Description
3.4 Theory of Operation
FUS1010 IP65 NEMA 4X & IP66 NEMA 7
26 Operating Instructions, 01/2013, A5E02951520-AC
① Fluid velocity near the axis of the flow stream tends to be greater.
The Reynolds number is then computed as follows:
5Q 3LSH,'9
)
9LVFRVLW\
where:
viscosity = cS = cP/density
Pipe ID = inches
V
F
= inches/sec
cS = kinematic viscosity
cP = absolute viscosity
The flow meter then uses this computation of Reynolds number to compensate the raw flow
velocity for conditions of laminar or turbulent flow profile as defined by an internal Reynolds
compensation table. The flow meter then converts the compensated flow velocity to
volumetric flow rate.
Rate = V
F
* Comp(Rn) * Pipe area
Volume Correction Algorithm
The flow meter provides Standard Volume output by inferentially determining the liquid API
@ 15.6°C (60°F), or the specified base temperature, and then applying the API standard
(2540) algorithm as outlined below. Before describing API algorithm the steps required to
obtain bulk or actual flow should be reviewed.
Based on the measured transit time difference (Δt), average transit time (T
N
) and pipe
dimensions, the RAW flow rate (FLOW
RAW
) and liquid sonic velocity (VoS) are computed.
Using the liquid temperature input (Standard on FUS1010) and the optional user provided
pressure input, the measured VoS is then compensated to the value expected for base
temperature and pressure conditions (i.e. 15.6°C and 1 BARA or 60°F and 14.7 PSIA). This
compensated VoS is called LiquIdent.
LiquIdent = VoS + TempSlope * (t - base temp) + PresSlope * (p - base pressure)
where: t = measured temperature (°C or °F)
TempSlope = change in liquid sonic velocity per °C or °F (Linear for petroleum products.)
PresSlope = change in liquid sonic velocity per PSI (Linear for petroleum products.)
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