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Accuracy
The uncertainty of flow nozzles is a function of design, pipe Reynolds
number, beta ratio (d/D), and piping configuration. Contact Wyatt
Engineering for further
information. If higher accuracy is desired, the flow nozzles
can be flow calibrated to produce flow measurement
uncertainties of ± 0.25%.
 Pressure
Loss
The permanent pressure loss of flow nozzles, expressed as a percentage
of the differential pressure produced, though not as high as orifice
meters, is significantly higher than the other differential producing
primary elements shown in Figure 1, above.
Beta Ratio
Wyatt Engineering furnishes flow nozzles with a wide range of diameter
ratios (d/D). By custom designing a meter for your application’s
flow conditions, Wyatt can provide an accurate and reliable primary
element.
Process & Environmental Conditions
Wyatt flow nozzles and meter runs can be fabricated for virtually
any set of process and ambient conditions. We design to ASME B31.1,
31.3, 31.8, or other
standards, as needed. A temperature range of -250 °C to +650
°C (-425 °F to +1200 °F) and pressures from vacuum service
to 35 MPa (5100 PSIG) can be accommodated.
Piping Requirements
Designed for full-pipe flow, Wyatt Engineering flow nozzles can
be mounted horizontally, vertically, or at an angle. Refer to the
appropriate standard or contact Wyatt Engineering for recommended
upstream and downstream piping and installation requirements.
Wyatt Engineering Flow Nozzles
- Flanged, Weld-In, and Pipe-Ring Types
- In Conformance with National and International Codes, as required
- Available in Stainless Steels, Nickel Alloys and Copper Alloys,
and Other Materials
- Available as Fully Assembled Metering Runs
(“Meter Tubes” and “Test Sections”)
Wyatt Engineering manufactures a full line of precision flow nozzles
for a wide variety of applications and installations. Most commonly
used for steam, condensate, and gas flow applications, all Wyatt
flow nozzles are made
to conform to the applicable ASME, ISO, DIN, ISA 1932, or ASHRAE
code. Nozzles are available for installation in 25 mm (1")
pipe and larger, and specially designed nozzle flow section assemblies
are available as well.
For most applications, flow nozzles should be made of stainless
steel or other corrosion- and scale-resistant material in order
to maintain their performance over extended periods. The typical
materials for nozzle construction are 304, 304L, 316, 316L stainless
steels and carbon steel. Nickel and copper alloys, titanium, duplex
stainless steels, PVC, and PTFE. Chrome-Molybdenum
alloyed steel flow nozzles are available for use in high temperature/high
pressure process conditions. Other materials are available for corrosives
and extreme applications.
Energy Considerations
As can be seen in Figure 1, the energy consumption of flow nozzles
is considerably higher than that for ASME venturi meters; more so
when compared to the BVT design. In fact, employing BVT venturi
meters will lower
permanent pressure loss and energy usage to about one-tenth of that
associated with the use of a flow nozzle. Alternately, Wyatt Engineering
can provide a diffuser cone on the outlet of the nozzle to lower
the losses associated with its use.
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