Metering Tip Calculator Instructions

The Metering Tip Calculator will determine the dilution ratio for each color of metering tip based on the actual water pressure supplied to the specific unit being installed.

Step-By-Step Instructions:

  1. Provide the Unit Flow Rate for the unit being installed
    • The Unit Flow Rate is a baseline value that is specific for each unit.
    • Refer to the Flow Rate Chart on Page 2 of the Installation & Operation Instructions.
    • Enter any of the GPM / PSI pairs into the Metering Tip Calculator as the Unit Flow Rate.  It does not matter which pair is used, they will all return the same results.
  2. Provide the Actual Water Pressure (PSI) at the unit
    • The Actual Pressure is the pressure of the water supply that is connected to the unit.
    • If the unit is equipped with gauges, read the water pressure gauge with water flowing through the complete unit.
    • Important:  Use the "running" water pressure.  Do not use the "static" pressure of a non-flowing water supply. The static pressure will read higher than the running water pressure and cause unexpected results.  To determine the running water pressure, read the gauge with the unit connected to the water supply and water flowing through the injector, hose, and discharge assembly provided with the unit.
    • If the unit is not equipped with gauges, use a Water Pressure Test Kit.
    • Alternately, consult a plumber to determine the running water pressure.
  3. Click "Calculate"
    • The results table will display the dilution ratio for each color of metering tip.
    • The results are shown in several formats. Hover over the column names to see definitions for each format.
    • Click "Scientific View" to see the math behind these calculations.

Tips & Tricks:

  1. Stronger dilution ratios can often be achieved using no metering tip at all (leave the tip holder empty).  Refer to the Metering Tip Chart on Page 2 of the Installation & Operation Instructions to see the “No Tip Ratio” for a specific unit or injector.
  2. To simulate a pressure washer, enter the flow rate in Gallons Per Minute for the pressure washer (ex. 4.5 GPM) and enter the pressure as 1000 PSI.  Then enter the actual pressure as 1000 PSI.  Change the GPM for different volume pressure washers and leave the pressure at 1000 PSI, regardless of the actual PSI of the pressure washer.  Please note that only units in our Pressure Washer Foamers & Sprayers Category are designed for use with pressure washers.  Dilution ratios may vary for discharge hoses over 50’.  The metering tip calculator will not specify the no-tip-ratio (the strongest ratio) - refer to unit instructions.
  3. The calculator cannot account for chemical viscosity (thickness). Thicker chemicals will draw slower than water thin chemicals, resulting in weaker ratios than shown in the chart.  A viscous chemical pickup assembly (#491404-A) is available for many units to help compensate for this effect.
  4. Read the Knowledge Center document Consistent Venturi Proportioning for more information about how to ensure consistent dilution ratios using Venturi equipment.
  5. Contact us for further assistance.
Lafferty Equipment Manufacturing, Inc.
5614 Oak Grove Road
North Little Rock, AR 72118
TFN: 1-800-999-2820

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