Flow - Series M21 | Tecfluid

Variable Area Flowmeter Tecfluid M21

The Tecfluid M21 is a metal variable area flowmeter designed for low flow measurement of liquids, gases, and steam. The float moves within a calibrated tapered tube, and its position is transmitted to the indicator via magnetic coupling, eliminating fluid ingress into the indicator housing.

Operating Ranges and Conditions

• Water: 0.4–1000 l/h
• Air: 12 Nl/h–30 Nm³/h
• Accuracy: ±4% of reading, per VDI/VDE 3513 sheet 2
• Turndown ratio: 10:1
• Fluid temperature: -80…+250 °C (no switches), -20…+200 °C (with switches or transmitter)
• Pressure rating: PN16 with regulating valve, PN40 without valve

Connections and Materials

Body and float: EN 1.4404 / AISI 316L. Connections: ¼”–¾” BSP or NPT, with sanitary options (ISO 2852, SMS 1145, DIN 11851, TRI-CLAMP®). Indicator housing: standard aluminum IP65, optional stainless steel AISI 316L IP67.

Variants and Options

• M21-R / N: vertical BSP/NPT connection
• M21-HR / HN: horizontal connection, no valve
• M21-HRA / HNA: horizontal connection with valve
• M21-1 / 3 / 7 / 30: sanitary connections
• M1-AMD: 1 or 2 NAMUR inductive switches (EN 60947-5-6)
• TH6 / TH6H: 4–20 mA transmitter, HART protocol (TH6H)
• MT03A: converter with optional MODBUS RTU RS485

Installation Guidelines

Install vertically with upward flow. Deviation of 5° from vertical may cause 8–10% reading error. Use upstream filter (max opening 200 μm). Recommended straight pipe: 5 × DN upstream, 3 × DN downstream.

Typical Applications

Control panels, pilot plants, laboratories, gas burners, small chemical lines, pharmaceutical and cosmetic processes, heating/cooling circuits. For gases and steam, a float damping mechanism is available for stable indication.