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Drift

Published: 2023-03-27      Revised: 2025-06-23

With the SpanBox5, there are three methods for drift: drift to phx calibration, drift to cylinder calibration, and VVA drift.

ProcessDescription
Drift to phx CalibrationThis type compares the phx calibration value for a given concentration. Pass/Fail is determined on the percent amount in the settings of the Drift positive or negative values.
Drift to Cylinder CalibrationThis type follows above Pass/Fail based on the known cylinder concentrations as the benchmark.
VVA DriftThis type uses cylinder concentrations and runs through three test samples for each one. Pass/Fail is based on the average for the three samples.
  1. Make sure the phx42 is ignited and warmed up before attaching it to the SpanBox5.
  2. Tap the Drift box on the Home screen.
  3. Follow the on-screen prompt to confirm the phx42 is attached to THE SAME PORT it was calibrated on earlier in the day.
    • Analyzers with a Daily Calibration from today will appear.
    • On the right of each analyzer, the latest EOD and Noon drift results will be shown.
  4. Check the boxes next to the analyzers to be drifted:
    • If the analyzer can't be discovered, it will be grayed out.
    • If the analyzer is in range, wait a minute for the SpanBox5 to discover and connect.
  5. Tap either Noon or End of Day radio button at the bottom of the screen.
  6. Tap Next.
    • Note: If a drift of the same type (Noon or EOD) has already been performed on a unit, it will prompt you to confirm you want the previous drift overwritten.
  7. If the cylinder information is correct, tap Next. This will auto-advance after 10 seconds. Otherwise, tap Manage Cylinders (you must use the same cylinders used for calibration).
    • The Drift process will begin.
    • Units will be drifted to the selected cylinders.
    • If you are running a standard drift, each gas will be applied once.
    • If you are running a VVa drift, each gas will be applied 3 times.
    • If a unit fails a gas, it will continue testing the unit while continuing the drift process for the other units.
  8. Select your name from the Technician dropdown and sign, then tap OK.
Standard Drift FormulaD = Drift reading; C = Calibration reading or cylinder concentration; Drift Pct = ((D – C)/C) x 100
VVa Drift FormulaDrift % = ((D – C) / C ) x 100 for each attempt of the drift and then for the overall Drift Pct for the gas; Drift Pct = (((D1+D2+D3) / 3) – C ) / C ) x 100
Drift to…Calibration PPM: Calculates the passing drift PPM using the confirmation PPM value from the analyzer's Daily Calibration. Cylinder Concentration: Calculates the passing drift PPM using the cylinder's Actual Concentration value. Both: Calculates the passing drift PPM using first the Calibration PPM and then separately the Cylinder Concentration and requires the drift PPM to pass both.