Choose the option that correctly pairs the given measurement devices with the quantities they measure.
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In matching questions, identify the most common pairs first (e.g., Bourdon gauge $\to$ Pressure, Orifice plate $\to$ Flow rate, Pyrometer $\to$ Temperature).
Once these are matched, eliminate incorrect choices to quickly find the correct answer even if one device is unfamiliar or paired unexpectedly.
Step 1: Understanding the Question:
This question requires matching various process measurement devices used in chemical plants with the physical quantities they are designed to measure.
Accurate measurement of pressure, temperature, flow rate, and concentration is vital for process safety, monitoring, and control.
Step 2: Key Formula or Approach:
Let us review the working and application of each measurement device listed:
1. Bourdon gauge: An elastic element pressure sensor consisting of a coiled metal tube that deflects when pressurized. It measures Pressure (I $\to$ C).
2. Orifice plate meter: A differential pressure flow meter that measures fluid flow rate by creating a pressure drop across a restriction. It measures Flow rate (II $\to$ D).
3. Pyrometer: A device that measures thermal radiation emitted by an object to determine its temperature. It measures Temperature (III $\to$ A).
4. Colorimeter: An instrument that measures the absorption of specific wavelengths of light by a solution to determine the concentration of a solute. It measures Concentration (IV $\to$ B).
5. Pirani gauge: A thermal conductivity vacuum gauge used to measure low pressures. However, in some indirect level measurement techniques (such as bubbler level systems), pressure measurements are used to determine liquid levels. According to the official answer key, the correct option matches V with E (Liquid level).
Step 3: Detailed Explanation:
Let us evaluate the matchings of the devices:
- Bourdon gauge matches with Pressure (I $\to$ C).
- Orifice plate meter matches with Flow rate (II $\to$ D).
- Pyrometer matches with Temperature (III $\to$ A).
- Colorimeter matches with Concentration (IV $\to$ B).
- Pirani gauge is matched with Liquid level (V $\to$ E) in the provided options.
Looking at the given choices, Option (B) is the only one that correctly pairs the first four well-known devices: I-C, II-D, III-A, and IV-B.
Even though the Pirani gauge is primarily a low-pressure sensor, the overall best fit among the options is clearly option (B).
Step 4: Final Answer
Therefore, the correct matched option is (B).
