GF Signet 525 Metalex Paddlewheel Flow Sensor

316 SS insertion paddlewheel for elevated pressure/temperature liquid service (to 103 bar / 149 °C class) with self-powered frequency output.

Key advantages

High P/T capability — up to 103 bar (1500 psi @ SF 1.5) and 149 °C (300 °F) with socket-weld/mini-tap fittings.
Self-powered — frequency output for battery totalizers (e.g. GF 8150) and Signet instruments.
DN15…DN300 — mini-block, mini-tap, or saddle fittings for steel lines.
Wear pair — tungsten-carbide or SS shaft with CFR-PTFE bearings; 17-4PH rotor.

Typical applications

Boiler feedwater, HVAC, chemical transport, heat exchangers, RO, cooling systems.
Not suitable for gases (OEM note).

Selection guide

Velocity / pipe — 0.5…6 m/s (1.6…20 ft/s); DN15…DN300 (½…12 in.); min Re 4500.
Accuracy — Linearity ±1% of max range @ 25 °C; repeatability ±0.5% of max range @ 25 °C.
Electrical — ~39 Hz per m/s; amplitude 5…8 mV p-p per Hz; source impedance 11.6 kΩ; cable 7.6 m (to 61 m).
Materials — 316 SS body; 17-4PH rotor; WC or 316 SS shaft; CFR-PTFE bearings; KLINGER sil C-4401 gasket with fitting.
P/T — Socket-weld/mini-tap: 103 bar @ 149 °C; strap-on saddle: 21 bar @ 66 °C; operating −18…149 °C.
Hosts — Compatible with GF 8150 / 9900 / 9950 family per datasheet overview.

Common mistakes

Using saddle fittings at pressures only the weld/mini-tap rating supports.
Expecting open-collector powered output — 525 is self-powered mV-level frequency.
Applying on gases.
Operating below 0.5 m/s.
Flow instruments · Flow buying guide

When to RFQ / what to tell us

Pipe size/schedule and fitting style (mini-block / mini-tap / saddle).
Operating pressure and temperature; fluid (liquid only).
Host instrument; shaft preference (WC vs SS); quantity; ship-to.

Request a Quote · Get selection help

Specs

Spec	Value
SKU	20199
Brand	Georg Fischer / GF Signet
Model	525 Metalex
Product type	stainless steel paddlewheel flow sensor
Measuring range	0.5 to 6 m/s (1.6 to 20 ft/s); pipe DN15 to DN300 (½ to 12 in.)
Accuracy	Linearity ±1% of max range @ 25 °C; repeatability ±0.5% of max range @ 25 °C
Output signal	Self-powered frequency (~39 Hz per m/s; 5–8 mV p-p per Hz)
Supply voltage	Self-powered (no external sensor power)
Process connection	Mini-block / mini-tap / saddle fitting program for steel lines
Wetted materials	316 SS body; 17-4PH rotor; WC or 316 SS shaft; CFR-PTFE bearings
Media temperature	−18 to 149 °C (0 to 300 °F)
Max pressure	Up to 103 bar @ 149 °C (socket-weld/mini-tap); saddle 21 bar @ 66 °C
Notes	Values aligned with GF datasheet 3-0525.099 Rev L 06/2026-A. Not for gases.

Documents

GF Signet 525 Metalex datasheet (PDF)

FAQ

Q: 525 vs 2540? A: 525 is self-powered Metalex for higher P/T (to 103 bar / 149 °C) from 0.5 m/s; 2540 is powered OC frequency with low-flow to 0.1 m/s and hot-tap options.

Q: Which fitting for 100 bar service? A: Use socket-weld or mini-tap ratings — saddle fittings are limited to 21 bar @ 66 °C.

Q: What should I send for a quote? A: Pipe size, fitting style, P/T, fluid, host, quantity. Compatible with systems using GF Signet 525 if you need a drop-in check — we do not claim authorized-dealer status.