Kobold KAL-D5408RST3 – KAL-D Compact Thermal Flow Switch, 1/4″ NPT, PNP NC, Micro-DC Plug
The Kobold KAL-D5408RST3 is a compact thermal (calorimetric) flow switch from Kobold’s KAL-D series. It has a 1/4″ NPT process connection, a PNP normally closed transistor output, a 24 V DC supply and a 4-pin Micro-DC plug. Its wetted parts are 316L stainless steel.
This version combines the PNP (sourcing) output used by most European PLCs with a normally closed function, which is often preferred for monitoring and alarm circuits: the output goes to its open (alarm) state not only when flow is lost but also if the switch loses power. The KAL-D has no moving parts: its sensor tip is heated a few degrees above the liquid temperature, and the flowing liquid cools it in proportion to the flow velocity. When the flow reaches the field-adjustable setpoint, the output switches. A microcontroller compensates for changes in liquid temperature, and an 8-LED bargraph shows the flow trend and the setpoint.
Key Technical Data – Kobold KAL-D5408RST3
- Series: Kobold KAL-D compact thermal flow switch
- Measuring principle: Calorimetric, no moving parts
- Process connection: 1/4″ NPT
- Media: Water-based liquids (at least 90 % water); not suitable for oils or fuels
- Switching range: 0.15–6.6 ft/s (approx. 0.05–2 m/s)
- Repeatability: ±2 %
- Response time: 5.6–12 s typical
- Max. pressure: 580 psig (40 bar)
- Operating temperature: –4 to +176 °F (–20 to +80 °C)
- Wetted parts: 316L stainless steel; housing 304 stainless steel
- Power supply: 24 V DC ±10 %, max. 150 mA
- Output: PNP open collector, normally closed, max. 400 mA, short-circuit protected
- Setpoint adjustment: Potentiometer, flashing LED on 8-LED bargraph
- Status indicator: Dual-colour LED (red = alarm, green = flow)
- Electrical connection: Micro-DC plug, 4-pin male
- Degree of protection: NEMA 4X / IP65
Choosing the Right KAL-D Version
- KAL-D5408RST3: PNP normally closed (this item)
- KAL-D5408PST3: PNP normally open
- KAL-D5408NST3: NPN normally open
- KAL-D5408MST3: NPN normally closed
Other connections: KAL-D5415 (1/2″ NPT), KAL-D1408 (1/4″ BSP), KAL-D1415 (1/2″ BSP) and KAL-D0412 (M12 × 1). A mating 807.037 plug with 6 ft cable is available as an accessory. The output type and contact function must match the control circuit. Our sales team can help you confirm the right version.
Typical Applications
- Low-flow alarms in cooling water circuits
- Protection of pumps against dry running
- Water treatment and dosing systems
- Replacement switches for installed KAL-D systems
Buy Kobold KAL-D5408RST3 from Atlantech Drives
- Fast sourcing, shipped worldwide
- 12-month warranty
- Senior commercial advice on flow switch versions and lead time
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