Magnetic Flow Meter Pressure Drop: What You Need to Know

Worried about pressure loss in your pipeline? Let’s clear up the confusion around magnetic flow meters.

Magnetic flow meters (mag meters) have no moving parts and create minimal pressure drop—typically less than 0.1 bar (1.5 psi) under normal flow conditions. Unlike restrictive devices (orifice plates, venturis), they maintain near-full pipe diameter, preserving system pressure efficiently.

Magnetic Flow Meter

Here’s why mag meters excel in low-pressure-drop applications

Do Mag Meters Have Pressure Drop?

Mag meters impact pressure far less than other flow technologies.

Their straight-through design avoids obstructions—electrodes are flush with the pipe wall. Pressure loss is 0.05–0.1 bar versus 0.5+ bar for orifice plates. This makes them ideal for low-head systems like irrigation or chemical dosing.

Key factors affecting pressure drop:

Pressure Drop Contributors in Mag Meters

Factor	Impact Level	Mitigation Tips
Pipe Diameter Match	Low	Avoid undersized meters
Liner Material	Minimal	Smooth PTFE liners reduce drag
Flow Velocity	Moderate	Stay within 1–3 m/s range
Installation Angle	None	Vertical/horizontal irrelevant
Electrode Protrusion	None	Properly flush electrodes

What Is the Pressure Drop in a Flow Meter?

Not all flow meters behave the same.

Magnetic flow meters typically show 0.01–0.1 bar loss (0.15–1.5 psi), while turbine meters lose 0.1–0.3 bar, and orifice plates can exceed 0.5 bar. Coriolis meters, despite moving parts, often match mag meters’ low drop due to their straight-tube designs.

Comparative analysis:

Pressure Drop by Flow Meter Type (at 10 m/s)

Meter Type	Typical Drop	Why?
Magnetic	0.07 bar	Unobstructed bore
Coriolis	0.08 bar	Straight tubes in some models
Ultrasonic	0 bar	No physical contact
Turbine	0.25 bar	Rotor creates drag
Orifice Plate	0.8 bar	Constriction forces high loss

Does a Flow Meter Reduce Pressure?

Only if poorly selected.

Well-designed mag meters reduce pressure less than an equivalent length of pipe. For example, a 6" mag meter adds pressure drop¹ equal to just 1–2 meters of straight pipe. Systems with tight pressure budgets should prioritize mag or ultrasonic meters.

Practical implications:

When Pressure Drop Matters Most

Application	Max Allowable Drop	Preferred Meter Type
Pump Discharge	0.2 bar	Magnetic/Ultrasonic
Gravity-Fed Systems	0.05 bar	Magnetic (oversized bore)
Slurry Transport	0.3 bar	Magnetic (liner-matched)
HVAC Chilled Water	0.15 bar	Magnetic/Coriolis

Pro Tip: For ultra-low-drop needs (e.g., seawater intake), specify full-bore mag meters with wafer-style connections and electrodes recessed 0.5mm to eliminate turbulence.

Conclusion

Magnetic flow meters introduce negligible pressure drop—often <0.1 bar—making them ideal for pressure-sensitive systems. They outperform most meter types while maintaining accuracy.