Flow Measurement Starts with Choosing the Right Sensor
Not all flow sensors are created equal — and the wrong choice can mean inaccurate data, missed leaks, or unnecessary installation costs. BluSENSE supports multiple flow measurement technologies, each with distinct advantages depending on your application, budget, installation constraints, and the range of flow you need to capture. Here's what you need to know before you buy.
Ultrasonic Flow Meters
The biggest advantage of ultrasonic flow meters is that they clamp directly onto the outside of the pipe — no cutting, no shutdowns, no disruption to the plumbing system. That makes them an attractive choice when opening up the plumbing is either impractical or undesirable.
The trade-off is cost — ultrasonic sensors are among the more expensive flow measurement options. They also have a low-flow limitation: most cannot reliably detect flow below 0.05 gallons per minute, which makes them a poor fit for leak detection, particularly small leaks.
Where ultrasonic sensors shine is in short to medium-term studies where you need to measure flow patterns or thermal energy consumption quickly and non-invasively. They're available for water, other liquids, and gases including natural gas. Output is typically 4-20mA, voltage signal, Modbus, or serial communication — all compatible with BluNODE CL and BluCORE.
Best for: Short to medium-term studies, thermal energy monitoring, applications where opening the plumbing is not practical
Not recommended for: Leak detection, low-flow applications
Pulse flow meters are in-line devices — the plumbing must be opened for installation. In many applications this is straightforward: water heaters, for example, are typically connected via flexible connectors that make installing a small pulse flow meter quick and easy. Pulse sensors can also be attached to read pulses directly from existing revenue meters installed by water utilities at the property line — no new hardware in the line at all.
Pulse flow meters offer considerable accuracy at a low price point, making them one of the most cost-effective long-term monitoring solutions available. Flow is calculated using a K-factor — a formula that correlates pulse count over time with flow rate, based on the pipe's inner diameter and the geometry of the turbine or flow wheel inside the sensor.
BluPULSE is purpose-built for pulse flow meters — with two dedicated pulse inputs, battery operation, and no wiring required at the meter.
Best for: Long-term deployments, budget-conscious projects, water heater monitoring, utility meter reading
Not recommended for: Applications where opening the plumbing is not an option
Pulse Flow Meters
Vortex flow meters are in-line devices — like pulse meters, the plumbing must be opened for installation. They are less expensive than ultrasonic sensors, making them a practical middle-ground option when clamp-on installation isn't required.
One important limitation: vortex flow meters cannot reliably read flows below 1 liter per minute (approximately ¼ gallon per minute), which makes them unsuitable for leak detection. Their key advantage over other in-line options is that they simultaneously measure pressure and temperature alongside flow — three measurements in one device, with no additional sensors required. Output is typically 4-20mA, voltage signal, Modbus, or serial communication.
Best for: Applications requiring flow, pressure, and temperature in a single sensor; cost-conscious projects where clamp-on installation isn't needed Not recommended for: Leak detection, very low-flow applications
Vortex Flow Meters
Magnetic flow meters work by measuring the voltage generated when a conductive liquid passes through a magnetic field. Because there are no moving parts inside the pipe, they are exceptionally well-suited for water or liquids that carry contaminants, suspended solids, or other particulates that would damage or clog mechanical sensors.
Like pulse and vortex meters, magnetic flow meters are in-line devices requiring the plumbing to be opened. Pricing sits in the mid-range and varies with accuracy requirements, but their unique characteristics make them the right choice — and often the only choice — when fluid quality is a factor. Output is typically 4-20mA, voltage signal, Modbus, or serial communication.
Best for: Contaminated or particle-laden fluids, applications where moving parts would be problematic, process water monitoring
Not recommended for: Non-conductive fluids, gases
Magnetic Flow Meters