KOBOLD SWK Compact Rotameter Flow Meter and Switch
The KOBOLD SWK is a compact variable area flow meter and switch, a spring-loaded rotameter that measures and monitors low flow rates of clean liquids. The float moves in the direction of flow against a spring inside a cylindrical guide tube, so no conical measuring tube is needed and the meter mounts in any orientation. A permanent magnet in the float operates an adjustable reed setpoint contact on the housing exterior, and indicator versions add an aligned pointer scale. The SWK suits low-flow monitoring where low cost and high reliability are priorities, in a brass, stainless steel, or PVC body.
How the SWK measures and switches flow
Inside a cylindrical flow tube, an aperture float rises against a spring as flow increases, and magnets in the float trip a potential-free reed contact that closes on rising flow above the set value. The contact is bistable, so it stays closed after the flow crosses above the adjusted limit.
On SWK-2 indicator versions, the same float movement drives an aligned pointer along a scale, giving a direct local reading of flow while the switch output continues to work.
Flow ranges, body materials, and connection
The SWK is supplied in eight switching ranges that together span 0.05 to 24 L/min of water, roughly 0.013 to 6.3 GPM, each with a G 1/2 female process connection. Body options are brass, stainless steel, or PVC, letting the meter be matched to the process liquid.
Repeatability is within ±2.5% of full scale on the contact and within ±4% on the pointer indicator.
Temperature and pressure ratings
Ratings depend on the body material. Brass and stainless steel versions are rated to 210 °F (99 °C) and 3600 PSIG (248 bar). PVC versions are rated to 140 °F (60 °C) and 85 PSIG (5.9 bar). These operating limits should not be exceeded in service.
Switch output and electrical connection
The standard output is a bistable, normally open reed contact (SPST) rated up to 230 VAC, 60 W. An optional changeover contact (option U) is available in place of the standard contact. The unit is wired out through a 3 ft (0.9 m) PVC cable, and enclosure protection is NEMA 4 / IP 65.
Models, indicators, and ordering
SWK-1 versions are switches with an adjustable setpoint, and SWK-2 versions include a pointer scale for local readout. The part number also encodes the body material and the flow range. PVC bodies are offered from the 0.2 to 0.8 L/min range upward, and the flowmeter-and-switch versions are available in brass and stainless steel.
Installation and maintenance
The SWK can be installed in any position. If flow is arranged from top to bottom, the switching range is displaced, so the mounting direction should be chosen with that in mind. Where ferrite particles may collect on the float, a magnet filter is recommended.
With clean media the meter is otherwise largely maintenance-free, and it should be cleaned if lime or other deposits build up.
Due to the ongoing implementation of EU Directive 2020/2184 that restricts brass materials, product availability is subject to change at any time. We are actively reshoring production of our brass flowmeter models to U.S. facilities to ensure continued supply.
Common Questions about SWK - Compact Flow Meters and Switches
A spring-loaded float sits in a cylindrical flow tube and lifts as liquid flow rises. A permanent magnet inside the float actuates an external reed contact, giving a fail-safe flow signal, and SWK-2 units also move a pointer along a scale for direct reading. No conical tube is needed.
The SWK comes in eight ranges of water flow, from 0.05 to 0.1 L/min at the low end up to 13 to 24 L/min at the top, about 0.013 to 6.3 GPM across the series. Each model covers one range, identified by the last digits of the part number.
Bodies come in nickel-plated brass, stainless steel, or PVC. Whichever body is chosen, the internal wetted parts include 301 stainless steel and ceramic, and stainless bodies also use 304 stainless steel. Material choice sets the temperature and pressure limits, and the liquid must not chemically attack the wetted parts.
Brass and stainless steel bodies handle up to 210 °F (99 °C) at 3600 PSIG (248 bar). PVC bodies are limited to 140 °F (60 °C) at 85 PSIG (5.9 bar). Pick the body material to match the service conditions of the application.
The standard contact is a bistable, single pole normally open reed switch that closes when rising flow passes the setpoint and holds closed above it. It is rated to a maximum of 230 VAC and 60 watt. An optional changeover contact is available where a transfer output is needed.
Every SWK uses a G 1/2 female thread at the process port. Electrical connection is via a PVC cable of 3 ft (0.9 m) fitted to the contact housing. The enclosure carries NEMA 4 and IP 65 protection against dust and water jets, so it can be used in demanding locations.
SWK-1 models are flow switches with an adjustable setpoint but no display. SWK-2 models add an aligned pointer indicator that shows the flow rate on a scale while still providing the switch signal. Both share the same operating principle, materials, and G 1/2 connection.
The number reads version, material, then range: the first digit after SWK is 1 for a switch only or 2 for a switch with indicator; the next digit is the body (1 brass, 2 stainless, 3 PVC); the final digits set the range. PVC is not offered on the two lowest ranges, and indicator models are brass or stainless only.
The SWK is designed for clean, low-viscosity, homogeneous liquids that do not chemically attack the wetted parts; a magnet filter helps where ferrite particles are present. It can be mounted in any position, though a top-to-bottom flow path shifts the switching range, so plan the direction accordingly.
The unit ships set at the lowest scale value. To change it, loosen the knurled nut, move the reed contact to the wanted mark, and retighten; SWK-2 units can be set using the pointer or a continuity tester. Switching hysteresis corresponds to about a 0.12 in (3 mm) float movement.
Product Specifications
Measuring/Switching Range
0.05...0.1 to 13...24 L/m
Body Material
Brass, Stainless Steel, PVC
Max. Temperature
212 °F (100 °C)
Product Features
Adjustable Switch or Switch with Indicator
Compact Size, Universal Mounting
Brass, Stainless Steel or PVC Body
BABA (Build America, Buy America) compliant models available
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