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The Hydraulics 4 Jakes (H4J) pump operator's
system offers a simple, comprehensive approach
to calculating fireground hydraulics. The International
Fire Service Training Association's (IFSTA) friction
loss equation is the firefighter's benchmark for
pump proficiency. H4J is based on the IFSTA formulaic
approach to pump operations and correlates remarkably
well with what would be derived using the IFSTA
friction loss equation, C × Q² ×
L, where C is the coefficient of friction, Q is
the flow in gallons per minute divided by 100,
and L is hose length divided by 100. The H4J system
provides a simple and reliable tool that will
provide accurate fireground hydraulic calculations.
There is a limited range of fire service nozzle
sizes, required flow rates, and standard nozzle
pressures (SNP). A nozzle operated at the SNP
will produce a reasonably predictable quantity
of water. H4J uses this general nozzle flow rate
predictability to provide sequential, tactically
relevant flow rates. H4J's rounded flow rates
do not represent the exact quantity of water flowing
at any point within the evolution; they are based
on anticipated SNP nozzle flow rates and their
supply. The system enhances firefighter confidence
in operating integrated hose configurations and
achieves a flow rate very near the desired nozzle
requirement or supply need.
The H4J flow rates are based on standard stated
fog nozzle flow requirements and the solid stream
IFSTA equation 29.7 × D² × square
root of NP. The IFSTA solid-stream equation was
used with the various tip sizes operated at the
SNP and the results were simply rounded, providing
anticipated nozzle requirements that are tactically
relevant and easy to remember.
As a distribution device's flow rate is achieved
within any size hose, the hose will have a reasonably
predictable resistance to the water flowing within
it, known as friction loss (FL). The friction
loss calculation method used by H4J is universally
applicable to the different sizes and categories
of hose. The underlying variations in the flow
capabilities of different hose sizes allows H4J
to offer a simple universal friction loss number
sequence that is used to operate multiple sizes
of hose. The universal H4J friction loss number
sequence identifies the corresponding flow rate's
rounded friction loss per 100 feet in a specific
size hose at the provided H4J flow rate. The H4J
friction loss number sequence will provide near
benchmark hydraulic calculations for the four
sizes of medium diameter hose (MDH) and large
diameter hose (2 1/2-, three-, four-, and five-inch).
The two sizes of attack hose (1 1/2- and 1 3/4-inch)
share another easy-to-remember friction loss number
sequence.
H4J will provide flow rates for every industry
standard nozzle's SNP flow requirement and the
combined requirements of multiple nozzles operating
simultaneously. The H4J attack hose flow rates
are nozzle-requirement specific. The combined
flows of dual attack lines supplied by MDH are
reflected in H4J's MDH flows. All single-line
MDH nozzle flow rates are identified. Flows for
dual and tri-line MDH supplying a master stream
or appliance are easily determined by selecting
a tip size/nozzle flow/supply need and applying
equally divided flow rates. Operating in between
the H4J flow rates is obvious, and the two sizes
of MDH offer 18 different gpm flows to meet the
multiple nozzle/supply needs of the fireground.
H4J will operate single, dual, wyed, and multiple-line
configurations. The H4J flow rates are rounded,
sequential, hose category integrated, and operationally
significant.
Virtually every flow rate incorporated into
the H4J system has a tactical application and
some flow rates offer single, dual, and multiple-line
operational options. The firefighter correlates
the nozzle requirement and simply adds the rounded
friction loss number by the length of the hose
evolution.
H4J uses the firefighter's hand as a reference
point (Figure 1). Place the left hand forward,
thumb to the left. The numbers at the base of
each finger are rounded, sequential, and operationally
significant nozzle/supply oriented flow rates.
At the top of each finger is the H4J universal
friction loss number sequence. The sequential
H4J flow rates will have an associated friction
loss, which is easily identified by correlating
the universal friction loss sequence with the
desired flow.
View the 2 1/2-inch hose flow rates used by
H4J and identify the handline nozzle applications
of 200, 250, 300, and 350 gpm. Supplying a master
stream device with dual 2 1/2-inch lines is easily
accomplished with the H4J flow rates of 250, 300,
400, or 500 gpm. The H4J MDH flow rates will also
accomplish any dual attack/MDH nozzle combination.
Multiple line strategies are easily accomplished
with equally divided flow rates. The firefighter
must correlate the nozzle requirement with the
predetermined flow rates and universal friction
loss number sequence used by H4J. The system will
be accurate to the IFSTA equation, and is designed
to be simple, fast, and globally fireground comprehensive.
Example: 200-foot, 2 1/2-inch hose; 350-gpm fog
nozzle; and SNP of 100 psi.
IFSTA: 2 × 3.5 × 3.5 ×2 = 49
49 + 100 = 149 psi
H4J: 25 + 25 + 100 = 150 psi
Figure 1. Hydraulics 4 Jakes System
Jeff Welle is a career paramedic, firefighter,
and registered nurse. E-mail: info@hydraulics4jakes.com.
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