Circular chart recorder calibration - temperature pen calibration


#1

Zero adjustments:

The pen trace can be optimally altered by turning the pen arm friction onto the pen arm as shown in figure below:

Turn the screw gently in a clockwise direction to bolden the pen trace, turn the screw gently in an anti-clockwise direction.

Turn the pen arm fine zero to adjust the screw in the direction required to move the pen to the desired amount to position the pen to read accurately at zero when pressure is vented or any desired known pressure value on the chart.

Temperature pen calibration:

Mechanical calibration is concerned with the precise setting of the zero, span and linearity of the recording pen compared to a known temperature read with a certified thermometer traceable to national calibration standards.

  • Allow the recorder to stabilize at a low temperature just above the minimum scale with the measuring element.

  • The temperature recording pen should read within ±1% of full span at the correct temperature value.

  • If necessary, adjust pen fine zero adjust the screw to bring the pen to the correct reading.

  • If the pen reading is more than 5 angular degrees, adjust the pen fine zero screws to bring the pen arm in line with the pen bracket and loosen the coarse zero adjustment screw holding the compensator arm to the bourdon tube centre temperature.

  • Allow the recorder to stabilise with the measuring element in high temperature just under scale maximum.

  • The temperature recording pen should read within ±1% of full span at the correct temperature value.

  • If necessary, adjust the pen reading by moving the link connecting the compensator arm to the ratio post on the mechanism pen bracket.

  • To move the link, loosen slightly the counter nut of the ratio post and raising the pivot will increase the movement of the boom while lowering the pivot will decrease the movement of the boom. Re-tighten the lock nut after adjustment.

  • Repeat all the above steps until no further adjustment is necessary.

  • Allow the recorder to stabilise with the measuring element in temperature equal to the middle of chart span.