THE STEAM FLOW METER OF CHOICE

The Cadillac® CV Vortex flow meter has become acknowledged as the industry standard for direct steam flow measurement.

THE METER OF CHOICE FOR HIGH PRESSURE SATURATED AND SUPERHEATED STEAM

CV-HS The Cadillac® High Sensitivity (CV-HS) Vortex Meter is a rate and totalizing meter which is capable of measuring liquid, steam and gas. Due to it's rugged design it is particularly suitable for direct saturated steam measurement. In any steam system the Cadillac® Vortex Meter is the number one technology choice due to Cadillac®'s accuracy, linearity, reliability and rangeability.

Like many other flow meters, the Cadillac® Vortex Meter is a velocity measuring device which computes flow by multiplying the effective cross sectional area of the flow meter with the detected fluid velocity. The meter has no moving parts and consists of a meter & bluff body (shedder bar) and amplifier assembly. It detects velocity by measuring the frequency of the vortices, as they peel off the shedder bar of the flowmeter. The frequency of these “Karman” vortices is directly proportional to the velocity of the moving fluid, whether this is a gas or liquid.

APPLICATIONS

Data Source for energy management system, DCS, district-wide systems.
Energy-Customer Billing from accurately totalized flow measurements.
Basis for internal cost distribution using campus-wide systems.
Process monitoring from central control rooms.
Direct Steam measurements at both Boiler and point of use locations.
Natural Gas measurements for Boiler fuel flow.

FEATURES:

Accuracy

+/-1.0% of the reading for liguids, gas, and steam.
Rangeability

With seasonal steam load variation, the need for a large turndown is essential. Cadillac® Vortex Meters will accurately measure all load requirements with proper sizing. Typical turndown 15 to 1 or better.
Longevity

Mean time between failure (MTBF) of 50 years. With no moving parts and through simple robust design the MTBF of the shedder bar is 50 years. With proper system maintenance Cadillac® Vortex Meters will provide reliable,accurate service beyond all flow technologies.
Modern Electronics

Meeting the challenges of the information highway Cadillac® Vortex Meters are equipped with electronics capable of registering locally, remotely or interfacing with an energy management system. Built to withstand the toughest conditions.

PRINCIPLE OF OPERATION

The "Karman" vortex meter principle is clearly illustrated by a flag waving in the wind. As the air passes across the flag pole, vortices peel off and the flag is shaped by these pressure area’s. You will notice that, at low wind velocity, the flag will move slowly from side to side. As the wind increases, the flag will start to flutter and ripple, representing the increased frequency and intensity of these flag pole generated vortices as they pass. Wind velocity can thus be determined by measuring the frequency of that flutter.

The small vortex strut of the Cadillac Vortex Meter sheds the vortices, which then pass through an ultrasonic beam, generated by flush mounted transducers (see illustration), where they are detected and counted. The frequency of these vortices is directly proportional to the fluid velocity and exact volumetric flow rate is computed knowing the internal cross sectional area. Each vortex meter is tested to determine the relationship between velocity/flow rate and vortex frequency, which results in a meter K-factor expressed in "Pulses/Gallon". This volumetric relationship is then converted to relative engineering units, which the flow meter converter can then retransmit via a 4-20 mADC current signal or conditioned pulse.

An optional LCD Indicator/Totalizer can display and totalize in engineering units of the users choice. For compressible mediums, such as gases and steam, the meter amplifier can correct for temperature and pressure with the MASS option, which includes a temperature element in shedder bar and look up tables for ideal gases and steam. For mediums other than saturated steam an external pressure source must be provided as shown in the drawing below. Outputs from the meter with the MASS option are compensated and linear for the compressible medium being measured.

INSTALLATION

To ensure optimum performance and operation, Vortex meters should be sized to operate near or at the higher end of the operating range. This is due to the finite low end ability of the meter to generate and measure vortices. This is typically referred to as low flow cutoff. With other technologies on the market this low flow cutoff value is relatively high, thus requiring piping reductions as illustrated to bring the meter within a reasonable range for operation. In a typical steam heating system this is typically 1-2 pipe diameters.

However, with the Cadillac® Insertion/ Wafer Vortex technology, sensitivity is dramatically increased by placing the sensors integral for the flow body, which results in a significant reduction in low flow cutoff values. Resulting in full or existing line size meters and the cost savings of not having to manufacture and install reducing spool pieces.

GENERAL SPECIFICATIONS

Meter will consist of a Wafer style in-line or insertion type flow meter assembly with integral shedder bar.
Meter available with local or remote indication or blind housings.
Meter will provide analog (4-20 mADC) output.
Instantaneous and totalized flow available at local indicator. Instantaneous flow available remotely through output.
Meter measures flow using the Karman vortex shedding principle.
Vortices shall be detected by piezoelectric crystals.
Meter electronics shall be capable of direct MASS flow computation for saturated steam without external inputs.
Input power shall be 14-36 VDC, analog output shall be 4-20 mADC, 2-Wire.
Operating pressure/temperature of meter shall be (Vacuum to 900 psig)/(-40° to 650°F)

SIZING INFORMATION

The low-end performance of the meter is a function of the fluid's ability to generate a vortex, which using ultrasonic technology is at the very threshold of when vortices for a given fluid are shed. This threshold is dependent on fluid velocity, density and Reynolds number. The high end of the flow meter is amplitude limited, which ultimately impacts the electronics ability to distinguish one vortex from another. In most cases, this represents 250 ft/sec for gases and 25 ft/sec for liquids. To guarantee satisfactory performance, we will check every vortex meter application for suitability and will require process medium, pressure, temperature and expected minimum and maximum flow rates. For easy reference, we are providing you with a table (see below) for saturated steam at various pressures. The tables list the minimum and maximum flow capability, between which a flow measurement can be made at stated accuracy. Outside those limits, the accuracy will deteriorate somewhat, the extent of which will depend on the quality of the installation.