SCFP - WEDGE TYPE FLOW
METER
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PLEASE NOTE:
Primary Flow Signal, Inc., possessing superior engineering,
flow measurement and design capabilities, offers its "Standard Code Flow
Products" (SCFP) as a convenience to its customers. However, PFS, Inc. makes no claim
or warranty, implied or expressed as to the performance or applicability of any SCFP
except that such products shall be fully conforming to any and all Codes according to
which such SCFP products are manufactured, and shall be of the highest quality. Unless
otherwise specified at time of order placement, PFS, Inc. shall provide SCFP according to
ISA standards.
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PRIMARY FLOW SIGNAL provides the
PFS-WM Wedge Type Flow Meter
NOW, MORE THAN EVER, PFS CAN TRULY BE YOUR ONE STOP PRIMARY
FLOW MEASUREMENT RESOURCE!
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In line sizes from
0.5" through 24", the Wedge Type Flow Meter is a differential producer design in
the Public Domain which, when utilized, is generally applied in air entrained liquid,
particulate entrained, high viscosity or slurry type, most frequently described as
difficult-to-meter line fluids. Abrasive or fibrous slurry are examples of possible
applications.
Relatively low pipe Reynolds Numbers can be addressed with some accuracy and the discharge
coefficient is stable through the application range.
Though accuracy, reliability and headloss characteristics are inferior
to that obtained with PFS's HVT (Halmi Venturi Meter) product line(s), if highly viscous,
particulate laden flows along with low acquisition cost is of highest priority to the
exclusion of the other factors, the PFS-WM Wedge Type Flow Meter can be a metering option
worth consideration.
When your application requirements dictate the use of Wedge Type Flow
Meters, PFS, Inc. can provide expert technical assistance calculating bore size,
differentials and flow rates coupled with high quality and economically priced units to
best fit your needs.
Naturally, if you have particular requirements which do not appear in our standard
offering, please do not hesitate to ask, since we will gladly design and manufacture to
your specific needs. |
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DESIGN AND
OPERATION INFORMATION
The basic system consists of a cylindrical pressure vessel into which a constriction
"wedge" is fabricated thereby leaving a open segment of a known height.
Pressure taps which receive the (extended) sealed sensors on either side of the
"wedge" provide the differential signal to the PFS Flow Transmitter which is
then related, by formula, to the rate of flow occurring through the open segment.
Since no relationship of geometric similitude exists between designs of varying line
sizes, No Manufacturer can reliably state a general accuracy, and 2 Sigma confidence is
not applicable. |
All PFS-WM Wedge Type
Flow Meters are Laboratory (Wet) Calibrated for the Application
Conditions Providing a +/- 0.50% of Coefficient Accuracy for the Calibrated Range. |
MATERIALS OF
CONSTRUCTION
The PFS-WM Design can be produced using a wide
variety of materials depending upon the particular service requirements of the specific
application. Typical materials selections, however, include Carbon steel, 304 and 316
Stainless steel, Monel, Hastelloy, and PVC for Chlorine and similar chemical applications.
The Sealed Sensor assemblies are of 316 Stainless steel with armored
capillary conduits containing . |
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RELY
ON PFS ENGINEERING EXPERTISE TO PROVIDE YOU WITH TECHNICAL
ASSISTANCE IN ALL OF YOUR FLOW MEASUREMENT REQUIREMENTS. |
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| FLOW CALCULATION THEORY: |
The line fluid is forced
downward similar to a segmental orifice plate, but is guided along a sloping
"wedge" shape rather than a sharp edge. The pressure taps are located upstream
and downstream of the wedge and in all cases are equipped with Sealed Sensors.
The differential produced by the device is a
function of the ratio between the wedge segment opening, H, and the diameter of the body,
D. |
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| The equivalent beta ratio therefore is: |
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| Discharge coefficients are as follows for line sizes
indicated: |
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| Line Size 0.5":
Line Sizes 1.5" through 24":
Line Sizes 1"
through 1.5": |
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and the mass flow rate equation for
incompressible flow is:
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The calculations for compressible flow are
similar but must account for temperature and Adiabatic Expansion and Compressibility
factors.
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Please
Note:
1.) The foregoing calculations not withstanding, all Wedge Type Meters must be
properly calibrated in order to provide an accuracy statement.
2.) The accuracy of the PFS-WM is +/- 0.50% of Coefficient for the Calibrated Range. |
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Please
Contact your PFS, Inc.
Sales Representative.
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