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NOTIFICATION FOR CHOOSING PROPER SENSOR

ERROR BY LACK OF INSERT LENGTH

A precise measurement is not possible unless the temperature of a measured object and a measuring junction for a thermocouple and an RTD element for an RTD become the same temperature. Generally, temperature goes down to outward the sensor by heat conduction because the measuring part is inserted a protection tube. A insert length is different by a different condition. The chart below shows necessary insert lengths by multiplying a outer diameter of protection tube.


NECESSARY INSERT LENGTH FOR PRECISE MEASUREMENT
TYPE STILL LIQUID STILL ATMOSPHERE
RTD (MI sheath) MORE THAN 10 TIMES MORE THAN 15 TIMES
RTD (protection tube) MORE THAN 10 TIMES MORE THAN 15 TIMES
T/C (metal)   MORE THAN 15 TO 20 TIMES
T/C (ceramic)   MORE THAN 15 TO 20 TIMES


CASE STUDY FOR SENSOR SET UP

1. CASE E -45
Lack of the insert length, the volum of the boss is too large, and no thermal insulation on the pipe.


2. CASE A -15
Lack of the insert length, the volum of the boss is too large, and lack of thermal insulation on the pipe.


3. CASE B -2
Good boss installation, but no thermal insulation on the flange.


4. CASE C -1
The installation is good, but a little lack of insert length.


5. CASE D 0
The best way for the installation.



RESPONSE SPEED

It takes some time for an element and a measuring junction being the same temperature as an object. It is called "temporal error." A smaller diameter responds faster, but mechanically weaker. It is important to choose a sensor by the purpose and necessity.
Please refer to each technical data for response time.

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