Part 2 examines the effects that pump operators can expect from double and hookup tapped fire hydrants as well as the three major fire of heavy hydrant operations photo 1. Photos by author.
Video Highlights
The hydrant outlet area is only one part of the puzzle when attempting to maximize hydrant flows. It usually goes without saying that when connecting to the steamer port of the hydrant, the supply line of choice is large-diameter hose LDH photo 2. These same firefighters are often surprised when the available flow rate from the hydrant barely increases after connecting with medium-diameter hose.
When attempting to maximize hydrant flow rates, we must remember that fluids follow the path of least resistance. In this scenario, the operator will see a negligible increase in both the available water and residual intake pressure on the pumper photo 3.
Here, since we have attached a much larger supply line to the hydrant outlet, the outlet size of the hydrant becomes the limiting factor with regard to the available water, not the hoseline diameter. This means that more water can flow through the larger lines with less pressure loss. The result will be higher residual intake pressures at higher flow rates. As stated in Part 1, double tapping a fire hydrant is the single most effective way of maximizing the flow potential of a fire hydrant.
Each test began with a controlled flow through the steamer port only; then the side port was opened while the flow rate from the pumper remained the same. The reading on the flowmeter represented the flow rate through the side port alone. The results from these tests are listed in Tables 1 and 2.
A very interesting trend emerged after comparing these results. While this does not initially seem impressive, it is important to remember that hydrant flow rate through a hoseline has the biggest impact on the friction click within that line.
This was a huge revelation that explained why operators experience rises in residual intake pressures when opening the side port of a double tapped hydrant. The only time this did not occur was when the hydrant was double tapped with 4-inch supply line photo 6.
The key here is that to truly maximize the flow capability from a hydrant, the supply line connected to the hydrant must be larger than the outlets to which it is being connected. This truly makes the area of the outlet the limiting factor in the operation. Thus far, we have discussed the differences between residual main pressure and residual intake pressure, the effects of using multiple hydrant outlets, and the effects of supply line diameter on hydrant flow rates.
Now, let us examine what happens when we put all of these variables in play together. Table 3 outlines hydrant results of a series of flow tests conducted with the Crossville TN Fire Department. Prior to flowing any water during these tests, the static intake pressure was recorded at 80 psi.
Only a single 5-inch supply line connected to the steamer port was used during the first round of tests. The initial fire rate was set at gpm through the single line and was slowly brought up to 2, gpm while hydrant the pressure learn more here the hydrant and the residual intake pressures on the pumper.
Heavy Hydrant Hookups: Maximizing Hydrant Flows, Part 2
When the flow rate reached 2, gpm through the single 5-inch line off the steamer, the residual intake pressure at the pumper was measured at 25 psi and the pressure at the hydrant was measured at 52 psi. The difference of 27 psi was the result of the friction loss in the 5-inch supply line, the hydrant, and the intake plumbing of the engine.
The effects of double and triple tapped configurations were tested next. The increase in residual intake pressure means hydrant there is a significant reduction in friction loss within the system. This results in two major benefits to the operator:.
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However, when a single 5-inch line off the steamer port was used, the residual intake pressure was only online dating messaging psi.
By adding a second 5-inch line off the side click the following article of the hydrant, the residual intake pressure rose to 40 psi while the hydrant pressure remained at 52 hookup. The next test involved adding a third 5-inch supply line to the last hydrant port while the flow rate hookup anal at 2, gpm.
When this occurred, the residual intake pressure on the pumper rose from 40 psi fire 45 psi while the pressure at the hydrant remained at 52 psi. While a 5 psi increase in residual intake pressure seems hookup, it represents a Fire this test was performed, the flow rate was then increased to 2, gpm through both a double tapped and triple tapped hydrant configuration.
The results showed that at a flow rate of 2, gpm, the residual intake pressure at the pumper dropped to 25 psi when both double and triple tapped configurations were used. In both configurations, the pressure at the hydrant was recorded as 40 psi while 2, gpm was flowing.
The final test involved taking the flow rate up to 2, gpm through a triple tapped configuration. When the flow was increased to 2, gpm, the residual intake pressure on the pumper dropped to 15 psi and the pressure at the hydrant dropped to hookup psi photo 9. Therefore, we are still operating within the guidelines set forth by most municipal water authorities and the AWWA.
The only way the operator can make this assessment safely is with a gauge placed can olivia young hookup hotshot situation the hydrant.
When this tactic is used, the friction loss between the hydrant dating site for name the supply pumper is reduced tremendously. This results in higher residual intake pressures at the supply pumper, which provides three major advantages:. Fire Apparatus Magazine Pumpers. Says Gov. Ned Lamont ordered flags lowered to half-staff for a Wethersfield firefighter who died fighting a brush fire on Lamentation Mountain.
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