The KOBOLD M-series is a magnetic float level switch that monitors and controls liquid levels in tanks, boilers, and containers. A float carrying a ring magnet slides along a guide tube and actuates a hermetically sealed reed contact without touching it, leaving the float as the only moving part. Every unit is built to customer specification, and one switch can supervise as many as four level points.
How the M-series switch works
A hermetically sealed reed contact sits inside the guide tube. As the liquid rises or falls, the float and its ring magnet travel along the tube and switch that contact by magnetic field alone. Contacts are supplied as normally open, normally closed, or changeover, and a single float can operate two contacts.
Pressure and temperature ratings
The M-series operates at a maximum medium temperature of 302°F (150°C) and a maximum pressure of 1450 psi (100 bar), with the exact limits set by the chosen float and guide tube. Stainless steel builds reach the higher ratings, while PVC, PP, and PVDF builds carry lower limits.
- M06 solid PP float: up to 1450 psi (100 bar), 194°F (90°C)
- M10 and M11 stainless steel ball floats: up to 435 psi (30 bar), 302°F (150°C)
- M08 stainless steel float: up to 290 psi (20 bar), 302°F (150°C)
- M13 PVDF float: up to 29 psi (2 bar), 257°F (125°C)
- M03 and M07 PVC-U floats: up to 43 psi (3 bar), 131°F (55°C)
Wetted materials and float designs
Wetted parts are available in stainless steel 1.4404, brass, PVC, PP, NBR, and PVDF, so the switch can be matched to the process medium. Thirteen float designs, models M01 through M20, cover cylinder and ball forms in outside diameters from 0.71 in (18 mm) to 3.74 in (95 mm). Minimum liquid density ranges from 0.5 to 0.9 depending on the float.
Process connections and mounting
Process connections include G⅛, G⅜, G½, G1, G1½, and G2 threads, 1 inch, 1½ inch, and 2 inch NPT, a PG7 male thread, and DIN and ANSI flanges, plus special connections on request. The switch mounts vertically within ±30 degrees and can be fitted from the top or the bottom of the vessel.
When the unit is fitted in the bottom of a vessel, the contact action reverses. The guide tube must not be bent or subjected to hard impact, since this can damage the internal reed contact.
Electrical contacts and connection heads
Contacts are rated 230 V AC/DC, 0.5 A, 10 VA on models M01 through M04 and 230 V AC/DC, 1 A, 60 VA on models M05 through M20. Connection heads are offered in aluminum, polyamide, polypropylene, and ABS, with ingress protection to IP65 on models fitted with a head.
Contact protection relays are available and are recommended when switching inductive loads such as solenoid valves.
Hazardous-area (ATEX) versions
ATEX-certified versions are available for gas and dust explosion-hazard areas, category 1G/D, marked Ex ia IIC T6 Ga and Ex ia IIIC T85°C Da for an ambient range of -20°C to +60°C. The intrinsically safe version carries a rated voltage Ui of 40 V, and installation must follow the hazardous-area instructions.
Important Notice: Transitioning to U.S. Manufacturing
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. Not all products can/will be reshored. During this transition, stock availability may fluctuate between the time of quotation and purchase order placement. We appreciate your patience as we work to establish our domestic supply chain and remain committed to providing you with the same high-quality products made closer to home.
Common Questions about M - Magnetic Level Switches
Ratings depend on the selected float and guide tube. The highest medium temperature is 302°F (150°C), reached by stainless steel floats, and the highest pressure is 1450 psi (100 bar), reached by the solid PP M06 float. PVC and PP builds carry lower limits.
Wetted parts are offered in PVDF, PVC, PP, NBR, brass, and stainless steel 1.4404. Thirteen designs span models M01 to M20 as cylinders and balls. Float sizes run 18 mm to 95 mm (0.71 in to 3.74 in) across the range, and the required specific gravity sits between 0.5 and 0.9.
Thread sizes run from G⅛ to G2. NPT is available in 1, 1½, and 2 inch, alongside a PG7 male thread. Flanged builds use DIN and ANSI patterns, and special connections are supplied on request to suit the tank fitting and float diameter.
A single M-series switch monitors as many as four switch points on one guide tube. On most floats, one float operates two contacts; the solid M06 float requires a separate float for each point. Contact positions L1, L2 and onward are measured from the sealing edge.
Contacts are configured as N/O, N/C, or changeover. Models M01 to M04 carry 230 V AC/DC, 0.5 A, 10 VA (changeover 100 V AC/DC, 0.5 A, 3 VA); models M05 to M20 carry 230 V AC/DC, 1 A, 60 VA. Treat these as absolute maximum values for resistive loads.
Connection heads are made from aluminum, polyamide, polypropylene, or ABS. Ingress protection is IP64 on models M01 to M04 and IP65 on models M05 to M20, and IP65 on any model fitted with a head. A one meter PVC or silicone cable is available on cable versions.
Yes. ATEX-certified builds cover gas and dust explosion-hazard zones in category 1G/D, carrying the markings Ex ia IIC T6 Ga and Ex ia IIIC T85°C Da, rated for ambients of -20°C to +60°C. Its intrinsically safe input is rated Ui = 40 V. Follow the hazardous-area installation instructions.
The code adds, in order, the guide tube material (E stainless, M brass, P PVC, S PVDF), the process connection, one contact function per point (S = N/O, C = N/C, W = changeover, X = none), an electrical option (0 housing; P, S or L cable; Y special), and an ATEX digit (0 or E). Letters read from the top point down.
Each float sets a minimum specific gravity, between 0.5 and 0.9, that the medium must exceed. The unit serves only level control and monitoring of liquids that are free of suspended solids and do not tend to crystallize. Verify chemical resistance of the wetted parts before selecting a build.
Mount the switch upright, deviating no more than ±30 degrees, and allow the float to move freely with clearance from the vessel walls. It can sit at the top or the bottom, and bottom mounting reverses the contact action. Keep the unit clear of strong magnetic fields for correct switching.
Product Specifications
Wetted Materials
Stainless Steel, Brass, PVC, PP, NBR, PVDF
Fittings
G ⅛, G ⅜, G ½ ,G 1, G 1½ G 2, 1" NPT, 1½" NPT, 2" NPT, PG 7 Male, DIN & ANSI Flanges
Connection Box
Aluminum, Polyamide, Polypropylene, ABS
Max. Temperature
302 °F (150 °C)
Product Features
Long Electrical Service Life
High Degree of Operational Reliability
Wide Range of Connections and Electrical Terminal Boxes
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Common M Series Questions