| 1. |
Preamble |
| 2. |
Scope |
| 3. |
User Industries requiring calibration of temperature measuring devices
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| 1. |
Preamble
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Temperature is the state, which determines the direction of flow of heat from one body to another. In other words temperature is the measure of hotness or coldness of a given body and the thermometer is the device to measure this. Temperature is not directly measurable by comparison with a standard, as in the case of length or mass. We can infer the temperature of a body by measuring
(i) length of mercury column in a capillary tube
(ii) the electric resistance of a platinium wire
(iii) the pressure of an ideal or non-ideal gas
(iv) the equilibrium pressure of a gas above a boiling liquid
(v) the thermoelectric emf between the dissimilar metals
(vi) the speed of a sound in a gas and
(vii) the magnetic susceptibility of a paramagnetic salt
The International Temperature Scale ITS-90 is the reference scale for the range of temperature. The practical implementation of ITS-90 requires the ability to transfer the scale from standard instruments to other secondary instruments either by comparison calibration or by using fixed points.
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| 2. |
Scope |
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Temperature measurement and calibration of temperature measuring devices/instruments in the over all range of –50 °C to 1200 °C
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2.1 Liquid filled glass thermometry: |
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Range : -50 °C to 300 °C |
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2.2 Thermocouple thermometry |
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Range: 0 °C to 1200 °C |
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Accuracy: ±0.5 ºC to 1 ºC |
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| 2.1. |
Liquid filled glass thermometry: |
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| 2.1(a). |
Items which need to be calibrated for most industrial needs, their range and accuracy of temperature measurement:
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| Sl. No. |
Item |
Range (mm) |
Accuracy |
| 1. |
Liquid-in-glass thermometer |
-50 °C to 300 °C |
± 5 °C to 1 °C |
| (i) |
Industrial (Hg) mercury and
Alcohol glass thermometers |
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| (ii) |
Low range thermocouples |
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| (iii) |
Digital thermometers with
thermocouple sensors or RTD |
-50 °C to 1200 °C |
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| (iv) |
Dial gauge (analogue)
thermometers with bi-metal sensors |
--50 °C to 300 °C |
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| (v) |
Liquid calibration bath |
--50 °C to 300 °C |
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| 2. |
Thermocouples R, S and K type |
-50 °C to 1600 °C |
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| (i) |
Type S & R thermocouples |
-0 – 1600 °C |
± 1 °C to 3 °C (Pt/Pt 50% Rh and |
| (ii) |
Type K thermocouples |
-0 – 1200 °C |
Cr, Al alloys |
| 3. |
T, C Indicators |
-50 °C to 1200 °C |
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| 4. |
Resistance, Temperature devices RTDs |
-50 °C to 600 °C |
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| 2.2. |
Standards/Instruments required for laboratory: |
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| 2.2(a). |
Liquid filled glass thermometry: |
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| (a) |
Standards: |
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| Sl. No. |
Item |
Range |
Resolution |
Quantity |
Approximate cost
(Rs. in lakh) |
| 1 |
Glass thermometers |
--50°C to 20 °C |
0.1 °C |
1 |
0.02 |
| 2 |
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0°C to 25°C |
0.05 °C |
1 |
0.05 |
| 3 |
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25°C to 50°C |
0.05 °C |
1 |
0.05 |
| 4 |
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50°C to 75 °C |
0.05 °C |
1 |
0.05 |
| 5 |
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75°C to 100 °C |
0.05 °C |
1 |
0.05 |
| 6 |
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100°C to 200 °C in span of 10°C |
0.02 °C |
1 0 |
0.50 |
| 7 |
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100°C to 200 °C in span of 25°C |
0.05 °C |
4 |
0.12 |
| 8 |
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200°C to 300 °C in span of 50°C |
0.1 °C |
2 |
0.06 |
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| (b) |
Constant Temperature Source: |
