ISO TR 3313:2018 pdf download

ISO TR 3313:2018 pdf download.Measurement of fluid flow in closed conduits —  Guidelines on the effects of flow pulsations on flow-measurement instruments.
ISO TR 3313 defines pulsating flow, compares it with steady flow, indicates how it can be detected, and describes the effects it has on orifice plates, nozzles or Venturi tubes, turbine and vortex flowmeters when these devices are being used to measure fluid flow in a pipe. These particular flowmeter types feature in ISO TR 3313 because they are amongst those types most susceptible to pulsation effects. Methods for correcting the flowrneter output signal for errors produced by these effects are described for those flowmeter types for which this is possible. When correction is not possible, measures to avoid or reduce the problem are indicated. Such measures include the installation of pulsation damping devices and/or choice of a flowmeter type which is less susceptible to pulsation effects.
ISO TR 3313 applies to flow in which the pulsations are generated at a single source which is situated either upstream or downstream of the primary element of the flowmeter. Its applicability is restricted to conditions where the flow direction does not reverse in the measuring section but there is no restriction on the waveform of the flow pulsation. The recommendations within this document apply to both liquid and gas flows although with the latter the validity might be restricted to gas flows in which the density changes in the measuring section are small as indicated for the particular type of flow meter under discussion.
If the amplitude of the periodic flowrate variations is sufficiently small there should not be any error in the indicated flowrate greater than the normal measurement uncertainty. It is possible to define amplitude thresholds for both differential pressure (DP) type flowmetcrs and turbine flowmetcrs without reference to pulsation frequency. It is also possible to do this for vortex flowmeters but extreme caution is necessary if even the smallest amplitude is known to be present in the flow.
For DP-type flowmcters, the threshold is relevant when slow-response DP cells arc being used. In the case of turbine flowmeters, the threshold value is relevant when there is any doubt about the ability of the rotor to respond to the periodic velocity fluctuations. In the case of a vortex flowmeter the
At a given velocity pulsation amplitude a turbine flowmeter tends to read high as the frequency of pulsation increases and exceeds the frequency at which the turbine rotor can respond faithfully to the velocity fluctuations. The positive systematic error reaches a plateau value depending on the amplitude and thus the threshold amplitude can be defined such that the resulting maximum systematic error is still within the general measurement uncertainty. For example, if the overall measurement uncertainty is greater than or equal to 0,5 % then it can be assumed that a systematic error clue to pulsation of 0,1 % or less has negligible effect on the overall measurement uncertainty.ISO-TR-3313-2018

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