# Page 148 - WaterSense at Work

4-54
October 2012
4.11
Wash-Down Sprayers
Water Use After Retrofit
To estimate the water use after retrofitting an existing wash-down sprayer with a
nozzle, use Equation 4-24, substituting the flow rate of the retrofit nozzle. Self-closing
nozzles often flow at a rate of 7.0 gpm.
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Water Savings
To calculate the water savings that can be achieved from retrofitting an existing
wash-down sprayer with a nozzle, identify the following information and use Equa-
tion 4-25:
••
Current water use as calculated using Equation 4-24.
••
Water use after retrofit as calculated using Equation 4-24.
Equation 4-25. Water Savings FromWash-Down Sprayer Retrofit or Replacement
(
gallons per year)
=Water Use of Wash-Down Sprayer –Water Use After Retrofit or
Replacement
Where:
••
Current Water Use of Wash-Down Sprayer (gallons per year)
••
Water Use After Retrofit or Replacement (gallons per year)
Payback
To calculate the simple payback from the water savings associated with the wash-
down sprayer retrofit, consider the equipment and installation cost of the retrofit
self-closing nozzle, the water savings as calculated using Equation 4-25, and the
facility-specific cost of water and wastewater. Self-closing nozzles typically cost \$100.
Wash-Down Sprayer Replacement
A pressure washer or water broom typically uses 2.0 gpm, while heavy-duty hoses
can deliver higher flow rates from 9.0 to 20.0 gpm.
73
Current Water Use
To estimate the current water use of an existing wash-down sprayer, use Equation
4-24.
72
FSTC,
op. cit.
73
EPA and DOE’s ENERGY STAR,
op. cit.