A device that converts a reading from a sensor or transducer into a standard signal and transmits that signal to a monitor or controller.A device that converts a reading from a sensor or transducer into a standard signal and

transmits that signal to a monitor or controller.

(a)  

Signals produced by changing the air pressure in a

signal pipe in proportion to the measured change in a process variable. The

common industry standard pneumatic signal range is 3–15 psig.

(a)  

The most common standard electrical signal is the 4–20

mA current signal. With this signal, a transmitter sends a small current through a

set of wires. The current signal is a kind of gauge in which 4 mA represents the

lowest possible measurement, or zero, and 20 mA represents the highest possible

measurement.

(a)  

Discrete levels or values that are combined in specific

ways to represent process variables and also carry other information, such as

diagnostic information. The methodology used to combine the digital signals is

referred to as protocol (Foundation fieldbus,HART, Profibus)

(a)  

A device that receives data from a measurement instrument, compares that data to a programmed setpoint, and, if necessary, signals a control element to take corrective action. Local controllers are usually one of the three types: pneumatic, electronic or programmable. Controllers also commonly reside in a digital control system.A device that receives data from a measurement instrument, compares that data to a programmed setpoint, and, if necessary, signals a control element to take corrective action. Local controllers are usually one of the three types: pneumatic, electronic or programmable. Controllers also commonly reside in a digital control system.

(a)  

A test during which known values of measurand are applied to the

transducer and corresponding output readings are recorded under specified

conditions.

(a)  

The region between the limits within which a

quantity is measured, received or transmitted, expressed by stating the lower and

upper range values.

(a)  

Lower end of the range.

(a)  

Defined as the algebraic difference between the upper and lower range

values.

(a)  

Capability of the instrument.

(a)  

The ratio of the error to the full scale output or the ratio of the error

to the output, expressed in percent span or percent reading, respectively.

(a)  

Permissible deviation from a specified value; may be expressed in

measurement units, percent of span, or percent of reading.

(a)  

The property of a result of a measurement whereby it can be related to appropriate standards, generally national or international standards, through an unbroken chain of comparisons.the property of a result of a measurement whereby it can be related to appropriate standards, generally national or international standards, through an unbroken chain of comparisons.

(a)  

Algebraic difference between the indication and the actual value of the

measured variable.

(a)  

(a)  

(a)  

(a)  

(a)  

Used to implement one or more safety instrumented

functions. An SIS is composed of any combination of sensor (s), logic

solver (s), and final elements(s). designed to prevent or mitigate hazardous

events by taking a process to a safe state when predetermined conditions

are violated. Other common terms used are safety interlock systems,

emergency shutdown systems (ESD), and safety shutdown systems (SSD).

(a)  

Is a safety function with a specified

Safety Integrity Level (SIL) that is implemented by the SIS to achieve or

maintain a safe state. A SIF’s sensors, logic solver and final elements act

together to detect a hazard and bring the process to a safe state.

(a)  

A measure of safety system performance, in terms of probability of failure

on demand (PFD). This convention was chosen based on the numbers: it is

easier to express the probability of failure rather than that of proper

performance (e.g., 1 in 100,000 vs. 99,999 in 100,000).

(a)  

Refers to a set of processes and practices which aim to ensure the

continuous and efficient operation of machinery, and equipment.v

(a)  

All actions necessary for retaining an item, or restoring to it, a serviceable condition, include servicing, repair, modification, overhaul, inspection and condition verification.

(a)  

Attempt to maximize performance of production equipment efficiently and regularly

(a)  

implies that repairs are made after the equipment is failed and can not perform its normal function anymore

(a)  

is a stitch-in-time procedure and incorporates

(a)  

Principle – “Prevention is better than cure”

(a)  

machinery conditions are periodically monitored and this enables the maintenance crews to take timely actions, such as machine adjustment, repair or overhaul

(a)  

inability to produce work in appropriate manner

(a)  

the inability to meet the specified performance standard

(a)  

a physical condition which indicates that the failure process has started

(a)  

Failure is not apparent until the function is attempted

(a)  

is force divided by the area over which that force is applied

(a)  

The pressure due to the weight of the atmosphere above the point where it is measured

(a)  

Actual height of a column of liquid. A container or vessel can be any shape, but head is only determined by the height of the liquid

(a)  

The pressure due to the head of a liquid column. Frequently, this is referred to as pressure head. Pressure is independent of the shape of the container and depends only on the properties of the fluid and the height.

(a)  

law stating that the pressure applied to a confined static fluid is transmitted with equal intensity throughout the fluid

(a)  

Pressure measured with a perfect vacuum as the zero point of the scale

(a)  

Pressure measured with atmospheric pressure as the zero point of the scale

(a)  

Pressure less than atmospheric pressure measured with atmospheric pressure as the zero point of the scale.

