Corner Tap - Fabricated Insert 1"-48"
The metering design shall be of the differential pressure producing type utilizing pure static
pressure sensed at the throat section.
The inlet section shall incorporate a hydraulic shape employing at least two vena contractae to
condition the flow profile before it enters the throat section. The laying length of the throat section
shall be at least 0.5 times the throat diameter. The outlet cone shall be truncated, having an
included angle of 10 degrees. The tube coefficient shall be constant for pipe Reynolds number
of 75,000 and greater and independent of line size.
The inlet and outlet cones and mounting flange shall be fabricated of carbon steel ASTM
Designation A515, Grade 55, 60, or 70.
The throat section shall be fabricated of stainless steel, ASTM Designation A182, A240 or A276,
Type 304. Inlet and throat pressure connections shall terminate at the outside of the holding
flange. The pressure connections shall be lined with stainless steel, Type 304 tubing. the Venturi
shall be designed for mounting between ANSI flanges as indicated in the piping schedule.
The metering element shall not have annular chambers, but shall have a single pressure
connection at the inlet and throat. The entire tube excepting the throat and pressure connections
shall be coated with an epoxy paint which meets the requirements of the United States EPA for
potable water applications.
The approval data shall state and substantiate the value and tolerance of the coefficient, the effect
of up and downstream piping configurations, the head loss in percent of differential pressure and
shall provide proof that the coefficient is independent of line size.
The accuracy shall be ± 1% of actual rate of flow over the flow range indicated in the tabulation.
This accuracy shall be substantiated by a two times standard deviation calculation of at least 30
calibrated tube coefficients of different line size and beta ratios.
The Venturi shall be a BIF Model 20183 or approved equal product.
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