Pressure Thermometer

Pressure Thermometer Working principle,types, application, advantage & Limitations

1. Mechanical Measurement and Control System PRESSURE THERMOMETER Name –Deepak Kumar ID- 2015UME1075 Batch-M1

2. Objectives : Introduction Working Principle Construction &working Applications Advantages Limitations References

3. Introduction : A device used to measure temperature by measuring pressure exerted by a given volume of gas or liquid. It is one of the most economical ,versatile and widely used devices in industrial temperature measurement.

4. Working Principle : These thermometers work on the principle of thermal expansion of the fluid with the change in temperature is to be measured. Temperature change can be determined using these thermometers, which rely on pressure measurement

5. Construction : A pressure thermometer comprises of  Bulb    Flexible capillary tube Bourdon tube Linkage and gearing mechanism Pointer and scale arrangement

6. Bourdon Tube

7. Video : How pressure gauge works!!

8. Classification: Depending upon the type of Fluid Filled in the Bulb 1. Liquid pressure thermometer 2.Constant volume Gas thermometer 3.Liquid – Vapour thermometer

9. Liquid Pressure Thermometer : Usually Mercury is used as liquid Principle of working: expansion of liquid due to an increase in the pressure in a given volume Range :-30°C to 550°C

10. Constant Volume Gas Thermometer : Inert Gas(usually Nitrogen )is used in place of Mercury. Principle of working: According to ideal gas law PV = mRT   For constant volume P α T Temperature Range: -130 ° C to +540°C .

11. Vapor Pressure Thermometer : Liquid and vapour of the same liquid(liquid – vapour interface in the bulb) The liquid- vapour system does not have any error as it follows Dalton’s laws of partial pressure which states that if both liquid and vapour are present there is only one saturation pressure corresponding to a given temperature. Range : - up to 100°C.

12. Applications : Industrial equipments, piping Boilers, compressors Automobile dash board Muscle microcalorimetry

13. Advantages : Fundamental Simplicity Direct reading or recording Less expensive Stable in Operation and have a Good Accuracy(+1 or-1 °C) More Sensitive &Responsive(Deliver a high-speed response) Distance measurement Easy Maintenance

14. Limitations : Limited linearity and prone to errors. The bulb size may be too large to fit the available space. The maximum temperature is more limited than that in some electrical measuring systems. Proper Calibration of bulb,Capillary tube and Bouden tube is needed. If bulb is raised by a hight h from the calibration elevation ,then the Bourden gauge experiences an increse in pressure equal to Error= (density). g.h

15. References: https://www.youtube.com/watch?v=BIef-w0MkY0&t=8s https://www.youtube.com/watch?v=f9MJAXhLSv0&t=174s http://youtube.com/watch?v=yALTyExeS8M https://www.ncbi.nlm.nih.gov/pubmed/22254362 http://www.instrumentationtoday.com/filled-system-temperature-measurement/2011/ ENGINEEING METROLOGY & MEASUREMENT BY RAGHAVENDRA &KRISHNAMURTHY INSTRUMENTATION MEASUREMENT &ANALYSIS BY NAKRA &CHAUDHRY 9