Instrumentation Interview Question : Pressure measurement

Interview Q & A Instrumentation
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Q)What is pressure ? or Define pressure ?

A)Pressure is the amount of force applied over a defined area.

Q)The factors that will influence hydro static pressure ?

A)Level of the liquid Density of the liquid Pressure on the surface of the liquid (vapor space)

Q) Density of liquid

A)Density is the mass of a particular substance per unit of volume

Q) Definition of Specific Gravity

A)Specific gravity is the ratio of the density of a particular liquid to the density of water at a reference temperature.

Q)Reason for measuring pressure ?

A)Safety Process efficiency Cost savings Inferred measurement of other variables

Q)Three measurable pressure

A)Head (hydrostatic) pressure Static (line) pressure Vapour pressure

Q)Pressure-measurement devices can be categorised according to the reference pressure

A)Absolute Gauge Differential

Q) Different type liquid column pressure gauges

A) Barometer  Manometer

Q)What are the basic parts of Mechanical pressure gauges ?

A)Sensing device Mechanical dial or indicator

Q)Most commonly used pressure sensing device?

A)Bourdon tube  Bellows and capsules

Q)What is pneumatic controller ?

A) A pneumatic controller is a device that, in response to an input pressure, sends a pneumatic output to a relay

Q)What is pneumatic transmitter ?

A)A pneumatic transmitter is a device that, in response to input pressure, outputs a proportionate, standardized pneumatic signal.

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A pneumatic transmitter is a type of measuring instrument that converts a physical parameter, such as pressure, temperature, or flow rate, into a proportional pneumatic signal. The pneumatic signal is typically a pressurized air signal, which is then transmitted to a control system, such as a pneumatic controller or a PLC (Programmable Logic Controller).

Pneumatic transmitters are widely used in process industries, such as oil and gas, chemical, and food and beverage, for monitoring and controlling various process parameters. They are known for their reliability, durability, and simplicity of operation.

In a pneumatic transmitter, the physical parameter to be measured is sensed by a sensing element, such as a pressure sensor or a temperature sensor. The sensing element then generates a proportional pneumatic signal, which is amplified and conditioned by the transmitter’s electronics. The amplified pneumatic signal is then transmitted to the control system through a pneumatic tubing or a compressed air line.

Pneumatic transmitters are still used today, although they are being replaced by digital and electronic transmitters in many applications. However, pneumatic transmitters remain a reliable and cost-effective option for certain process applications, particularly those in hazardous environments where electronic instruments may not be suitable.

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Sure, I can help you with that! Here are some common interview questions related to pressure measurement instrumentation:

  1. What is pressure? Pressure is the force exerted per unit area by a fluid or gas on a surface. It is typically measured in units of pounds per square inch (psi), pascals ¶, or bar.

  2. What are the different types of pressure measurement instruments?

There are several types of pressure measurement instruments, including mechanical gauges, transducers, and transmitters. Mechanical gauges measure pressure using a mechanical mechanism, such as a Bourdon tube or diaphragm. Transducers convert pressure into an electrical signal, while transmitters amplify and transmit the signal to a remote monitoring device.

  1. How do you calibrate a pressure transmitter?

Calibrating a pressure transmitter typically involves applying a known pressure to the device and comparing the output signal to the expected value. This can be done using a handheld calibrator or a dedicated calibration rig.

  1. What is the difference between gauge pressure and absolute pressure?

Gauge pressure is the pressure relative to atmospheric pressure, while absolute pressure is the total pressure including atmospheric pressure. Gauge pressure is typically used for measuring the pressure of a fluid or gas within a closed system, while absolute pressure is used for applications such as vacuum measurement.

  1. What are some common sources of measurement error in pressure measurement instrumentation? Measurement errors in pressure measurement instrumentation can be caused by a variety of factors, including temperature changes, sensor drift, mechanical wear, and fluid density changes. These errors can be minimized through regular calibration and maintenance of the instrumentation.