Flow Switches

The Dwyer - FST1001A is a Flow Switch featuring Economical, Air, 0 FPM to 5000 FPM, 2 SPST N.O Relays, 1/4 ", Compression Fitting, ± 2 % Accuracy, 304 SS, 12 " Wire L, and Fixed Probe. Part of the FST1000 Series. Sold individually.

The KOBOLD S-Series float type flow switch delivers reliable flow monitoring for water and air in a uniquely compact design that eliminates the typical open conical measuring tube in favor of an innovative cylindrical control tube with a conical groove along its axis. This economical yet robust solution provides flow-dependent operation with ±5% full scale accuracy while offering impressive pressure handling capabilities—up to 3600 PSIG for brass units and 5000 PSIG for stainless steel models—making it suitable for demanding industrial applications. Available with brass or 304 stainless steel housing and various float material options including polypropylene and PVDF for enhanced chemical compatibility, the S-Series accommodates water flow ranges from 0.075 GPM to 14 GPM (or air from 0.2 SCFM to 70 SCFM) with minimal pressure drop. The cCSAus approved reed contact system offers versatile switching configurations including normally open, SPDT, or dual contact options with ratings up to 240 VAC/0.42 A/100 W, all housed in a NEMA 4X/IP65 enclosure for environmental protection. Designed for vertical flow installation (bottom to top), this space-saving instrument integrates easily into process systems with standard NPT connections, providing continuous protection against equipment damage from excessive or insufficient flow conditions.

The Dwyer - FS-100-100 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 1 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.

The Dwyer - FSW-42A-SS is a Flow Switch for 3 " to 10 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, EPDM, FKM, and PTFE. Part of the FSW-40A Series. Sold individually.

The Dwyer - FSW-6212 is a Flow Switch featuring Thermal Dispersion, Liquid 0.09 FPS to 9.84 FPS, Gas 0.16 FPS to 49 FPS, 5 A SPDT, 3/4 ", NPT Male, ± 10 % Accuracy, 316 SS, and 2 " Insertion L. Part of the FSW-6000 Series. Sold individually.

The Dwyer - FSW303 is a Flow Switch featuring Low Cost, Economical, Liquid, 1.8 GPM to 2.4 GPM, 26 VA SPST, 3/4 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.

The innovative KOBOLD SMN Flow Switch delivers exceptional performance with its ability to detect extremely low liquid flow rates while maintaining minimal pressure drop during high-volume operation, making it ideal for critical process monitoring applications. Unlike conventional designs, this ingenious device utilizes a magnetic float suspended in a cylindrical tube that works against a compression spring, activating an adjustable reed contact when flow reaches the predetermined threshold. Available in brass construction rated to 3600 PSIG or stainless steel rated to an impressive 5000 PSIG, the SMN provides reliable switching between 0.4-13 GPM (on) and 0.25-1 GPM (off) while operating in temperatures up to 212°F. The NEMA 4X/IP65 rated housing with DIN 43650 connection ensures dependable performance in demanding industrial environments like cooling circuits, high-pressure cleaning systems, and contaminated media control applications. Featuring vertical or horizontal mounting flexibility and CSA-approved electrical options including standard N/O or optional SPDT contacts, this compact flow monitor combines precise low-flow detection with remarkable high-flow handling capability in a single, maintenance-friendly package.

The Dwyer - FSW-40A is a Flow Switch for 1 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.

The KOBOLD SV float type flowmeters and flow switches combine the proven variable area principle with innovative cylindrical control tube technology featuring a conical groove design that eliminates the need for traditional open measuring tubes while maintaining exceptional ±5% full scale accuracy. Housed in a lightweight, gold-anodized aluminum body with borosilicate glass metering tube, these versatile instruments provide clear visual flow indication with direct reading scales calibrated for either water (GPM) or air (SCFM) across an impressive range from 0.075 GPM to 40 GPM for liquids and 0.5 SCFM to 150 SCFM for gases. Available in three configurations—flowmeter only, flowmeter with single N/O contact, or flowmeter with dual N/O contacts—the SV series accommodates diverse monitoring requirements while offering flexible float material options including polypropylene, PVDF, nickel-plated brass, or stainless steel to match specific application chemistry and temperature demands. The robust construction features vertical NPT connections from 1/4" to 1-1/4" with nickel-plated brass or 304 stainless steel process connections, handling pressures up to 145 PSI and temperatures to 212°F (158°F with plastic floats) while maintaining cCSAus approved switching capabilities with ratings up to 240 VAC/100 W. With IP65 electrical protection and hermetically sealed reed contacts providing reliable switching with optional SPDT functionality, these compact instruments deliver maintenance-free operation ideal for process monitoring, alarm applications, and automated control systems requiring both visual indication and electrical output signals.

The Dwyer - FSW302 is a Flow Switch featuring Low Cost, Economical, Liquid, 0.9 GPM to 1.1 GPM, 26 VA SPST, 1/2 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.

