GF Signet Measurement and Control Instrumentation

+GF+ (Georg Fischer) Signet measurement and control instrumentation is engineered for water treatment and corrosive-media service, with wetted materials available in PP, PVDF, 316 stainless steel, Hastelloy-C and titanium. These instruments form the measurement and feedback layer of a chemical dosing system. +GF+ is the principal instrumentation brand used in Dalian Roy Pump's packaged dosing skids and water treatment systems; we supply the +GF+ instrument range and take responsibility for sizing, sensor location design, signal integration and commissioning.

Flow Measurement

Paddlewheel Flow Sensors

Main series include 515, 525, 2536 and 2540. Paddlewheel sensors are simple, low-pressure-loss and cost-effective, and suit a wide range of pipe sizes when combined with the matching installation fittings. All four share the same ±0.5% repeatability and ±1% linearity; they differ in power supply and body material. The 515 and 525 are self-generating and need no external supply, giving a sine-wave frequency output; the 2536 and 2540 require 5–24 VDC and give an open-collector square-wave output. The 515 and 2536 have plastic bodies (PP / PVDF / PVC), while the 525 and 2540 use 316 stainless steel for markedly higher temperature and pressure ratings (the 525 reaches 149 °C and 103 bar).

Electromagnetic Flow Meters

With no moving parts and no pressure loss, magmeters are unaffected by viscosity or suspended solids. They are the preferred choice for wastewater, slurries and crystallising chemical solutions where paddlewheel sensors are unsuitable, and they run maintenance-free over long service periods.

Flow Transmitters

Local display of instantaneous and totalised flow, with 4–20 mA or digital output to PLC/DCS, supporting flow-proportional dosing, batch dosing and alarm functions.

pH / ORP Measurement

The system comprises helical or differential electrodes, a preamplifier and a transmitter. Differential electrodes use a three-electrode design with strong resistance to fouling and reference poisoning, delivering significantly longer service life than conventional combination electrodes in dirty, high-concentration dosing duty. The preamplifier boosts the high-impedance signal locally to allow longer cable runs. ORP is used to determine the dosing end point for oxidising and reducing agents.

Conductivity / Resistivity Measurement

Electrodes, sensor electronics and transmitters cover the full range from high-purity water resistivity to concentrated brine conductivity. In cooling water systems the signal monitors cycles of concentration and interlocks blowdown with corrosion- and scale-inhibitor top-up; in demineralised water systems it monitors product water quality and signals resin regeneration.

Level, Temperature and Pressure Sensors

Submersible and non-contact level sensors, level switches, temperature sensors and pressure sensors in corrosion-resistant materials, suitable for direct installation in chemical storage tanks and dosing lines. Level signals provide low-level alarm and pump-stop protection; pressure signals provide overpressure monitoring of the dosing line.

Free-Chlorine and Turbidity Analyzers

Free-chlorine analyzers provide online residual chlorine monitoring for drinking water plants, secondary water supply and disinfection processes, and can form a closed loop with sodium hypochlorite or chlorine dioxide dosing to hold residual chlorine within specification. Turbidity analyzers monitor effluent turbidity in coagulation and flocculation processes, providing a direct basis for evaluating coagulant performance and optimising dose rate.

Typical Roles in a Dosing System

Parameter	Typical Instrument	Function in the Dosing System
Flow	Paddlewheel / electromagnetic flow meter	Flow-proportional dosing against make-up or process flow; online verification of actual metering pump output
pH / ORP	pH/ORP electrode and transmitter	Closed-loop neutralisation control; end-point detection for oxidising and reducing agents
Conductivity	Conductivity electrode and transmitter	Cycles-of-concentration monitoring, interlocked with blowdown and inhibitor top-up
Level	Level sensor / level switch	Low-level alarm and pump-stop protection to prevent metering pumps running dry
Pressure	Pressure sensor	Overpressure alarm on the dosing line, working with back-pressure and relief valves
Free chlorine	Free-chlorine analyzer	Closed-loop disinfectant dosing to hold residual chlorine on target
Turbidity	Turbidity analyzer	Evaluation of coagulant/flocculant performance and dose optimisation

Selection and Integration

Instrument selection depends on media corrosivity, temperature, pressure, pipe size, measuring range and hazardous-area requirements. As a packaged dosing system manufacturer, Dalian Roy Pump integrates +GF+ instrumentation with Milton Roy metering pumps, solution tanks, agitators and pipework on a single skid, and completes signal wiring, PLC configuration and site commissioning in-house — avoiding the interface and responsibility gaps that arise when instruments and pumps are purchased separately. Contact us for detailed model data and selection support.