Flow Switches

The Dwyer - FS-100-050 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 0.5 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 - FSW-160 is a Flow Switch featuring Paddle, Heavy Duty, Liquid, 4 GPM to 500 GPM, 15 A SPDT, 1 ", NPT Male, ± 1 % Accuracy, 316 SS, 304 SS, Brass, and EPDM. Sold individually.

The Dwyer - FST-321-SPST is a Flow Switch featuring Thermal Dispersion, Gas, 1 FPS to 90 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 ' Wire L. Part of the FST-320 Series. Sold individually.

The Dwyer - FSW301 is a Flow Switch featuring Low Cost, Economical, Liquid, 4 GPM to 132 GPM, 26 VA SPST, 1/2 ", NPT Male, Brass, SS, PP, and Noryl. Part of the FSW300 Series. Sold individually.

The Dwyer - FST-212-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.

The Dwyer - FS-100-025 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 0.25 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 versatile KOBOLD KSM Plastic Flowmeter delivers reliable flow measurement for aggressive chemicals and corrosive substances with its all-plastic construction featuring no metal components in the fluid path. Available with either durable Polysulfone (for highly corrosive applications) or Trogamid® measuring tubes (for moderately aggressive media), this variable area flowmeter provides ±4% full scale accuracy while withstanding pressures up to 145 PSI and temperatures to 140°F. The device's highly visible red PVDF float and large dual-scale display show both direct flow readings (GPM/SCFM) and percentage values, making monitoring simple across a wide measurement range from 0.06 to 264 GPM for liquids or 0.5 to 400 SCFM for gases. Optional bistable reed contact switches with IP65 protection can be easily added for automated flow control and alarm functionality, with convenient field-adjustable markers ensuring precise setpoint positioning. Featuring robust PVC connections (available in glue socket or NPT threaded options) and chemical-resistant EPDM seals, this shock-resistant instrument provides reliable service in water treatment, chemical processing, laboratory, and other demanding environments where metal flowmeters would quickly deteriorate.

The Dwyer - FSW-25 is a Flow Switch featuring Trim-to-Size, Paddle, Liquid, 43 Centistokes, SPDT, 1 ", PT, ± 1 % Accuracy, 304 SS, and Aluminum. Sold individually.

The Dwyer - FST-221-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 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-200 Series. Sold individually.

The Dwyer - FSW-42A 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, and EPDM. Part of the FSW-40A Series. Sold individually.

The Dwyer - FSW304 is a Flow Switch featuring Low Cost, Economical, Liquid, 3.5 GPM to 4.4 GPM, 26 VA SPST, 1 ", NPT Female, and Brass. Part of the FSW300 Series. Sold individually.

The Dwyer - FSW-41A is a Flow Switch for 1-1/2 " to 2-1/2 " 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 cutting-edge KOBOLD KAL-D Compact Thermal Flow Switch delivers reliable flow monitoring for water-based liquids through advanced calorimetric technology that requires no moving parts, ensuring exceptional performance even with particulate-laden fluids. Featuring microprocessor-based temperature compensation for precise measurement across varying conditions, this stainless steel instrument detects flow velocities from 0.15 to 6.6 ft/sec while providing field-adjustable setpoints via an intuitive LED bargraph display and potentiometer adjustment. The compact insertion-type design minimizes pressure loss while withstanding operating pressures up to 580 PSIG and temperatures from -4°F to 176°F, with clean-in-place capability up to 250°F for sanitary applications. Available with multiple connection options including NPT, BSP, and M12x1 threads, and configurable with either NPN or PNP transistor outputs in normally open or normally closed configurations, this versatile instrument adapts perfectly to diverse industrial requirements. Protected to NEMA 4/IP65 standards and constructed with premium 316L stainless steel wetted parts, the KAL-D offers exceptional durability alongside sophisticated electronic protection features including short-circuit safeguards for its 400mA switching capacity.

The Dwyer - FST-211-SPST is a Flow Switch featuring Thermal Dispersion, Liquid, 0.04 FPS to 3 FPS, 1 A SPST Relay, N.O/N.C, Selectable, 3/4 " to 1-1/2 ", NPT Male, ± 5 % Accuracy, PP, PVDF, and 10 " Wire L. Part of the FST-200 Series. Sold individually.

The Dwyer - FSW-30A is a Flow Switch featuring Non-Magnetic, Industrial, Water, 0.12 GPM to 8 GPM, 15 A SPDT, 1/2 ", NPT Female, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW30 Series. Sold individually.

The KOBOLD KAL-K thermal flow switch delivers exceptional monitoring performance for water-based liquids through advanced microprocessor-controlled technology with intelligent temperature compensation. Unlike conventional flow switches, this compact device maintains consistent readings across temperature fluctuations, making it ideal for applications requiring reliable flow monitoring in changing conditions. The robust design features no moving parts, making it extremely durable and insensitive to contaminants while providing remarkably low pressure loss in your system. With capabilities to handle flow velocities from 0.02 to 6.6 ft/sec and withstand temperatures up to 250°F and pressures to 1450 PSIG, the KAL-K offers versatility across numerous industrial applications.

