Hot and Chilled Water
Measures circulation and distribution flow in commercial, institutional and district heating or cooling systems.
CMAG Magnetic Flow Meter for Hot and Chilled Water
The CMAG Magnetic Flow Meter employs a revolutionary tube design. The CMAG is most effective where flow profiling is unavailable. The CMAG opens up new and retrofit installations to huge savings in design, layout or reconstruction/modification.
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The Cadillac® CMAG magnetic flow meter is capable of measuring liquids of all types and consistency while providing an obstruction free flow path. Due to its unique flow tube/coil design, it is particularly suitable for new or retrofit into hot and chilled water systems where high accuracy is required and/or limited flow profiling or piping straight run is available. Employing a unique coil winding pattern and containment/focusing plates the Cadillac® magnetic flow meter does not require any flow profiling or piping straight run while still meeting the stated meter accuracy (+/-0.25% of rate). In any liquid measuring system the Cadillac® magnetic flow meter is the number one technology choice due to Cadillac’s® accuracy, linearity, reliability and rangeability.
Like many other flow meters, the Cadillac® magnetic flow 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 body with encapsulated coils, electrodes and an amplifier assembly. It detects velocity by measuring an induced voltage that is developed by moving the conductive fluid through a magnetic field.
The Hot/Chilled Energy Water Flow Meter of Choice
With its limited flow profiling or piping straight run requirement the CMAG makes an excellent choice for both Hot and Chilled water energy applications. The CMAG design will allow easy retrofit into tight mechanical rooms and basements, without affecting the measurement accuracy. In addition, the CMAG has the industry best turn-down at 300:1, which is ideal for the modulating flow rates common today with energy saving variable speed pumping systems.
The Water and Wastewater Industry Standard
With its limited flow profiling or piping straight run requirement the CMAG Magnetic Flow Meter makes an excellent choice for both water and wastewater applications. With line sizes common above 16 inches the CMAG allows new designs to eliminate long piping straight runs in order to get an accurate and reliable flow measurement. This significantly reduces the footprint of a building or other areas where the flow meters would be mounted. With increased wetted material selections most Water, including potable, applications have also looked to magnetic flow meters as the preferred choice, especially in applications requiring analog (rate) or pulse (totalized) outputs.
Technical Product Guide
CMAG Magnetic Flow Meter
Review the CMAG’s operating principle, applications, accuracy, flow ranges, installation requirements, dimensions, construction options and model configuration guidance for hot water, chilled water, hydronic and conductive-liquid flow measurement.
Confirm final sizing, wetted materials, outputs and disturbance-specific installation requirements with Cadillac Meter before ordering.
Product Overview
Full-Bore Magnetic Flow Measurement
The Cadillac CMAG is a rate-and-totalizing magnetic flow meter designed to measure electrically conductive liquids. It is particularly suited to hot water, chilled water, hydronic systems, pumped condensate and selected industrial process liquids.
The meter uses a full-bore flow tube with no moving parts and no obstruction in the flow path. This construction avoids the wear, pressure loss and regular mechanical servicing associated with many conventional flow-meter technologies.
Each meter receives a unique K-factor during a NIST-traceable flow test. The calibrated meter electronics use this value to calculate volumetric flow and provide instantaneous rate, accumulated total and configured outputs to local or remote systems.
Full-Bore Design
Provides an unobstructed flow path without moving measurement components.
Wide Rangeability
Supports variable hydronic and process loads with typical rangeability of 300:1 at the stated operating accuracy.
Flexible Electronics
Integral or remote electronics can provide indication, totalization and configured system outputs.
Traceable Calibration
Supplied with a meter-specific K-factor established through NIST-traceable flow testing.
Fluid requirement: The measured liquid must have an electrical conductivity of at least 3.0 µS/cm. CMAG is not intended for non-conductive fluids.
Applications
Where the CMAG Is Used
CMAG magnetic flow meters support liquid-flow measurement across HVAC, hydronic, energy-management and industrial systems. The measured liquid must be conductive and compatible with the selected liner, electrodes and grounding-ring materials.
Hydronic Energy Systems
Provides the liquid-flow input used with supply and return temperature measurements in HEATX and HEATX-2 energy systems.
Pumped Condensate
Supports hot-condensate measurement where the meter materials, temperature rating and full-pipe installation requirements are satisfied.
