ICE OT EXAM 1

EMF

It is important that thermocouples are standard so that the same will always represent the same temperature.

Bourdon Tube

Is a hollow tube with an elliptical cross section used to determine pressure.

-40°C

Mercury solidifies at this temperature.

Hall Voltage

Is a function of the current density, magnetic field, charge density, and carrier mobility of the conductor.

Mechanical

Type of force sensor usually involving some form of spring such as in a simple spring balance or bathroom scale.

Differential Pressure

Type of flow meter that converts flow rate into differential pressure.

Optical

Type used to measure the output speed of a rotating object with the use of a light-sensitive cell and light beam.

Piston Type

Usually used in hydraulics where the ability to withstand shock, vibration, and sudden pressure changes is needed.

Accelerometers

Are widely used to measure tilt, inertial forces, shock, and vibration.

Turbine Rotor

Has an axial rotor which is made to spin by the fluid and the speed represents the flow.

Thermocouples

Are used to determine temperature using two wires with dissimilar electrical properties joined at both ends, with one junction hot and the other cold.

Ultrasonic Level

Uses sound waves from the surface and determines the depth from the time taken to receive the reflected sounds.

Pressure Gauge

Works on the principle that depth is proportional to pressure.

Air Pressure

Uses air through the liquid and the pressure of the air is related to the depth.

None

Contains two transducers, one on each side of the pipeline.

Piezo Electric

Is a type of electrical pressure transducer wherein a piece of crystalline material produces an electric charge on its surface when mechanically stressed.

Rotameter

Uses a float inside a tapered tube. The restriction causes a pressure drop over the float and the pressure forces the float upward.

4 to 20 mA

Standard signal range used by most modern analogue equipment.

Pneumatic

Signals commonly used in process industries for safety especially when there is a risk of fire or explosion.

Tachometers

Are built into electric motors or coupled to a rotating body to measure their speed.

Pellets

Are used in applications where extended heating periods are involved or when oxidation of a workpiece might obscure a marking.

Humidity

Can cause the measurement of air temperature to be misread when it is high.

Broadband Pyrometer

Uses a lens system or sight tube that detects radiation onto a blackened reference surface inside the instrument.

Thermopile

Consists of several thermocouples connected in series to provide greater sensitivity to small changes in temperature.

Doppler

Effect used by ultrasonic flowmeters in the propagation of sound through liquid.

Electromagnetic

Is a transducer that converts the volumetric flow rate of a conductive substance into voltage.

Sight Glass

Is a transparent tube connected to the side of a vessel.

Hydrostatic Head

Operates on the principle that any column of material exerts a force at the bottom of the column due to its weight.

Optical Pyrometer

Infers temperature by measuring thermal energy radiated from the surface using a viewfinder to observe the target and filament of a light bulb simultaneously.

Labels

Have one or more heat-sensitive indicators sealed under transparent heat-resistant windows.

Meshing Rotor

Type that consists of two rotors with lobes. When fluid is forced in, the rotors turn and operate the indicating system.

Purge Method

Method of determining level using a dip-tube vertically immersed in the fluid of a tank with an open end placed close to the bottom.

LVDT

Uses a magnetic core that slides in the tube and is attached to the mechanism being monitored with a non-magnetic stem.

Magnetic Pick-Ups

Use an inductive coil placed near the rotating body. A small magnet on the body generates a pulse every time it passes the coil.

Strain Gauge

In force sensors, a typical load cell consists of a metal cylinder with this fixed to it.

5 to 20

Recommended number of pipeline diameters downstream from an obstruction where the measuring device should be placed.

Paddle Wheel

Uses motion to measure the level of either granular or powdered solid material.

Capacitive

Are used for continuous level measurement.

Vortex Flowmeters

Use a blunt unstreamlined object such as a bar or strut placed in the flow path of the fluid.

Square Root Extractor

Produces a signal that will double if the flow rate doubles.

Custody Transfer

Flow measurement used to determine how much of a product is passed from the supplier to the customer.

Static Head

Force developed at the bottom of the tank due to the depth and density of the fluid.

Vacuum

Performs work by creating a pressure differential between the airtight surfaces of the equipment.

Pyrometers

Require the target being measured to completely fill the view of the instrument.

Temperature

A basic sensor is made by winding a thin resistance wire into a small sensor head.

Nickel

Is the most sensitive metal because it provides the greatest change of resistance for a given unit of temperature change.

PTC

Describes the condition where the resistance of electrically conductive metals varies directly with temperature.

Bellows

Is made of several capsules which are hollow flattened structures made from thin metal plate.

Rotameter

Is a variation of the differential pressure flowmeter and is also known as a variable area flowmeter.

Resolvers

Are available in brushless form that employs a transformer to couple the rotor signals from the stator to the rotor.