PIC Tut 9 (Temp)

The bulbs of a filled thermal system thermometer are usually made up of

• A)Glass
• (B)Plastic
• (C)Copper
• (D)stainless steel

Which of the following is true about thermal filled system?

• (A)not so rugged
• (B)Need electric power
• (C)Need frequent maintenance
• (D)A large bulb is necessary for sensitivity

Ambient temperature effect refers to

• (A)inability of sensors to detect small temperature changes
• (B)errors in reading due to changes in surrounding temperature.
• (C)Changes in process fluid properties due to temperature changes
• (D)errors in reading due to the high temperature damage to sensors

What’s the working principle of Thermocouple?

• (A)Pressure of material changing with temperature.
• (B) balancing pressure acting on medium.
• (C) Emf produced by 2 dissimilar metals corresponds to temperature differences.
• (D) Resistance of metal corresponds to temperature change.

Thermocouples are often chosen because of

• (A)Will not be affected by other electrical devices.
• (B)Useful for a very specific temperature range
• (C) Resistance to Corrosion
• (D) High accuracy

The temperature sensor that sends out resistance (ohm) signal is

• a)  Pyrometer.
• b) Thermocouple.
• c)  Filled thermal system.
• d) Resistance Temperature Detector

The electrical resistance of a RTD

• a)    increase with increasing temperature
• b)   decrease with increasing temperature
• c)    fluctuated with increasing temperature
• d) does not affected by temperature

The purpose of having a third wire in a RTD is

• a)    to measure resistance.
• b)    to compensate for ambient temperature effects.
• c)    to extend the length of the cable.
• d) To improve the sensitivity of the RTD

Optical pyrometer indicate temperature by

• expanding
• matching colour/brightness of filameter
• softening and changing shape
• changing resistance

A temperature measuring device suitable for measuring very high temperature is

• thermocouple
• thermal filled system
• resistance temperature detector
• pyrometer