Metering and Cost Allocation
Supplies totalized flow information for customer billing, campus-wide systems and internal utility-cost distribution.
Building and Process Monitoring
Sends flow information to energy-management systems, distributed control systems and central monitoring locations.
Conductive Process Liquids
Can measure compatible conductive process liquids, including selected acids, caustics, abrasive fluids and liquids containing suspended solids.
Application review: Confirm fluid conductivity, chemical compatibility, temperature, pressure, flow range and installation orientation before selecting a CMAG configuration.
Operating Principle
How Magnetic Flow Measurement Works
The CMAG measures flow using Faraday’s law of electromagnetic induction. When an electrically conductive liquid moves through a magnetic field, it produces a voltage proportional to the liquid’s velocity.
The meter measures this induced voltage and combines the detected liquid velocity with the calibrated cross-sectional area of the flow tube. The converter then calculates volumetric flow rate and accumulated total.
STEP 01
Magnetic Field
Encapsulated and rigidly retained coils establish a controlled magnetic field across the full-bore flow tube.
STEP 02
Induced Voltage
Conductive liquid moving through the magnetic field generates a voltage proportional to its velocity.
STEP 03
Electrode Sensing
A pair of electrodes detects the induced signal without placing a moving measurement element in the flow path.
STEP 04
Flow Calculation
The calibrated K-factor and effective tube area convert the measured velocity into volumetric flow.
STEP 05
Display and Outputs
The converter displays rate and total and retransmits flow information through the configured outputs.
Meter-Specific Calibration
The relationship between liquid velocity and induced voltage is expressed through the meter’s K-factor. Each CMAG receives its own K-factor during a NIST-traceable flow test completed before shipment.
Conductivity Threshold
The measurement remains effective when the liquid’s electrical conductivity is at least 3.0 µS/cm. Fluid composition and wetted-material compatibility must still be reviewed during meter selection.
Features and Specifications
CMAG Performance and Construction
CMAG combines a full-bore stainless-steel meter body with electromagnetic measurement, meter-specific calibration and configurable electronics. Final specifications depend on meter size, body style, liner, electrodes, grounding rings, converter and selected options.
| Specification | Published CMAG Information |
|---|---|
| Measurement technology | Full-bore electromagnetic flow measurement based on Faraday’s law. |
| Accuracy | ±0.25% of reading under the stated installation and turndown conditions. |
| Typical rangeability | 300:1 at the stated operating accuracy. Published extended turndown bands provide reduced accuracy beyond 300:1. |
| Minimum conductivity | 3.0 µS/cm. |
| Meter body | 304 stainless-steel full-bore body with encapsulated and rigidly retained coils. |
| Grounding rings | Integral grounding rings are supplied with the meter. Material depends on the selected configuration. |
| Electronics | Integral or remote converter with indication and totalization options. |
| Published outputs | Analog 4–20 mA and pulse outputs. Communication and integration options depend on the selected system. |
| Displayed values | Instantaneous flow rate and accumulated total through the selected local or remote indication arrangement. |
| Calibration | Meter-specific K-factor established through a NIST-traceable flow test. A calibration certificate is provided. |
No Moving Parts
The meter does not rely on rotating or reciprocating mechanical measurement elements.
Obstruction-Free Path
The full-bore construction avoids a measurement obstruction within the liquid flow path.
Low-Flow Capability
Magnetic measurement does not have the mechanical low-flow cutoff associated with some alternative technologies.
System Integration
Rate and total information can be displayed locally or retransmitted to compatible monitoring and control systems.
Specification note: Accuracy, rangeability, temperature limits, pressure class, material compatibility and output availability must be confirmed against the complete ordered model and actual operating conditions.
Installation
CMAG Piping Requirements
CMAG uses magnetic-field and signal-processing techniques designed to reduce the straight-pipe requirements normally associated with conventional magnetic flow meters. The applicable layout depends on meter size and installation orientation.
Use the following 2024 size-specific diagram as the primary layout guidance. Confirm the final arrangement with Cadillac Meter whenever the installation includes unusual disturbances, restricted piping, gravity flow or critical billing accuracy.
| Installation | Published Layout Guidance |
|---|---|
| CMAG 3 inches and smaller | No upstream or downstream straight run is shown. Adjacent components may be installed flange-to-flange as illustrated. |
| CMAG 4 inches and larger | Maintain 1.5D from the flow-meter centreline upstream and 1.5D downstream. D is the nominal flow-meter diameter. |
| Vertical installation | Arrange the piping so the flow tube remains completely full and apply the size-specific straight-run requirement. |
| Gravity-flow installation | Use a wet-leg arrangement that keeps the piping and meter flow tube completely full during operation. |
The Flow Tube Must Remain Full
Magnetic measurement requires the electrodes to remain in contact with the conductive liquid. Do not install the CMAG where the meter can operate partially filled, drain empty or collect a persistent air pocket across the electrode plane.
