Change of measure or range: spectrum or set of variable values as they fall within the upper or lower limits of measurement capability or transmission of the instrument, is expressed by setting the 2 extreme values. (0-100 bar). Rangeability: the quotient of the value of top and bottom as an instrument also called dynamic or far, dimensionless. Scope or span: The difference between the upper and lower measurement range of the instrument. Error : algebraic difference between the measured or transmitted by the instrument and the actual value of the measured variable. Uncertainty: the spread of values that can reasonably be attributed to the true value of the measured quantity, (each time is measured with a instrument, is known not to be exact).Accuracy: is the quality of a measuring instrument which tends to give readings close to the true value of the measured quantity. Accuracy: tolerance is the measurement or transmission of the instrument and defines the limits of errors made when the instrument is used in normal service conditions, is expressed as:% of range, variable units of measure,% of reading completed,% of full scale or measurement range. Dead Zone: is the field of values of the variable that does not change the indication, ie produces no response is expressed as both% range. Sensitivity: is the reason for the increase of reading and increasing the variable that results achieved after the resting state indicated as% of range, it produces response.Repeatability: the ability to reproduce the position of the pen or index or instrument output signal. By repeatedly measuring the same variable values under the same conditions of service and in the same sense of variation, covering the entire field. Reproducibility describes the closeness of the output readings for the same entry when no change in the method of measurement ( the observer, measuring instrument, measurement, conditions of use and time of measurement), usually expressed in% of span over a period of time. Hysteresis: the maximum difference observed at the levels indicated by the pen index or instrument to the same value as any of the field when the variable goes full scale in both directions either upward or downward, is expressed as% of spanMeasurement range zero elevation: It is one in which the zero value of the variable or measured signal is greater than the lowest value of the field. Field with suppressed zero measure: it is one in which the variable or zero measured signal is lower than the lowest value of the field. Elevation zero is the amount by which the zero value of the variable exceeds the lower value of the field. Can be expressed in units of the measured variable or percentage range. Suppression of zero-sum to the value lower than zero field of the variable. Unit can be expressed as a percentage or variable range. Drifting: is the change in output that occurs in a period of time while holding constant the measured variable and all environmental conditions. It is widely believed that zero drift is the change of variable to zero of it due to any internal cause, and the thermal drift of zero where the variation is due only to temperature effects. Usually expressed as a percentage of the output signal of full scale at room temperature or temperature change intervals.Resolution: magnitude of step changes in the output signal to be changing continuously as the entire field. Reliability: A measure of the likelihood that an instrument continued to behave within the error limits specified over a given time and under specific conditions. Stability: ability of the instrument to maintain his behavior during its life and specified storage. temperature: temperature field which is expected to work the instrument within specified error limits. Noise: any accidental electrical disturbance or unwanted signal that changes the transmission, display, or record the instrument. Linearity: This is the approach that has a calibration curve to a straight line specified.Service life: minimum specified time during which applies the characteristics of continuous and intermittent instrument without submitting changes beyond the specified tolerances. - Instruments blind are those who have no visible indication of the variable eg pressure switch instruments and alarms and thermostats. They are also blind instruments flow transmitters, pressure, level and temperature without indication. Instruments indicators: you have an index and a scale where they can read the value of the variable. According to scale the amplitude of the indicators are divided into concentric and eccentric. Are also considered with digital tools. Recording instruments: are those recorded with continuous strokes or dots of variable and may be circular, rectangular or elongated graphic as the shape of the graph.Primary elements are those instruments that are in contact with the variable and use, or absorb energy from the controlled environment for the measurement system in response to an indication of the variation of the variable. The effect of primary-elect may be a change of pressure, force, position or power measurement, not necessarily related to the variable nature of the prosecution if their variation. Transmitters: capture the process variable across the element primary and remote transmit through pneumatically (3 to 15 psi) or electronic (4 to 20 mA DC). Other electronic signals are used (1 to 5 mA DC, 10 to 50 mA DC, 0 to 20mA DC, 1 to 5 volt and 10 to -10 volts). The parent may be part or not the transmitter. The transducers: receiving an input signal based on one or more physical quantities and not modified or converted to a signal. Transducers are a relay, a primary element, transmitter, converter, etc..Converters: These are instruments that receive an input signal from pneumatic or electronic instrument sent after a modification resulting in a normalized output signal ie P / I converter is a pneumatic input signal (p) and electronic output (I). Element recipients: they receive the signal from the transmitters and to indicate or record. The drivers: comparing the controlled variable (pressure, level, temperature) to a desired value, and conduct corrective action in accordance with the deviation. The controlled variable can be received directly in the case of the local controllers or indirectly via pneumatic signal, electronically or from a digital transmitter. Final control element: the controller receives the signal and modifies the flow of the fluid or agent control. In a pneumatic control valve is typically a pneumatic tire or a servomotor to an electronic control or servo valve is actuated through a converter of pressure intensity in the electronic control is also often used a motorized valve.