README.md

In dCraigJones/n185: Graphic functions for Fire-Flow Testing

n185

Overview

Creates n1.85 logarithmic graphs based on NFPA 291 recommendations. Additional verbs, such as tilt() and shift(), are provided to aid analysis, in addition to common utility functions, such as aff() to calculate available fireflow at 20 PSI.

Installation

install.packages("devtools")
devtools::install_github("dCraigJones/n185")

Usage

Typical usage is to create a blank graph template using the n185() command, then add fireflow objects to the graph template with the draw() command. Fireflow objects are defined by specifying the fireflow test results with the ff().

For example,

# Fireflow test results defined as
# Static, Test Flow, Test Residual
a <- ff(60, 3000, 20)

# Create a blank graph template
n185()

# Add the fireflow object to the template
draw(a)

The n185_ui() function simplifies fireflow plots with a graphical interface that can: - create fireflow objects, - define graphical parameters (such as color and line type) - specify graph information, such as title and date - automatically populate legend at a user-defined location - refine x-axis and y-axis boundary - export to clipboard or save by right-clicking the graphic

Utility Functions

aff()

Available Fireflow calculates the flow at the minimum allowable pressure (typically 20 PSI) using the fireflow object.

# Define a fireflow object and the available fire flow
a <- ff(60, 3000, 20)
aff(a)

# Default minimum allowable pressure is 20 PSI
# However, other pressures can be defined.
aff(a, 35)

nff()

Needed Fireflow calculated the minimum allowable pressure for the required fireflow. It is useful when checking the available pressure at the connection point (or supply curve) of fireflow calcuations.

# Define a fireflow object
a <- ff(60, 3000, 20)

# Required fireflow must be specified
nff(a, 1500)

kp()

Defines the unit friction slope per linear foot of pipeline in PSI. It provides a general function to calculate Hazen-Williams headloss for arbitrary pipe lengths.

# Friction slope in 1 miles (5280 ft) of 12-inch pipe
k <- 5280*kp(12)

# Corresponding Headloss at 2000 GPM
k*2000^1.85

# default friction factor (C value) is 130
# other values can be passed to the function
k <- 5280*kp(12, 100)
k*2000^1.85

Verbs

tilt()

Tilt is used with kp() when translating fireflow test results to a location further downstream.

# intitialize n185 graph template
n185()

# define fireflow object and draw to graph template
a <- ff(60, 3000, 20)
draw(a)

# calculate friciton factor to downstream location
k <- 5280*kp(12)
b <- tilt(a, k)

# draw new fireflow
draw(b, "grey50", 2)

shift()

Shift is used to translate fireflow results to a different static condition. It is used to correct for changes in elevation or to account to variations in static pressure.

# intitialize n185 graph template
n185()

# define fireflow object and draw to graph template
a <- ff(60, 3000, 20)
draw(a)

# translate fireflow to a new static condition
b <- shift(a, 40)

# draw new fireflow
draw(b, "grey50", 2)

Example Workflow

Assumed that two field tests are conducted on the same water main.

The first test is on Hydrant Asset ID FH-1523. The second test is 3,218 LF downstream on the same 12-inch water main at Hydrant Asset ID FH-1680.

# Create Graph Template with User-Defined axis
n185(5000, 60)

# Create Fireflow Object from field tests
a <- ff(58, 2731, 35, "Asset FH-1523")
b <- ff(53, 1243, 43, "Asset FH-1680")

# Graph fireflow results
draw(a, "blue")
draw(b, "grey15")

The model results and field test can be confirmed by adding the headloss from 3,218 LF of 12-inch pipeline and adjusting for elevation differences

# Translate Fireflow from FH-1523 to the location of FH-1680
# (asterisk notates modified fireflow)
k <- 3218*kp(12)            # Calculate friction slope
a_12 <- tilt(a, k)          # Add headloss
a_12 <- shift(a_12, 54)     # Adjust for Elevation

# Graph Results
draw(a_12, "blue", 2)

Based on the engineer's fireflow calculations 35 PSI at 2,000 GPM is required at FH-1680. Back-out the headloss from 12-inch pipe and re-apply using a 16-inch

# Check available pressure at Needed Fire Flow
nff(b, 2000)

# Remove headloss from 12-inch piping
a_16 <- tilt(b, -k)

# Add headloss from 16-inch piping
k <- 3218*kp(16)
a_16 <- tilt(a_16, k)

# Check available pressure at Needed Fire Flow
nff(a_16, 2000)

# Graph Results
draw(a_16, "grey15", 2)

# Draw a point to highlight the fireflow supply point
pt(2000,,a_16, "grey15")

Fireflow objects are stored with the draw() and n185() commands. They can be displayed on a legend by draw_legend() command. Other information can be added to the graph using BASE graphics, such as title and abline.

# Automatically add legend to the graph
# default position in "topright"
draw_legend()

# Add a title
title("Fireflow Test Results")

# Add contact info
title(sub="For more information contact: [e-mail]")

# Draw a line to indicated the minimum allowable pressure
abline(h=20, col="red")

dCraigJones/n185 documentation built on Feb. 1, 2020, 2:09 a.m.