Corner Tap - Insert 4"-24"
The metering design shall be a differential pressure producing type designed for insertion within the pipeline
and utilizing pure static pressure sensed at the throat section. The differential pressure shall indicate static
pressure change only.
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 throat section shall be a cylindrical section having a
laying length at least 0.5 times the throat diameter. The low pressure tap shall be included in the throat
section. The pressure recovery section (outlet cone) shall be truncated and have an included angle of 10
degrees. The metering element shall not utilize annular chambers, and shall have a single pressure
connection at the inlet and throat. Each pressure connection shall be designed to allow rodding of the
pressure passage from the flow element exterior.
The entire tube, inlet cone, outlet cone, throat section and integral holding flange shall be fabricated of epoxy
vinyl ester resin, DERAKANE* reinforced with not less than 30 percent fiberglass by weight. The entire
venturi-cones, throat section, and holding flange - shall be an integrally molded one piece unit. All interior
surfaces of the FRP insert shall have a hardened gel-coat. Inlet and throat pressure connections shall
terminate on the holding flange and extend beyond the outside diameter of the mounting flanges. Pressure
connections shall be Type 316 stainless steel, ASTM Designation A276.
The Venturi shall be designed for mounting between ANSI B16.1 flanges as indicated in the piping schedule.
The manufacturer shall furnish data substantiating meter proportions and performance which should include:
Meter coefficient value and tolerance, proof that the coefficient is constant above a Reynolds Number of
75,000 and independent of beta ratio and line size, the value of the permanent head loss as a percent of the
differential pressure produced, a flow versus differential curve for the specific application described, and data
showing the effects of typical installations of fittings immediately upstream of the meter; including increaser,
decreaser, and elbow. All submitted data shall be certified by the manufacturer.
The un-calibrated accuracy of the flow meter installed per the manufacturers recommendation shall be ±
0.75% of actual flow rate over a range of at least 10 to 1. This accuracy shall be substantiated by a two
times standard deviation calculation of at least 30 calibrated flow meters of different line sizes and beta
ratios. The manufacturer shall warrant its primary flow meter for a period of not less than 25 years against
defects in materials and workmanship.
The meter shall be a Model 20182 as manufactured by BIF and shall satisfy all project requirements, or an
approved equal.
* DERAKANE is a registered trademark of the Dow Chemical Company
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