Power-Up & Verification

Author:Matthias Boularot
Created on:24 Feb 2026

Power-on sequence and self-test verification for the molbox terminal.

About this task

Perform this procedure at the start of each measurement session to verify that the molbox system is operating correctly before making flow measurements.

Procedure

  1. Push the power switch on the rear panel.
    The molbox initializes, performs error checks, calibrates its internal ohmic measurement system, and displays the main run screen. The top left of the screen should show a flow value near zero or <BPR HI>.
  2. Verify that the main run screen does not display <NO BLOC>.

    If <NO BLOC> is shown, the molbox has not detected a molbloc connection. Check that the molbloc electrical cable is properly connected and push SETUP, <1molbloc> to reload the molbloc data.

  3. Check the pressure measurement by connecting the molbloc to the molbox, shutting off the gas supply, and opening both molbloc ends to atmospheric pressure.
    1. Push P&T to display the pressure and temperature screen.
    2. Observe the upstream and downstream absolute pressures.
    3. Verify both readings indicate current atmospheric pressure and agree within ±0.02 % of the nominal full-scale calibrated range.
    Note:
    The pressure values on the P&T screen are corrected for TARE and AUTOZERO. If the readings disagree by more than the tolerance, one or both RPTs may need calibration or service.
  4. Check the temperature measurement.
    1. From the P&T screen, push P&T again to display the temperature screen.
    2. Verify that both molbloc PRT readings agree within ±0.2 °C and approximately match ambient temperature.

    Allow 30 to 60 minutes of warm-up in a stable temperature environment before evaluating temperature agreement. If the two readings disagree by more than ±0.2 °C, there may be a problem with the molbloc or the molbox TEMPERATURE MEASUREMENT function.

  5. Push ESCAPE to return to the main run screen.
  6. Perform a TARE at the operating line pressure before making measurements.

    Push TARE to zero the pressure transducers at the current line pressure. This removes offset errors from the pressure readings.

Results

The molbox is ready for flow measurements when all verification checks pass and the main run screen displays a flow value with the <*> Ready indicator.

CAUTION:
Set the security level to low with password protection to prevent inadvertent changes to critical internal settings. See the Fluke manual section on security levels.