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email:
tijit@singnet.com.sg |
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Temperature Calibration |
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Temperature Calibration
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A very important part of the portable tank gauging tape is
the temperature reading, and its accuracy. The TANKTECH Portable System uses
a 3-wire PRT or Platinum Resistance Thermometer, which is linear and has
standard and stable output all the time. A
Thermal heated water bath is used, the temperature controller of this water
bath has precision PID control mode, giving a minimal deviation of ±0.01șC.
Operating temperature range -40șC to +120șC. There is a circulating pump
with a capacity of 10 l/min at maximum pressure of 145mbar. |
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The TECHNE TE-10D has a PRT
thermometer, and the indicator has been calibrated against a National
Standard probe with error of less than 0.01șC.
An external reference thermometer
is used to compare this temperature with the Portable Probe reading. This is
the high accuracy Palm Thermometer Probe, with Traceable Accuracy to ±0.05șC
or better. It has resolution to 0.01șC or F, and plugs into the Palm without
boxes or Modules.
Temperature readings were taken
progressively at increments of 5șC from the cold temperature to the highest
point of the cargo in the tank for Chemical and Product carriers, without
any adjustments done. |
The Palm Thermometer |
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The readings were recorded with the error readings at each
individual point. After it reaches the maximum point, and stabalised for 5
minutes, adjustments are done on the zero and gain of the Analog amplifier
inside the probe to achieve a minimum offset reading for the high and low
points. For consistent deviations, the zero resistor is adjusted to correct
this constant deviation, and for a widening or narrowing deviation, the gain
or span resistor is adjusted.
The TFC is a complete digital system on a split architecture,
it has two micro-controllers, one at the sensor probe, and one at the
display panel. They communicate with each other through the tape conductor
bus, and the analogue part of the temperature measurement is inside the
probe. Therefore it is only possible to calibrate the probe without the
display to get the correct temperature reading. |
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It is not possible to calibrate
the sensor probe without a liquid thermal bath. All calibrations done has a
certificate of calibration to go along with the Service Report.
Temperature calibration is a tedious chore, and time
consuming. Therefore most Calibration companies charges high price for such
task. Tijit Pte Ltd
invested into buying the calibration equipment with the best performance and
best control with PID (Proportional, Integral and Derivative) Actions. |
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