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The SMV 3000 with dynamic flow
compensation supports orifice
meters and the Meriam Laminar
Flow Elements. The SMV 3000
with density compensation supports
other flow elements such as
Venturi meters, nozzles, averaging
pitot tubes.
Averaging Pitot Tubes
Averaging pitot tubes are a low
differential pressure, insertion type
flow element and can be used in
clean steam, air, gas and liquid
applications. Since averaging pitot
tubes are insertion type elements,
they have lower installation costs
than many other primary flow
elements. The SMV 3000 can be
configured to compensate for
density and calculate flowrate for
liquids, gases and steam utilizing
averaging pitot tubes (Figure 4).
Figure 4 —SMV 3000 with
Averaging Pitot Tube
Support of Proprietary Flow Elements
Meriam Laminar Flow Element
Laminar Flow Elements (Figure 5)
are gas volume rate of flow
differential producers operating on
capillary flow principles and are
similar to averaging pitot tubes in
that they are low differential
pressure producers. They are
applicable over wider flow ranges
than conventional types of
primary flow elements and are
ideally suited for measurements
of combustion air and gases such
as argon, helium and nitrogen.
Laminar Flow Elements behave
according to the following flow
formulas and can be configured
for standard volumetric flowrate:
Q
= (B x h
+ C x h
v
w
(T
/T
) • (P
s
f
Where,
Q
= standard volumetric flowrate
v
B & C = calibration constants
h
= differential pressure
w
µ
= standard viscosity
s
T
= flowing temperature
f
P
= flowing pressure
f
ρ
= wet air density
w
ρ
= dry air density
d
And for mass flowrate:
• ρ
Q
= Q
m
v
Where,
Q
= standard volumetric flowrate
m
ρ = density at standard conditions
The relationship between
flowrate and differential pressure
can be determined two ways.
The first method uses a 6th
order polynomial equation that
custom fits the flow element.
The second method is an n-
segment fit (maximum n = 5)
between flow and differential
pressure which also custom fits
the flow element.
2
) • (µ
/µ
) •
w
s
w
/P
) • (ρ
/ρ
)
f
s
w
d
Figure 5 —SMV 3000 with Meriam
The SMV 3000 can use either one
of these methods as well as
compensate for density and
viscosity to increase the accuracy
of the flow measurement for the
Laminar Flow Element over
greater flow turndowns.
34-SM-03-01
Laminar Flow Elements
Page 5
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