metrology

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Terms for subject Metrology (318 entries)

outlet run	Portion of the conduit upstream and downstream of the primary, whose axis is straight and in which the crosssectional area and shape are constant
output	Specification of the output signal which is the information signal delivered after the processing of the measured variable. For analogue and digital equipment, the size of output signal indicates unequivocally the size of the measured variable. For binary outputs, the output signal indicates the state of the measured variable
output signal	The type and characterising quantities of the output signal. The output signal might be electrical, mechanical, hydraulic, pneumatic, optical, digital etc. It may be variable over a specified range or assume specific values only. It the output is configurable, the possible operating modes should be described. If the output of a device, element or system is a foreign system interface, then the physical layer, transmission rate, transmission protocol and primary information parameters should also be specified
output span	The algebraic difference between the upper range-value and lower range-value of the output signal range
overload limit	The maximum input that can be applied to a device without causing damage or permanent change in performance
overrange limit	The maximum input that can be applied to a device without causing damage or permanent change in performance
overshoot	For a step response, the maximum transient deviation from the final steady-state value of the output variable, expressed in % of the difference between the final and the original steady-state values
pick-up	The primary element of a measuring chain which converts the input variable into a signal suitable for measurement
point drift	The change in output over a period of time for a constant input under specified reference operating conditions
polytetra-fluoro-ethylene	Usually as an extruded sleeve form not bonded to the meter tube, PTFE is generally suitable for use within the temperature range -50 °C to +200 °C. It has excellent wear resistance against small particles, and is chemically inert. It may collapse when subjected to subatmospheric pressures
polytetrafluoro-ethylene	Usually as an extruded sleeve form not bonded to the meter tube, PTFE is generally suitable for use within the temperature range -50 °C to +200 °C. It has excellent wear resistance against small particles, and is chemically inert. It may collapse when subjected to subatmospheric pressures
potentiostatic	Type of electrochemical measurement in which the working potential of the electrode is kept constant by external regulation
powder filling q	A type of protection of electrical apparatus in which the enclosure is filled with sand or other powder material of specified characteristics so that, in the intended conditions of service, any arc or high temperature occurring within the enclosure will not ignite the surrounding explosive gas atmosphere
pressure loss	A loss in pressure will occur as the fluid flows through the sensor. The magnitude of this loss will be a function of the size and geometry of the oscillating tubes, the mass flow rate (velocity) and dynamic viscosity of the process fluid
pressure piping	Small-bore piping connecting differential pressure transmitters to the pipe containing the orifice plate
primary device	Of an electromagnetic flowmeter: Device containing the following elements: - an electrically insulated meter tube through which the conductive fluid to be metered flows, - one or more pairs of meter electrodes, diametrically opposed, across which the signal generated in the fluid is measured, - an electromagnet for producing a magnetic field in the meter tube. The primary element produces a signal proportional to the flow rate and in some cases the reference signal
primary element	The primary element of a measuring chain which converts the input variable into a signal suitable for measurement
process conditions	Specification of the allowable process conditions under which the measurement equipment can be operated within its specified accuracy limits and/or without permanent impairment of its operating characteristics
process connection	Where appropriate, the type of process connections used by the measuring equipment, indicating nominal diameters, rated pressures and standards
Process Field Bus	Field bus developed by a consortium of mostly German firms and defined in German standard DIN 19 245, Parts 1-4

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