The KOBOLD KAL-L thermal air flow switch delivers intelligent flow monitoring for non-hazardous gases with rapid response times and sophisticated temperature compensation achieved through a dual RTD design—one sensor detecting flow while the other monitors ambient conditions to prevent false alarms from environmental temperature shifts. This insertion-style unit, featuring a bright 8-digit LED bargraph flow indicator and adjustable response time (1-60 seconds), enables precise monitoring across a vast range of pipe diameters without requiring specific calibration for each application size—simply knowing your system's flow velocity is sufficient for proper implementation. The compact polyamide housing with nickel-plated brass sensor provides reliable performance in temperatures from -10°F to 250°F with pressures up to 120 PSIG, while offering adjustable setpoints through an accessible potentiometer and visual status indication via a two-color LED. With no moving parts to wear out or cause pressure drop, this solid-state monitoring solution maintains ±10% switching accuracy and exceptional ±1% repeatability across flow velocities from 3.3 to 66 ft/sec (capable of monitoring from 344 SCFM in 4" ducts to over 34,000 SCFM in 40" systems). Available with convenient mounting options including 1/2" NPT threads or 2-bolt flange connections, and electrical interface choices of conduit hub or quick disconnect with cable, the KAL-L delivers maintenance-free operation with IP65 environmental protection that makes it ideal for HVAC systems, ventilation monitoring, and other critical air flow applications.

The Dwyer - FST1001R 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 Remote Probe. Part of the FST1000 Series. Sold individually.

The Dwyer - FS-100-250 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 2.5 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 KOBOLD NKP level switch offers an affordable yet highly reliable solution for side-mounted liquid level detection in challenging chemical environments, thanks to its polypropylene or PVDF construction that stands up to aggressive media. Engineered with remarkable simplicity and functionality, this compact device features a magnetic float mechanism that delivers consistent performance with minimal maintenance requirements, making it ideal for long-term deployment in industrial applications. The versatile design allows for easy switch function conversion from normally open to normally closed by simply rotating the unit 180°, providing installation flexibility without additional components or reconfiguration. With NEMA 6/IP68 protection and hermetically sealed reed switch technology, the NKP maintains operational integrity even in harsh environments and can withstand pressures up to 145 PSIG and temperatures up to 212°F (PVDF version). Particularly valuable for vessels with limited top or bottom access, this side-mounting level switch combines practical engineering with excellent chemical compatibility to deliver dependable level control across a wide range of industrial applications.

The Dwyer - FSW-43A is a Flow Switch for 10 " to 48 " 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 PPS polysulfone paddle switch delivers cost-effective flow monitoring for pipes 1" and larger with exceptional reliability and virtually no maintenance requirements. Featuring a transparent housing that allows for visual confirmation of switch status via the visible red magnet bearer, this versatile device provides immediate operational feedback at a glance. With a temperature tolerance up to 225°F and negligible pressure drop during operation, the PPS performs efficiently in a wide range of industrial applications without compromising system performance. Installation is straightforward—simply insert into an appropriately sized tee fitting or NPT coupling with PTFE tape—while the trimmable paddle design allows for customization to match specific pipe diameters for optimal sensitivity and the lowest possible switching point. Available with normally open, normally closed, or SPDT reed switch configurations, this economical flow monitor combines durable construction with flexible application options while maintaining IP65/NEMA 4 protection for reliable service in demanding environments.

The KOBOLD PSR/PS paddle type flow switch delivers reliable liquid flow monitoring in a simple, economical package featuring an innovative bistable reed contact design with adjustable setpoints for precise control of process conditions. Using a clever mechanical design where flowing media deflects a paddle connected to a balance arm with pre-stressed leaf spring, the unit transmits movement to a permanent magnet that activates the hermetically sealed reed contact housed safely away from the process media. Available in robust brass construction (up to 1450 PSIG) or premium stainless steel versions (up to 3625 PSIG) with various NPT connection sizes from 1/4" to 1-1/2", these versatile units accommodate a wide range of pipe dimensions and flow requirements while maintaining ±15% switching tolerance. The PSR model is designed for direct installation in pipes from 1/4" to 1-1/2" NPT, while the PS version features extended paddles specifically engineered for larger diameter pipes from 2" to 8", with both versions offering cCSAus approved switching capabilities for critical safety applications. With straightforward field-adjustable switching points, easily configured normally open or normally closed operation, and IP65 environmental protection, these dependable units excel in cooling/lubricant circuits, pump dry-run protection, low water level detection, and pipe breakage monitoring without requiring external power.

The Dwyer - FS-100-200 is a Flow Switch for Threaded Plastic Piping featuring Liquid, 2 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.