The KOBOLD TWR bi-metal temperature switch provides reliable thermal protection and control for liquid systems with its robust, position-independent design that installs directly into pipes or tanks via a standard 3/4" NPT connection. Featuring factory-calibrated setpoints available in twelve discrete temperature thresholds ranging from 86°F to 248°F (30°C to 118°C), this compact unit delivers consistent thermal switching with ±9-13°F accuracy and up to 36°F hysteresis—making it ideal for both simple alarm applications and paired thermostatic control of heating and cooling equipment. Available in either nickel-plated brass or 304 stainless steel construction, the TWR withstands demanding process conditions including temperatures up to 248°F and pressures to 928 PSIG, while maintaining IP65 environmental protection for reliable operation in industrial environments. The versatile electrical interface features a convenient DIN 43 650 plug connection with optional integrated visual status indication—either LED illumination for DC circuits (up to 30VDC/1A) or signal lamp for AC applications (up to 125VAC/1A)—providing at-a-glance operational feedback. With straightforward normally-open or normally-closed switching configurations handling up to 250VAC/30VDC at 4A (without signal lamp), this maintenance-free thermal switch delivers essential temperature monitoring and control without requiring complex wiring or programming.

The Dwyer - FST-211-R is a Flow Switch with Compact Relay Controller featuring Liquid, 0.04 FPS to 3 FPS, 10 A SPDT, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, and PVDF. Part of the FST200R Series. Sold individually.

The KOBOLD VKG viscosity compensated flowmeter and switch offers revolutionary performance for monitoring high and low viscosity liquids with its patented compensation system that maintains accurate measurement (±5% full scale) despite significant viscosity fluctuations up to 540 cSt without requiring recalibration. Featuring a spring-loaded float design housed in a vibrant anodized aluminum body with borosilicate glass window, this versatile instrument provides reliable flow measurement for oils, water, and compatible liquids across a comprehensive range from 0.03 GPM to 21 GPM with minimal pressure drop. Available in multiple configurations—including standard flowmeter, flowmeter with one or two switching contacts, or with an additional side-mounted pointer indicator for dark fluids—the VKG adapts to diverse monitoring requirements while maintaining its universal mounting capability in any orientation. The robust construction with nickel-plated brass or stainless steel wetted components handles temperatures up to 212°F and pressures to 175 PSI, while density compensation up to 30 lbs/ft³ ensures measurement stability across fluid property variations. Equipped with cCSAus approved reed contact switches with various configuration options (N/O or SPDT) and IP65 environmental protection, this innovative instrument eliminates the traditional compromise between accuracy and fluid property changes, making it an exceptionally versatile solution for nearly any industrial liquid flow monitoring application.

The Dwyer - FS-100-500 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 5 GPM Switch Point, 50 VA SPST, 3/4 ", NPT Female, ± 10 % Accuracy, PP, and 12 " (300mm) Wire L. Part of the FS-100 Series. Sold individually.

The Dwyer - FST-221-R is a Flow Switch with Compact Relay Controller featuring Liquid, 0.04 FPS to 3 FPS, 10 A SPDT, 2 " to 12 ", NPT Male, ± 5 % Accuracy, PP, and PVDF. Part of the FST200R Series. Sold individually.

The Dwyer - FSW-31A is a Flow Switch featuring Non-Magnetic, Industrial, Water, 6 GPM to 70 GPM, 15 A SPDT, 1 ", NPT Female, Brass, 316 SS, Phosphor Bronze, EPDM, and PVC. Part of the FSW30 Series. Sold individually.

The Dwyer - FSW-50 is a Flow Switch for 1 " Pipe featuring Industrial, Liquid, 3.3 FPS to 11.5 FPS, 15 A SPDT, 1-1/4 ", NPT Male, 316 SS, Polyphenylene Sulfide, and FKM. Part of the FSW-50 Series. Sold individually.

The Dwyer - FSW-9112 is a Flow Transmitter featuring Liquid, 24 Vdc, 1/2 " NPT, Glass Filled Nylon with 1/2 " NPT Conduit, Cable Gland & 2 M (6.5 ') Cable, and 50 mm (2 "). Part of the FSW-9000 Series. Sold individually.

The FS8000 Series Inline Flow Switch from Madison Company is a high-performance, compact solution designed for accurate and reliable flow detection in demanding applications. Built with a clog-resistant, non-adjustable design, the FS8000 ensures consistent switching performance and minimal pressure drop, making it ideal for systems where flow precision and durability are critical. The Madison FS8000 is engineered to deliver dependable flow monitoring in compact spaces, where accuracy, ease of use, and maintenance-free operation are essential.

The Dwyer - FLCN-101 is a Sensor Controller featuring Single, Flow Alert, 3/4 " NPT, SPDT, PP (PP) Body, Calls Immediate Attention to Alarm Conditions, and Adjustable Time Delay Relay. Sold individually.

The Dwyer - FST-323-SPST is a Flow Switch featuring Thermal Dispersion, Gas, 1 FPS to 90 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 2 " to 12 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 ' Wire L. Part of the FST-320 Series. Sold individually.

The Dwyer - FST1002R is a Flow Switch featuring Economical, Air, 0 FPM to 10000 FPM, 2 SPST N.O Relays, 1/4 ", Compression Fitting, ± 2 % Accuracy, 304 SS, 12 " Wire L, and Remote Probe. Part of the FST1000 Series. Sold individually.

The Dwyer - FSW-32A is a Flow Switch featuring Non-Magnetic, Industrial, Water, 4 GPM to 8 GPM, 15 A SPDT, 1 ", NPT Female, Brass, 316 SS, Phosphor Bronze, EPDM, and PVC. Part of the FSW30 Series. Sold individually.

The Dwyer - FSW-51 is a Flow Switch for 1-1/2 " to 2-1/2 " Pipe featuring Industrial, Liquid, 2.7 FPS to 10.8 FPS, 15 A SPDT, 1-1/4 ", NPT Male, 316 SS, Polyphenylene Sulfide, and FKM. Part of the FSW-50 Series. Sold individually.