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9210 Calibration with TPW cell

Manual Calibration Procedure:

 

Note: The use of a 1560 with a 2562 thermometer and a 5614, 5626, 5628 probe or equivalent ¼” probe is recommended for testing.

 

Use the back right block well for the 9210 probe whenever possible to calibrate the 9210

 

  1. ¼” 5628 probe, or equivalent, is to be placed in the 1 o-clock position using a 3110-4, “C” insert. An “A” or “B” inserts may also be used.
  2. Choose four set points to use in the calibration of R0, ALPHA, DELTA, parameters. These set points are generally C, 2 C, 60.0 C, and 120.0 C but other set points may be used if desired or necessary.
  3. Set unit to lowest set point. When unit reaches set point and display is stable, wait 20-30 minutes and then take a sample from thermometer. Sample the set-point resistance by holding down the SET key and pressing the DOWN key.
  4. Repeat step 2 for the other three set points.
  5. Using the recorded data, calculate new values for R0, ALPHA, DELTA, and BETA parameters using equations given below:

 

Compute Delta:

 

A = T3 – T2

B = T2 – T1

C = [T3 / 100][1-(T3 / 100)] - [T2 / 100][1-(T2 / 100)]

D = [T2 / 100][1-(T2 / 100)] - [T1 / 100][1-(T1 / 100)]

E = R3 – R2

F = R2 – R1

delta = [AF - BE] / [DE - CF]

 

T1 and R1 are the measured temperature and resistance at 2.00 C

T2 and R2 are the measured temperature and resistance at 60.00 C

T3 and R3 are the measured temperature and resistance at 120.00 C

 

Compute R0 & ALPHA:

 

a1 = T1 + delta[T1 / 100][1-(T1 / 100)]

a3 = T3 + delta[T3 / 100][1-(T3 / 100)]

rzero = [R3a1 – R1a3] / [a1-a3]

alpha = [R1 – R3] / [R3a1 – R1a3]

 

T1 and R1 are the measured temperature and resistance at 2.00 C

T3 and R3 are the measured temperature and resistance at 120.00 C

delta is the new value of DELTA computed above

 

  1. Program new values into unit.

 

TPW (triple point of water) calibration:

 

  1. After the 9210 calibration is accomplished, place a foam washer into the block then place the mini-TPW cell into the center well of 9210 apparatus. Fill ethanol alcohol into the well, and the cell should be covered by alcohol. Add the top insulate disk above the cell.
  2. Use “program” mode to realize the TPW automatically. The 9210 “program” modes are melt, freeze, and maintain. Set the 9210 to “Freeze” mode, and the cell temperature will be decreased to -4.5°C. The beeper will remind you for next step, after the temperature reaches -5°C and after a few minutes stabilization. If nobody takes action in 1 minute after the beeper starts, the 9210 mode will change from “freeze” to “melt” to protect the cell from breaking.
  3. Take the cell out from the 9210 using a tool. The water in the cell should still be under supercool. Shake the cell slightly, left to right. The water will start to freeze immediately, and the ice will spread through the whole cell. Put the cell back into the 9210 apparatus, and add the top insulate disk.
  4. Set the 9210 apparatus to “Maintain” mode. The temperature of the cell will maintain at 0.01°C.
  5. The 9210 is ready to be calibrated at the water triple point.
  6. In order to properly maintain the triple point of water cell the accuracy of the 9210 near the triple point (0.01°C) must be very precise, within 0.02°C or better. The 9210 may need to be calibrated periodically to ensure this accuracy. The Cal TPOS function is used for this purpose. It allows one to calibrate the control probe in reference to the triple point of water. The TPW cell must be in its partially frozen triple-point state. During calibration the control probe is removed from the block and inserted into the TPW cell. TPOS is then adjusted until the display shows exactly 0.01°C. While the control probe is in the TPW cell, the controller is unable to use it to control the temperature. For this reason, while in the TPOS calibration mode active control is suspended and the controller simply outputs constant power to the heater. The calibration must be done fairly quickly, in less than five minutes, or the block temperature may drift excessively.

 

The TPOS calibration proceeds as follows.

 

6.1          Get into the Secondary Menu by pressing SET and EXIT together.

6.2          The unit will now display the heater power. Example:   56P   Press EXIT three times.

6.3          At “Config?” press SET.

6.4          “Oper” will now be displayed. Press UP three times.

6.4          The unit now displays the "CAL?" prompting. Press SET five times.

6.5          Press SET to continue or EXIT to skip the R0, Alpha, and Delta.   

6.6          Press SET until you reach TPOS

6.7          The unit displays the control probe temperature while maintaining constant power to the heaters.

6.8          Remove the control probe from the block and place it in the TPW cell. Wait for the temperature to stabilize (one to two minutes).

6.9          Use the UP and DOWN buttons to raise or lower the TPOS until the probe temperature reaches 0.010°C.

6.10        Now return the control probe to its position in the block. Wait one minute for its temperature to stabilize then press SET to complete the procedure.

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