CMAG Compared with Traditional Straight-Run Layouts
The comparison below illustrates the space that may be required by a traditional magnetic flow-meter layout using ten upstream and five downstream pipe diameters, compared with the CMAG’s published compact arrangement.
Engineering note: Valves, pumps, reducers, multiple disturbances and unusual velocity profiles can affect installation decisions. Confirm disturbance-specific requirements with Cadillac Meter before approving the piping design.
Sizing Guidance
Liquid Flow Ranges and Turndown
The published flow ranges below show the minimum and maximum configurable 4–20 mA spans for each listed CMAG meter size. They are selection boundaries rather than a recommendation to size the meter solely by nominal pipe diameter.
For accurate selection, provide the actual minimum, normal and maximum operating flows. This is especially important where billing accuracy or performance at extreme turndown is required.
| CMAG Meter Size | Minimum Volumetric Span | Maximum Volumetric Span |
|---|---|---|
| 0.5 inch | 0–0.250 GPM | 0–25.00 GPM |
| 1 inch | 0–0.750 GPM | 0–75.00 GPM |
| 1.5 inches | 0–1.750 GPM | 0–175.0 GPM |
| 2 inches | 0–3.000 GPM | 0–300.0 GPM |
| 3 inches | 0–8.000 GPM | 0–800.0 GPM |
| 4 inches | 0–12.50 GPM | 0–1,250 GPM |
| 6 inches | 0–25.00 GPM | 0–2,500 GPM |
| 8 inches | 0–50.00 GPM | 0–5,000 GPM |
| 10 inches | 0–75.00 GPM | 0–7,500 GPM |
Published Turndown Accuracy
The following accuracy bands are published with 1.5 pipe diameters measured from the flow-meter centreline upstream and downstream.
Up to 300:1
±0.25%
Published accuracy of rate.
300:1 to 400:1
±0.50%
Published accuracy of rate.
400:1 to 500:1
±1.00%
Published accuracy of rate.
Selection note: Do not assume the largest published span is appropriate for every application. Cadillac Meter should review the expected operating range, required accuracy and piping arrangement before the meter and output span are finalized.
Dimensions and Construction
Wafer and Flanged CMAG Bodies
CMAG is available in wafer and flanged body configurations. The published dimensions below are provided for preliminary planning. Confirm the final certified dimensions, flange standard, pressure class and ordered configuration before fabricating piping or supports.
All dimensions are in inches and all listed weights are in pounds.
Wafer Body — ANSI Class 150/300
| Meter Size | L1 | L2 | D1 | Weight |
|---|---|---|---|---|
| 0.5 inch | 2.76 | 9.33 | 1.93 | 17 lb |
| 1 inch | 3.15 | 8.90 | 2.60 | 21 lb |
| 1.5 inches | 3.94 | 9.80 | 3.35 | 25 lb |
| 2 inches | 4.33 | 10.43 | 4.02 | 29 lb |
| 3 inches | 4.33 | 11.46 | 5.00 | 35 lb |
| 4 inches | 4.72 | 12.72 | 6.26 | 40 lb |
Flanged Body — ANSI Class 150
| Meter Size | L1 | L2 | L3 | Bolts | Weight |
|---|---|---|---|---|---|
| 0.5 inch | 5.51 | 7.99 | 9.88 | 4 | 21 lb |
| 1 inch | 6.30 | 8.23 | 10.71 | 4 | 25 lb |
| 1.5 inches | 6.69 | 8.58 | 11.34 | 4 | 28 lb |
| 2 inches | 7.09 | 9.13 | 12.20 | 4 | 32 lb |
| 3 inches | 9.06 | 10.04 | 13.66 | 4 | 62 lb |
| 4 inches | 9.45 | 10.31 | 14.45 | 8 | 72 lb |
| 6 inches | 10.24 | 11.22 | 16.73 | 8 | 115 lb |
| 8 inches | 11.81 | 12.20 | 18.70 | 8 | 145 lb |
| 10 inches | 13.78 | 13.18 | 21.06 | 12 | 210 lb |
| 12 inches | 15.75 | 14.37 | 23.15 | 12 | 355 lb |
| 14 inches | 17.72 | 14.72 | 24.37 | 12 | 460 lb |
Available Construction Selections
Body Style
Wafer or flanged body, subject to size, liner and pressure-class availability.