(a)  

Difference in pressure between two measurement points in a process

(a)  

a pressure decrease that occurs due to friction or obstructions as an enclosed fluid flows from one point in a process to another.

(a)  

Device for measuring pressure with a liquid-filled tube.

(a)  

Clear tube bent into the shape of an elongated letter U

(a)  

A manometer with a reservoir serving as one end and the measuring column at an angle to the horizontal to reduce the vertical height

(a)  

A manometer with a vertical glass tube connected to a metal well, with the measuring liquid in the well at the same level as the zero point on the tube scale.

(a)  

Barometric pressure is a pressure reading made with a (a)  

Mechanical pressure sensor consisting of a thin, flexible disc that flexes in response to a change in pressure.

(a)  

A mechanical pressure sensor consisting of a hollow tube formed into a helical, spiral, or C shape.

(a)  

A mechanical pressure sensor consisting of a onepiece, collapsible, seamless metallic unit with deep folds formed from thin-wall tubing with an enclosed spring to provide stability, or with an assembled unit of welded sections.

(a)  

An (a)   is a device that converts input energy into output electrical energy

A (a)   is often used to convert the mechanical displacement of a diaphragm caused by a change in applied external force into an electrical signal

A diaphragm pressure sensor with a strain gauge as the electrical output element.

(a)  

A diaphragm pressure sensor with a capacitor as the electrical element.

(a)  

Diaphragm pressure sensor combined with a crystalline material that is sensitive to mechanical stress in the form of pressure.

(a)  

The term (a)   in pressure switches is the physical mechanical properties that dictate the difference between the pressure at which the switch activates (the setpoint) and the pressure at which the switch deactivates (the reset point).

A (a)   is an impulse line filled with noncondensing gas, used in level measurement applications

A (a)   is an impulse line filled with fluid that is compatible with the pressure-measuring device.

A (a)   is a surge tank that may be installed in a wet leg to prevent volume changes from forcing the fluid into the process as well as protecting the sensing element from high temperatures as with steam applications.

Pumps starting and stopping, valves opening and closing, and vibrations in the pipes can cause pressure pulsations. The response of pressure sensors is quite rapid and pressure pulsations can cause overranging in a gauge.

(a)  

(a)   can be added to inlet lines to limit pulsations and

surges.

High process temperatures can damage a pressure sensor. Adding enough inlet tubing to allow the process fluid to cool before entering the sensor may widen the useful temperature range of pressure sensors

(a)  

forms a water seal, or trap, between the sensor and the process, thus preventing high-temperature steam from entering the gauge.

(a)  

A (a)   is a hydraulic pressurecalibrating device that includes a manually operated screw press, a weight platform supported by a piston, a set of weights, and a fitting to connect the tester to a gauge.

Degree or intensity of heat measured on a definite scale. (a)   is an indirect measurement of the heat energy contained in molecules

is an instrument that is used to indicate temperature

(a)  

Lowest temperature possible, where there is no molecular movement and the energy is at a minimum

(a)  

Movement of thermal energy from one place to another. When objects are at the same temperature, they are in thermal equilibrium

(a)  

Heat transfer that occurs when molecules in a material are heated and the heat is passed from molecule to molecule through the materia

(a)  

Heat transfer by the movement of gas or liquid from one place to another caused by a pressure difference.

(a)  

Heat transfer by electromagnetic waves emitted by a higher-temperature object and absorbed by a lower-temperature object

(a)  

A thermal expansion thermometer consisting of a sealed, narrow-bore glass tube with a bulb at the bottom filled with a liquid. Liquid-in glass thermometers are commonly called glass-stem thermometers.

(a)  

An electrical thermometer consisting of two dissimilar metal wires joined at one end and a voltmeter to measure the voltage at the other end of the two wires.

(a)  

The (a)   is a thermoelectric effect where continuous current is generated in a circuit where the junctions of two dissimilar conductive materials are kept at different temperatures

measures the temperature of the isothermal block and calculates the equivalent reference voltage.

(a)  

An electrical thermometer consisting of a high-precision resistor with resistance that varies with temperature, a voltage or current source, and a measuring circuit.

(a)  

A temperature-sensitive resistor consisting of solid-state semiconductors made from sintered metal oxides and lead wires, hermetically sealed in glass.

(a)  

A simple process can often be described as a first order system. For a first order system, a time constant can be used to develop a model that describes the process.

(a)  

In most cases, temperature instruments cannot be used without protection from the environment in which they are used. A (a)   is a closed tube used to protect a temperature instrument from process conditions and to allow instrument maintenance to be performed without draining the process fluid.