Flow Metering that Outperforms in the Most Demanding Environments
Venturi Tubes • Precision flow measurement to meet varied requirements
Fluidic Techniques (FTI) offers Classical Style Venturi Tubes in a number of variations depending on the specific application and customer specification. The standard design is the Short Form Venturi, with specialized designs offered in Long Form, Pipeshell, Bi-Directional and Insert type.

Each FTI Venturi Tube is custom designed and manufactured to meet the customer’s specific flow measurement performance requirements for differential pressure, permanent pressure loss, piping requirements and accuracy of measurement.

FTI Venturi Tubes represent the highest standards in:
 
•  Accuracy   •  Energy Efficient  •  Application Versatility  •  Quality Control  •
 
ACCURACY  •   The FTI Venturi Tube’s accurate performance is well documented.
  The accuracy of the Classical Style Short Form Venturi Tube is well documented in the various published ASME and ISO Industry Standards and typically provides an uncalibrated accuracy of +/-1.5%. However, FTI’s extensive flow calibration data base indicates we can offer an uncalibrated accuracy of +/-0.75% based on the exacting fabrication techniques and precise machining tolerances incorporated in the manufacture of all FTI Venturi Tubes.
Throat forgings are lengthened to allow machining of the transition angles from the throat to the cones eliminating the potential of error due to grinding of the throat to cone welds.
When a higher degree of accuracy is desired, Venturi Tubes can be calibrated at a laboratory whose data are NIST certified to an accuracy of +/-0.25%.
ENERGY EFFICIENCY  •   The FTI Venturi Tube provides energy efficiency and reduced operating cost.
  Low permanent pressure loss (PPL) equates to energy efficiency and reduced operating cost. The Classical Short Form Venturi Tube has a lower permanent pressure loss than the orifice plate, annular orifice, flow nozzle, or wedge meter.
The Classical Short Form Venturi Tube has no sharp or bluff components susceptible to erosion like the square edge concentric orifice plate and incorporates a pressure recovery cone for enhanced pressure recovery.
Any modification of the ASME standard short form or long form designs may result in variations of this established PPL data and should be supported and verified by independent tests.
Truncated or shortened versions of both the Short Form and Long Form are available; however, the resultant PPL may be increased by as much as 25%.
APPLICATION VERSATILITY  •   Precision measurement in gas, liquid, steam, chemical, sludge and slurry.
  The FTI Classical Style Venturi Tube is suitable for precision flow measurement in gas, liquid, steam, chemical, sludge and slurry applications. Wide range (pipe Reynolds Number as low as 200,000), high pressure recovery, repeatability, sustained accuracy and short upstream piping requirements make it the preferred meter in many installations.
QUALITY CONTROL AND CERTIFICATIONS  •   Manufactured under the strictest controls and highest standards.

