LEFOO FS211 Thermal Electronic Flow Switch
LEFOO FS211 is a thermal electronic flow switch for water, oil or gas by variant. The distinction between a flow, pressure, temperature, protective or remote-actuator contact matters when selecting replacements.
Model Identification & Key Specifications
Original Manufacturer Data
Thermal calorimetric principle with heated and reference resistors detects LIQUID/GAS velocity, without moving piston. OEM selectable 1–150cm/s water, 3–300cm/s oil and 20–2000cm/s gas; 8sec startup and typical 2sec response make it inappropriate for instantaneous no-flow protection. PNP/NPN transistor up to 400mA versus relay type up to 4A are different output choices; original current manufacturer webpage confusingly writes 230V ±15% DC alternative, requiring exact configured supply/manual verification rather than applying 230VAC blindly. Stainless probe, PBT housing, IP67, 100bar proof. Non-Ex unless independently certified.
Confirm the manufacturer original model/order suffix, correct operating medium and mounting, switched load and power supply, safety device architecture, verified original maker photograph and applicable current approval documentation. Use the latest model-specific manufacturer technical references and correct photographs.
AirAlign Engineering & Variant Comparison
A heated/reference-resistor calorimetric sensor is not a mechanical piston flow device. The OEM startup can take up to 8 seconds and normal response around 2 seconds. An unusual manufacturer power-supply notation for a 230 V option requires original order-code/manual confirmation before electrical design.
Always identify whether the part measures a continuously variable signal, provides a discrete protective trip or controls an operating cycle. Component substitution should preserve sensing topology, switching hysteresis, reset and energized/deenergized states. Enclosure and cable routing must be assessed within the actual equipment, not only against a standalone catalogue illustration.
Installation and Integration Checks
Check supply voltage, relay versus transistor wiring, contact NO/NC state and peak inductive duty. Signal outputs are not equivalent to motor-control contacts.
Distinguish temperature difference from independent thermal limits, and paddle/piston/calorimetric flow measurement from pressure differential. Match actual calibration media.
Mount as specified for the device’s reference sensor or mechanical paddle; verify working medium, housing, ingress protection, maximum process temperature and cable/port fittings.
Confirm applicable safety function and approvals for the exact order-code revision. Match any applicable CE, UL or TÜV documentation to the exact device configuration.
Related Products
LEFOO FS213 · LEFOO FS200 · LEFOO manufacturer profile
Official Manufacturer Sources
Independent AirAlign engineering page. Device-specific maker photo and current exact-variant third-party approvals require separate verification.
FS211 — thermal liquid or gas flow switching
FS211 is an electronic thermal flow switch with medium-dependent velocity bands; the maker’s water, oil and gas ranges must not be mixed as one universal calibration. Heat-transfer sensing depends on temperature, fluid type, and probe insertion, so verify the order’s medium-specific setup and switching hysteresis. Commission the discrete output and fault state before using it for pump flow proving. A thermal switch is not an intrinsically calibrated process flowmeter.