# Pressure Measurement Interview Questions & Answers Part-1

## Q.1 What are the types of pressure?

• Absolute Pressure
• Gauge Pressure
• Vacuum Pressure

### Q.2 What is the difference between absolute pressure, gauge pressure, and vacuum pressure?

• Absolute Pressure: The reference of absolute pressure is a perfect vacuum.
• Gauge Pressure: The reference of gauge pressure is atmospheric pressure.
• Vacuum Pressure: Vacuum pressure is a pressure below atmospheric pressure.

• Kg/cm2
• PSI
• Pascal
• mmH2O
• mmWC
• Bar

### Q.4 What is the relationship between different pressure units?

• 1 atmospheric pressure = 14.6956 psi = 760 torr
• 1 bar = 750.0623 torr = 0.98696 atm = 100000 pascal
• 1 pascal = 10 dyne/cm2
• 1 kg/cm2 = 14.696 psi = 10,000 mmH2O

### Q.5 Which pressure type is the sum of the other two pressure types?

Absolute pressure is the sum of the vacuum pressure and gauge pressure.

### Q.6 What is a manometer and how does it work?

The manometer is a type of differential pressure measuring instrument. The manometer has a U-tube filled with liquid. The two ends of the tube are connected to a pipe or pressure tapings. Due to the difference in pressure, there is a difference in height of the liquid in both legs.

• Ring gauge
• Bell gauge

• Bourdon tube
• Bellows
• Diaphragm
• Capsules

### Q.10 Which is more sensitive to pressure bourdon tube, bellow or diaphragm?

• The diaphragm is most sensitive to pressure changes. Then comes bellow and then bourdon tube.

### Q.11 What is LVDT?

• LVDT stands for Linear Variable Differential Transformer. The primary and secondary winding of a transformer is kept constant. At the same time, the core of the transformer is connected to a pressure measuring end. When there is a change in pressure, the core moves accordingly. Due to the movement of the core, there is a change in voltage which is proportional to the pressure.

### Q.12  What is a strain gauge?

• A strain gauge is a type of resistive element. Whenever pressure is applied to the strain gauge element, the shape of the strain gauge changes. This changes the resistance of the strain gauge element. Thus, the pressure applied to the strain gauge creates a resistance change that is proportional to the applied pressure.

### Q.14 What are measuring devices used in industries?

• Pressure gauge
• Manometer
• Resistance type pressure measurement
• Inductive type pressure measurement
• Capacitive type pressure measurement
• Piezoelectric type pressure measurement
• McLeod gauge
• Thermal conductivity gauge
• Ionization gauge

### Q.15 What is the most common type of pressure measuring device?

• Capacitive type pressure transmitter is the most common type of pressure measuring device used in industries

### Q.16 What other quantities can be measured by the pressure transmitter?

• Level and flow can be measured using the pressure transmitter. For this purpose, a differential type pressure transmitter is needed.

### Q.17 How is level measured using a differential pressure transmitter?

• For measuring the level of a tank, 2 tapings are needed from the tank. One taping is taken from the bottom and one other taping is taken from the bottom. Both tapings are connected to the differential pressure transmitter. Tapping taken from the bottom is connected to the high-pressure side of the transmitter. Taping taken from the top of the tank is connected to the low-pressure side of the transmitter. According to the differential pressure, the tank level is known from it.

### Q.19 How is flow measured using a differential pressure transmitter?

• For measuring the flow of any fluid flowing through any pipe, 2 tapings are needed from the pipe. One differential pressure generating element like an orifice or venturi is used to generate a differential pressure across itself. One taping is taken from the upstream of the differential pressure generating device. While the other taping is taken from downstream of the differential pressure generating device. Both the tapings are connected to the differential pressure transmitter. Tapping taken from the upstream is connected to the high-pressure side of the transmitter. While taping taken from the downstream is connected to the low-pressure side of the transmitter. According to the differential pressure, flow is calculated. The relationship between the pressure and the flow is not linear. For this, a square root function is used in the transmitter to know the flow rate.

### Q.20 Is there any other factor taken into consideration while measuring the flow of gas using the differential pressure transmitter?

• Temperature compensation is needed for measuring the gas flow. Hence temperature measurement is done for the same.

The above pressure measurement interview questions and answers are generally asked in interviews, tests, and viva.