Forbes Marshall

Forbes Marshall Vortex Flow meter VFM 7000

Forbes Marshall steam flow meter model VFM5090SSM has built in temperature sensor and an optional pressure sensor. The steam tables are programmed in the electronics to provide a very accurate reading even when pressure and/or temperature changes. VFM5090SSM is a dedicated steam meter which has extremely powerful diagnostics - it can even diagnose installation errors like the ones caused due to gasket protrusion or a meter not being centered.

Features:

No mechanically moved parts
High measuring accuracy
Sandwich type DN25 to 150 (1" to6")
Compact unit, maintenance-free
Microprocessor based digital signal converter using SMD technology
Powerful LCD display with excellent readability
Integrated volume / mass totalisers
Full programmable parameters like flow range, Eng. units, medium constants, current / frequency outputs
Flameproof
CSA No. 204493
Class 1 Zone II C
Class 1 division 2 Group a,b,c,d
F M approval-pending
Built-in self diagnostics
Wetted parts of SS 316L/304 and titanium
Meter sizes DN 10S to 200 (3/8" to 8")
Small sizes DN 10S to 20 (3/8" to 3/4") with integral U/S & D/S pipes & flanges
High range ability / turn-down ratio
Simple programming with magnetic sensors and bar magnet without having to open the cover of the electronic housing
On-line temperature / pressure compensation & mass flow computation with built-in temperature and pressure sensors
Special applications specific software

Measuring Principle

The Vortex Flow meter 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 the 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 "Kaman Vortex Street" with alternating pressure conditions whose frequency f is proportional to the flow velocity v. The non-dimensional Strouhal number S (primary head constant) describes the relationship between vortex shedding frequency f (in Hz), width b of the body and mean flow velocity v (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 analyzed in the signal converter.

VFM 7000 SSM
Saturated Steam Meter with built-in Pt 1000 temperature sensor and measuring mass flow rate of steam with online density compensation.

VFM 7000 CFM
Condensate Flow Meter with built-in Pt 1000 temperature sensor and measuring mass flow rate of steam condensate with online density compensation.

VFM 7000 GFM
Gas Flow Meter with built-in Pt 1000 temperature and pressure sensors and measuring the normalized volumetric or mass flow rate of gas with online pressure, temperature and compressibility factor (PTZ) correction. compressibility factor correction using the Redlich - Kwong Equations.

VFM 7000 FAD
Free Air Delivery flow meter for compressed air with bulit-in Pt 1000 temperature and pressure sensors, measuring the normalized volumetric or mass flow rate of compressed air with online pressure, temperature and compressibility factor (PTZ) correction and facility to programmed the compressor motor RPM and Relative Humidity (RH) for computing the FAD.

VFM 7000 NGM
Natural Gas Meter with built-in Pt 1000 temperature and pressure sensors with added facility to programmed the gas composition and density computation according to American Gas Association standards, AGA 8. Detailed Characterization Method is used in the computation of compressibility factor and density correction.

VFM 7000 HM
Heat Meter with built-in Pt 1000 temperature sensor to directly measures the heat content of steam, hot water or chilled water with density correction. It has two separate internal totalisers - one for the mass flow and the other for the heat content.. A Look-up table for the specific Enthalpy vs. Temperature is programmed in the unit for heat / energy calculation.

VFM 7000 NHM
Net Heat Meter. An extension of VFM 7000 HM with a provision for the second temperature input, 4 - 20 mA, from an external temperature transmitter. It measures directly the net heat imparted to the process in the case of heating using steam, hot water, and heat extracted from the process in the case of cooling using chilled water. It also supports direct display of the billed amount in different currencies.