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| Sl. No. |
Item |
Range (mm) |
Stability |
Approximate Cost (Rs. in lakh) |
| 1 |
Ice point cell |
0.000 °C |
± 0.005 °C |
0.10 |
| 2 |
Low Temperature bath |
-50°C to 100°C |
± 0.005 °C |
6.00 |
| 3 |
Water bathl |
20°C to 95°C |
± 0.002 °C |
6.50 |
| 4 |
Oil bathl |
50°C to 300°C |
± 0.005 °C |
7.50 |
| 5 |
Fluidized bath |
300°C to 600°C |
± 0.10 °C |
15.00 |
| 6 |
Dry Block calibrator |
50°C to 600°C |
± 0.10 °C |
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| (c) |
Medium for constant temperature source: |
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| Sl. No. |
Item |
Range (mm) |
Stability |
Approximate Cost (Rs. in lakh) |
| 1 |
Alcohol for low temperature bath |
-80°C to 20°C |
25 litres |
0.20 |
| 2 |
Distilled water for water bath |
-5°C to 95°C |
25 litres |
-- |
| 3 |
Silicon oil for Oil bath |
-50°C to 300°C |
25 litres |
3.00 |
| 4 |
Aluminium Powder for fluidized bath |
100°C to 600°C |
20 kg |
0.20 |
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| (d) |
Accessories required: |
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| Sl. No. |
Item |
Quantity |
Approximate Cost (Rs. in lakh) |
| 1 |
Reading telescope for measurement in calibration of glass thermometers, magnification not lesser than 10 X |
1 |
0.30 |
| 2 |
Exhaust Chimney |
1 set |
0.50 |
| 3 |
Cub boards, almirahs |
as required |
0.20 |
| 4 |
Computer, printer, UPS and other peripherals |
as required |
1.00 |
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| (e) |
Manpower required: |
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| Metrologist/ Head |
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M Sc/ BE/ B Tech degree in
Physics or in any branch of
Engineering |
ONE |
| Technical officer |
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Diploma in Mechanical/
Instrumentation engineering |
TWO |
| Technician |
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B Sc with some experience in
measurement and calibration |
ONE |
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| 2.2(b). |
Thermocouple thermometry: |
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| 2.2(b-1) |
Standards required: |
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| Sl. No. |
Item |
Range |
Resolution |
Quantity |
ApproximateCost (Rs. in lakh) |
| 1 |
Type ‘S’ Thermocouple |
0°C to 1200 °C |
0.1 °C |
1 |
2.50 |
| 2 |
Type ‘S’ Thermocouple |
0°C to 1200 °C |
0.1 °C |
1 |
2.50 |
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| 2.2(b-2) |
Constant temperature source and measuring device: |
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| Sl. No. |
Item |
Range |
Resolution |
Stability |
ApproximateCost (Rs. in lakh) |
| 1 |
Ice Point cell |
0.000 °C |
-- |
±0.005 °C |
0.10 |
| 2 |
Annealing Furnace |
1200°C |
-- |
±2 °C |
10.00 |
| 3 |
High temperature tubular furnace |
100°C to 1200°C |
-- |
±0.5°C |
16.00 |
| 4 |
61/2 Digit Voltmeter |
0 to 50 mV |
0.1 μV
or 1 μV |
±0.5°C |
5.00 |
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| 2.2(b-3) |
Accessories required: |
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| Sl. No. |
Item |
Quantity |
Approximate cost (Rs. in lakh) |
| 1 |
High temperature insulating material (fiber fax or kawool) |
1 kg |
0.50 |
| 2 |
Exhaust chimney |
1 set |
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| 3 |
Almirah for storage |
as required |
0.20 |
| 4 |
Computer, printer, UPS and other peripherals |
1 set |
1.00 |
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| 2.2(b-4) |
Manpower required: |
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| Metrologist/ Head |
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M Sc/ BE/ B Tech degree in
Physics or in any branch of
Engineering |
ONE |
| Technical officer |
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Diploma in Mechanical/
Instrumentation engineering |
TWO |
| Technician |
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B Sc with some experience in
measurement and calibration |
ONE |
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| 3. |
User Industries requiring calibration of temperature measuring devices: |
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- Petrochemicals and petroleum products
- Oil refining
- Plastics
- Iron and Steel
- Metallurgical related
- Cement manufacturing
- Food Research Institute
- Automobile
- Aerospace
- Textile
- Electrical and Electronics
- Thermal power plants
- Heavy and medium engineering
- Medical laboratories and hospitals
- Temperature instrument manufacturer
- Oceanographic studies
- Pollution boards
- Fluid flow measurements
- Defense laboratories
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