Calibration of the QCH (or EQH) - Albumen Height Gauge is an important feature of using the instrument effectively and maintaining the accuracy to which it was originally calibrated.
With use the QCH (or EQH) Albumen Height Gauge probe can become worn which effectively will shorten slightly the length of the probe, when this happens readings of .0 mm will not be obtained on the flat surface of the QCAL or QCAP Glass breakout assessment Table, in fact no reading could show on the QCD, QCM+ or EQM read out screen and similarly a reading of the height of the calibration block as shown on the side of the calibration block may not show when the probe is placed on to the TSS QCH-CB 11mm calibration block.
Calibration check is advised on a daily basis, to maintain total accuracy normally no adjustment is required but if it is, the following procedure should be followed:
The QCH (or EQH) Albumen Height Gauge is calibrated on the QCD, QCM+ or EQM to which it is interfaced. This calibration is carried out by adjustment to the two potentiometers marked "FS and Zero" or "11.0 and 0.0" which can be seen as two fine screws through the QCD, QCM+ or EQM.
To enable calibration to be carried out switch on the QCM+ or EQM, Press the switch marked X or cancel on the QCM+ or EQM, or on later models the switch marked X, followed by pressing the Albumen Height selection switch, this should give the 12.5 figure on the QCM+ or EQM red LED screen in the Albumen Height mode with the display showing 12.5 press down the probe to the glass surface adjust the "Zero" potentiometer with the small screwdriver (supplied with the system), until you obtain a reading of 0mm, with no egg on the table the reading will not freeze and you will have to hold down the QCH (or EQH) Albumen Height Gauge probe whilst making the adjustments hold down the probe for you whilst adjustment is made to the two screw type potentiometer until it's made.
Then place the TSS calibration block under the pointed probe and hold down the probe onto the block and adjust the "FS" potentiometer until you get the EQM, QCM+ or QCD display reading the same as on the side of the TSS QCH-CB calibration block. Now recheck on the glass for zero (.0) and then again on the TSS calibration block till you are happy with these two readings.
Make fine adjustments again if required so that when the probe is on the glass it reads .0 and on the TSS calibration block reads it reads the same as on the side of the TSS calibration block.
If using a QCD then as a guide the reading at rest will between 17.5 - 19.9, push the QCH probe using the blue handle, down onto the glass and adjust to .0 then place the QCH-CB 11mm calibration on the glass and measure and then adjust to 11.0 then re-check the .0 reading and then again 11.0 as they will interact with each other until final measurement is made.
These two potentiometers are interact, this means changes to one affects adjustments made to the other and therefore fine tuning of each one alternatively may be necessary to obtain the correct settings.
Make sure you only handle the QCH by holding / touching only either RED handle (if used with a QCM+) or BLUE (if used with a QCD) plastic handle, otherwise you might freeze the device causing a false reading if you touch the QCH metalwork.