Keterangan :

Forbes Marshall Vortex Flowmeter VFM 8700 for gases, steam and liquids

Measuring Principle

The Vortex flowmeter is used for measuring the flow velocity of fluids in pipelines. The measuring principle is based on the development of a Karman Vortex shedding street in the wake of body built into the pipeline.

The periodic shedding occurs first from one side and then from the other side of a bluff body ( Vortex shedding body) installed perpendicular to the axis.

Vortex shedding generates a so-called " Karman Vortex Street" with alternating pressure conditions whose frequency is proportional to the flow velocity The non dimensional Strouhal number ( primary head constant) describes as relationship between the vortex shedding frequency ( in Hz) , width b of the body and the mean flow velocity ( in m/ s) .

f = S. v / b

The flexural vibration of the vortex-shedding body is picked up in the primary head via sensors and analysed in the signal converter.

Features

! No mechanical moving parts
! High measuring accuracy
! Compact unit, maintenance-free
! Dotmatrix LCD display with excellent readability
! Integrated volume/ mass totalizers
! Full programmable parameters like flow range, engg. units, medium constants, current/ pulse outputs, meter parameters etc.
! Microprocessor based digital signal converter using SMD
technology
! Built-in self diagnostics
! Wetted parts of SS 316L/ 304 and Titanium
! Meter sizes flanged DN 10 to 200 ( 3/ 8" to 8" )
! Sandwich type DN 10 to 150 ( 3/ 8" to 6" ) inclusive of upstream & downstream sections for sizes less than DN 25 ( 1" )
! High range ability / turn-down ratio
! Simple programming and user-friendly interface
! Current, pulse outputs, HART as standard.
! External programming with magnetic sensors and bar magnet without having to open the cover of the electronic housing
! Online temperature/ pressure compensation and mass flow computation with built-in temperature and optional pressure sensors. Integral pressure sensor is not feasible for remote mounted signal convertor for pressure or temperature
! Optional 4-20 mA input
! Built-in electronics and sensor diagnostics

Special application software:
! Saturated Steam Flow Measurement
! Compressor FAD Metering
! Heat Metering
! Condensate Metering
! Gas Flow Metering
! Net Heat Metering
! Tonnage of Refrigeration

Application

! For flow velocities up to 7 m/ s ( 23 ft) for liquids and 75 m/ s
( 246 ft) for gases.

! Specially developed for Steam Flow Measurement applications.

! Measurement of low conductive liquids.

! Manual Density Correction can give flowrates in kg/ hr ( lb/ hr)
for steam and Nm / hr ( scfm) of gases