FTI maintains quality control at all points from receiving inspection of materials to final inspection of the finished product. Measurements of all critical dimensions are recorded and kept on file for five years.
FTI maintains a full range of qualified weld procedures to ASME Section IX standards using SMAW, SAW, GTAW, and FCAW processes. FTI holds ASME Power Piping (PP), CE/PED and CRN certifications. Complementing our special emphasis on welding techniques and equipment, the FTI inspection department is qualified to AWS-QC1 standards.
FTI offers a full range of Nondestructive Testing options. Inhouse capabilities include Gamma Radiography & Dye Penetrant Testing. On staff NDE Level II & Level III personnel are certified to ASNT recommended practice SNT-TC-1A. All other NDE disciplines are available to FTI through 3rd party sub-contracting.
Other special services include but are not limited to Postweld Heat Treatment, Hydrostatic Pressure Testing, Positive Material Identification and Ultrasonic Thickness Checking.
FTI Venturi Tube Construction
FTI Venturi Tubes are designed and manufactured in accordance with customer specified flow measurement standards. These standards include ASME Fluid Meters – Sixth Edition, ASME MFC-3M, ASME PTC 19.5, and ISO 5167.
FTI manufactures machined inlet and fabricated styles of venturi. The machined inlet has machined entrance, convergent and throat sections made from a single piece of material. Fabricated styles have pipe or rolled cylinders and formed cones or machined sections joined by welds.
Venturi Tubes generally consist of an Inlet Section, Convergent Section, Throat Section, Divergent Section and Outlet Section.
INLET SECTION
The Inlet Section consists of an inlet cylinder having an internal diameter equal to the customer’s upstream pipe. The inlet section may be flanged or beveled for welding. The inlet section is typically as long as the pipe internal diameter and contains the upstream or high pressure differential pressure tap.
CONVERGENT SECTION
The Convergent Section transitions from the pipe internal diameter to the throat diameter at an included angle of 21 degrees.
THROAT SECTION
The Throat Section contains the very important cylindrical section and the downstream or low pressure tap. In most cases, the throat (bore) diameter is calculated to produce the differential pressure at the flow rates and flowing conditions provided. The length of the cylindrical section of the throat depends on the flow measurement standard and the venturi style. The minimum length of the cylindrical section of the standard FTI venturi throat is one half of the throat diameter. For most fabricated venturis, the machined throat section is provided with additional length to transition from the throat to the convergent and divergent sections. The additional machined transition length is provided to eliminate deformation of the throat due to welding and the grinding of the cone to throat weld.
DIVERGENT SECTION
The Divergent Section transitions from the throat diameter to the pipe diameter at an included angle of 15 degrees for Short Form or 7 degrees for Long Form Venturis.


FTI Model V-100 / Flanged


FTI Model V-200 / Weld-in


FTI Model V-200 / Weld-in

OUTLET SECTION
The Outlet Section consists of an outlet cylinder having an internal diameter equal to the customer’s matching downstream pipe. The outlet section may be flanged or beveled for welding.
FLANGES
Flanged Venturi Tubes, Model V-100, are provided with raised face weld neck flanges as standard. Weld-In Venturi Tubes, Model V-200, are beveled in accordance with ASME B16.25.
DIFFERENTIAL PRESSURE TAPS
FTI Venturi Tubes are provided with one set of Differential Pressure Taps. Each set consists of one upstream (high pressure) tap located on the Inlet Section and one downstream (low pressure) tap located in the Throat Section. Differential Pressure Taps may be welded on the outside diameter or machined into the body according to the Venturi Style. Welded connections are in accordance with ASME B16.11.
Energy Efficiency  •  Cost Effective
The FTI Short Form Venturi is one of the most efficient differential pressure producing flow measurement devices available. It has lower permanent pressure losses (PPL) than an Orifice Plate, Annular Orifice, or Flow Nozzle as shown in the graph.
 
PRESSURE LOSS
(PPL) Permanent Pressure Loss
(% of Meter Differential)
Approximate Dimensions for FTI Short Form Venturi Tubes

Notes:
1. V-100 weights are calculated using 150# RFWN Flanged ends.
2. Above venturi weights and lengths are based on schedule standard pipe and 375” thick venturi wall.
3. Weights and lengths are approximate.
4. Above data is for ASME short form venturi only.
Ordering Information
1.
 FTI model number
2.
 Line size
3.
 Pipe schedule or actual I.D.
4.
 Differential pressure at maximum flow
5.
 Material of construction for body and throat
6.
 Flange, type and rating (if applicable)
7.
 Flowing medium
8.
 Maximum flow (specify units)
9.
 Operating pressure and temperature at maximum flow
10.
 S.G. @ base pressure and temperature
11.
 S.G. @ flowing conditions (liquid)
12.
 Compressibility factor @ operating pressure and base conditions (gas)
13.
 Molecular weight (gas)
14.
 Viscosity
15.
 System mechanical design conditions
®

Fluidic Techniques Division of FTI Industries, Inc..
1213 Antlers Drive, Mansfield, TX 76063 USA
Tel: (817)473-4481 • Fax: (817)473-6318