Electrodes
Published selections include 316L stainless steel, Hastelloy C and other materials.
Liners
PTFE/PFA, polyurethane, EPDM rubber and ceramic options are shown in the model structure.
Grounding Rings
Published materials include 316 stainless steel, Hastelloy C and other specified materials.
Important: Material and liner availability varies by meter size and body style. Verify fluid compatibility, temperature rating, pressure class and certified dimensions with Cadillac Meter before purchasing or designing the installation.
Model Configuration
Understanding the CMAG Model Structure
A CMAG model number identifies the meter size, converter arrangement, body style, pressure class, electrode material, liner, grounding-ring material and selected options.
Use the published code structure below as a preliminary selection guide. Cadillac Meter should confirm the complete model number because not every combination is available in every size.
| Code Group | Code | Published Selection |
|---|---|---|
| Meter Size | A | 0.5 inch |
| B | 1 inch | |
| C | 1.5 inches | |
| D | 2 inches | |
| E | 3 inches | |
| F | 4 inches | |
| G | 6 inches | |
| H | 8 inches | |
| I | 10 inches | |
| J | 12 inches | |
| K | 14 inches; consult Cadillac Meter for larger sizes | |
| Converter | II | Integral converter with indicator and totalizer |
| RC | Remote converter | |
| Body Style | W | Wafer body; published with ceramic liner only and available through 4 inches |
| F | Flanged body | |
| Pressure Class | 150 | ANSI Class 150 |
| 300 | ANSI Class 300 | |
| Electrode Material | S | 316L stainless steel |
| H | Hastelloy C | |
| X | Other specified material | |
| Liner Material | C | PTFE/PFA; published temperature limit up to 250°F |
| U | Polyurethane | |
| D | EPDM rubber | |
| A | Ceramic; published temperature rating up to 350°F with remote converter | |
| Grounding-Ring Material | S | 316 stainless steel |
| H | Hastelloy C | |
| X | Other specified material | |
| Options | 24 | 24 VDC power supply; published input range 18–36 VDC |
| FM | FM approvals where available |
Remote Converter Structure
CMC
CMAG remote converter
R
Remote mounting
I
Indicator and totalizer
U
Universal mounting bracket
XXFT
Specified interconnecting-cable length in feet
Information Needed for Final Selection
Provide the liquid type, conductivity, chemical composition, minimum and maximum flow, temperature, pressure, nominal line size, flange class, piping orientation, required outputs, available power, display arrangement, communication requirements and approvals.
Energy-System Integration
Using CMAG in Thermal-Energy Systems
CMAG can provide the liquid-flow input for Cadillac HEATX and HEATX-2 energy systems. The energy computer combines measured flow with supply and return temperature data to calculate transferred thermal energy.
Available outputs and communications depend on the selected CMAG converter and energy-system configuration. Confirm the complete system architecture, power requirements and building-management interface during project selection.
CMAG with HEATX-2
CMAG and precision-matched temperature-transmitter assemblies provide the measured inputs used by the graphical HEATX-2 energy system. Building-management outputs depend on the selected panel configuration.
CMAG with HEATX
The CMAG flow signal and matched supply and return temperature assemblies feed the HEATX energy panel for hot- or chilled-water energy measurement.
Domestic Hot Water and Hydronic Heating
CMAG can measure water flow within steam-to-hot-water heat-exchanger arrangements serving point-of-use hot water or closed-loop hydronic heating systems.
Prepare These Details Before Requesting a Quote
- Liquid type, conductivity and chemical composition
- Minimum, normal and maximum flow
- Operating temperature and pressure
- Nominal line size and flange class
- Horizontal, vertical or gravity-flow piping arrangement
- Required accuracy, display, outputs and communications
- Available power and required approvals
CMAG Selection Support
Review the Complete Technical Guide
Download the consolidated CMAG guide for specifications, installation guidance, flow ranges, dimensions and model-selection information, or contact Cadillac Meter for application review and a project quotation.