lightly tapped the pistol grip handle on the ground and the bail shut off half way drastically reducing our flow. (Video attached.)
• We were also able to shut the bail off by whipping the nozzle around in a rapid motion like we would do in heavy fire conditions. We were able to repeat this several times very easily. (Video attached)
• We were also able to get it to shut off just by lightly touching the bail handle.
Adjustable smooth bore positive aspects;
I have extensive experience in fire conditions with a smoothbore nozzle and I have to admit this nozzle produced a very efficient and effective stream.
• It has superior penetration and reach!
• The stream maintained its shape, mass and velocity for close to 50 feet before it broke apart!
• Its flow settings are accurate! We verified this with a flow meter and Pitot tube and gauge!
• Its compact size and lightweight features make it easy to operate.
• There are only 2 moving parts, the bezel and the bail, less chance of mechanical failure.
• There is no maintenance required that I am aware of.
Captian Bryan T Smith @ FirefighterToolbox.com