First Steps to Select the Right Flow Meter  
The initial step in choosing a flow sensor is determining whether flowrate data needs to be continuous or totalized, and if it requires local or remote access. For remote transmission, specify if it should be analog, digital, or shared—including the minimum data-update frequency for shared systems. After addressing these, evaluate the process fluid’s properties, flow characteristics, and the piping that will house the sensor. To streamline this, use structured forms requiring application-specific data (download the Flow Meter Evaluation Form).  

Fluid and Flow Characteristics  
List the fluid’s pressure, temperature, allowable pressure drop, density (or specific gravity), conductivity, viscosity (Newtonian or non-Newtonian), and vapor pressure at maximum operating temperature, noting how these properties may vary or interact. Include safety/toxicity details, fluid composition, presence of bubbles or solids (abrasive/soft, particle size, fibers), coating tendencies, and light transmission (opaque, translucent, transparent).  

Pressure & Temperature Ranges  
Specify minimum, maximum, and normal operating pressure and temperature. Also note if flow can reverse, if the pipe isn’t always full, if slug flow (air-solids-liquid) or aeration/pulsation may occur, if sudden temperature changes are possible, or if special cleaning/maintenance precautions are needed.  

Piping and Installation Area  
For piping, consider direction (avoid downward liquid flow), size, material, schedule, flange rating, accessibility, upstream/downstream turns, valves, regulators, and available straight-pipe runs. Assess the installation area for vibration, magnetic fields, power availability (electric/pneumatic), explosion hazard classification, and compliance needs (sanitary, CIP).  

Flow Rates and Accuracy  
Define the required meter range by identifying minimum and maximum volumetric/mass flows. Next, establish accuracy requirements, typically specified as % of actual reading (AR), % of calibrated span (CS), or % of full scale (FS). State accuracy separately for minimum, normal, and maximum flows—without this, performance may be unacceptable across the full range.  

In commercial applications (where meter readings determine transactions), absolute accuracy is critical; in others, repeatability may take priority. Specify both accuracy and repeatability for each application. Note that % CS or % FS accuracy increases absolute error at lower flows, while % AR maintains consistent absolute error across flow ranges. To compare bids fairly, convert all error claims to % AR, with separate % AR requirements for minimum, normal, and maximum flows. Bids should clearly state accuracy and repeatability at all three flow points.  

Accuracy vs. Repeatability  
When choosing between two meter types with similar performance, select the one without moving parts. Moving parts risk wear, coating issues, and “slippage” (unmeasured flow) due to clearance spaces, which varies with viscosity and temperature—temperature changes also alter meter dimensions, requiring compensation.  

Similarly, prefer full flow meters over point sensors when performance is equal. Point sensors only read accurately if inserted at the pipe’s average velocity depth, but this point shifts with flowrate, viscosity, temperature, and other factors, even after careful calibration.

Choose the right Flow meter type

Vortex Flowmeter VY Series

The Vortex Flowmeter VY Series is capable of measuring flow rates for liquids, gases, saturated steam, and superheated steam, while featuring self-diagnostic and remote maintenance capabilities. Its wetted components offer material options such as stainless steel (including duplex stainless steel) and nickel alloys. The series adheres to numerous standards, including explosion-proof and SIL2 certifications.  

External input support—via analog input for HART7 (with the analog input option) or through the MAO function block for FOUNDATION Fieldbus—enables enhanced calculation accuracy for parameters like mass flow rate and energy flow rate of liquids, gases, and steam. This improved performance is supported by built-in saturated and superheated steam tables. 

Proline Promag P 300 electromagnetic flowmeter  e&h

Field of Application  
Promag P is specifically designed for chemical and process applications involving corrosive liquids and high-temperature media. Its compact transmitter, Promag P 300, provides exceptional flexibility in operation and system integration, featuring one-sided access, a remote display, and enhanced connectivity options. Equipped with Heartbeat Technology, it ensures continuous compliance and process safety. 

SI0558  SID10XDBAKOA/US-100  IFM

• Reliable monitoring of liquids and gases in pipes
• Variable process connection using adapters
• Easy setting of the switch points for quick set-up
• Robust stainless steel housing for use in harsh industrial environments
• LED bar graph for indication of switch point and flow

VEGAPULS 6X

Radar sensor for continuous level measurement of liquids and bulk solids

VEGAPULS 6X is a universal sensor for continuous level measurement of liquids and bulk solids under all process conditions. Due to its application-oriented configuration and setup, VEGAPULS 6X offers a reliable and economical solution for all level applications. Due to its variable antenna systems, it ensures maintenance-free operation in all applications.

Your benefit

• Exact measuring results independent of process conditions
• Maintenance-free operation through non-contact measuring principle
• Application-oriented configuration enables a simple device selection

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