LEFOO FS51 and FS52 Vane Liquid Flow Switches
LEFOO FS51 / FS52 is a vane liquid flow switches for water / approved compatible liquids. The distinction between a flow, pressure, temperature, protective or remote-actuator contact matters when selecting replacements.
Model Identification & Key Specifications
Original Manufacturer Data
Mechanical stainless PADDLE water flow proving, not FS200 piston and not FS211 thermal sensing. OEM FS5 series offers 3 paddle lengths for nominal pipe 25–75mm, optional 6in fourth paddle for 100–150mm. Actuation m³/h varies hugely with pipe diameter and number of paddles; a single universal flow setpoint is invalid. Maker advises horizontal pipe orientation, or VERTICAL UPFLOW only, never vertical downward flow or reverse-flow operation. OEM original FS52 housing offers larger wiring space; 250VAC 10A, max operating approx 10.34bar, water up to 120°C and IP53. These are not licensed exact variant photos yet.
Check the exact installed model/option, cable and contact topology, medium compatibility, current certificate and the system-specific installation regulations. Confirm the product’s exact model, supplier imagery, current approvals and the configured order code.
AirAlign Engineering & Variant Comparison
Paddle and pipe dimension determine trip flow. The manufacturer describes correct horizontal or vertical UPFLOW mounting; vertical downward or reverse flow is unsuitable. FS52’s larger wiring compartment is a housing distinction, not evidence of an identical trip threshold.
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 FS200 · LEFOO FS211 · LEFOO manufacturer profile
Official Manufacturer Sources
Independent AirAlign engineering page. Device-specific maker photo and current exact-variant third-party approvals require separate verification.
FS51/FS52 — vane flow switch and pipe diameter
FS51 and FS52 use vane/paddle actuation in approved liquid lines, meaning the switching point depends on pipe bore, fluid conditions and how the paddle intersects the moving water. Choose the intended paddle and mounting fitting by manufacturer size table; a generic switch across multiple pipe diameters does not promise one common trip volume flow. Protect the vane from particulates and mechanical damage, and check discrete relay/limit-switch rating for pump flow proving.