The KOBOLD NAB is a polypropylene float level switch that delivers mercury-free, high-current level switching for liquid tank applications, and it is designed for direct start and stop pump control. As the liquid level raises or lowers the float, the change in angle actuates an internal SPDT mechanical switch that can be wired normally open or normally closed. The NAB is rated IP68 and ships with a Neoprene jacketed, three-conductor cable in standard 10 ft or 30 ft lengths, with custom lengths available on request. Its high switch capacity allows many pumps to be controlled directly.
How the NAB Float Level Switch Works
The NAB is a float type, tilt level switch. Movement of the liquid tips the float, and the resulting angle change operates the internal mechanical contact. In a typical setup the switch activates near plus 55 degrees and deactivates near minus 55 degrees, although the exact angles depend on how the float is mounted and on cable length.
Float and Cable Materials
The float is built from industrial quality polypropylene (PP), paired with a Neoprene jacketed cable, and the assembly is rated to IP68. The switch contains no mercury. Neoprene is not recommended for certain highly corrosive or solvent based applications, so verify chemical compatibility with your process liquid before selecting the NAB.
Electrical Ratings and Wiring
The NAB uses an SPDT mechanical changeover contact, connectable as normally open (N/O) or normally closed (N/C). It switches up to 250 VAC at 50/60 Hz, with a maximum rating of 20 A for resistive loads and 8 A for inductive loads. The three cable conductors are colored blue, brown, and black.
Temperature, Pressure, and Media Density
The NAB carries a maximum temperature rating of 185°F (85°C) and a maximum pressure rating of 50 PSIG (3.5 bar). It is intended for liquids with a specific gravity from 0.7 to 1.15. These service limits should not be exceeded during operation.
Dimensions, Weight, and Cable Options
The float measures about 130 mm (5.12 in) in height with a diameter of Ø 70 mm (2.76 in). It weighs approximately 1 lb (0.45 kg) with the 10 ft cable and approximately 2.7 lbs (1.22 kg) with the 30 ft cable. An optional ballast weight (loaded resin, 175 g) is available and is ordered separately.
How to Order the NAB and Install It
The NAB is ordered by cable length, with an optional ballast weight available separately. The standard order codes are listed below, and longer cable lengths can be arranged through the factory.
- NAB-W03: conical float with 10 ft Neoprene cable
- NAB-W10: conical float with 30 ft Neoprene cable
- NAB-BALLAST: optional ballast weight
During installation, keep the cable ends out of the water at all times, because water can leak into the device through the cable. Confirm that the supply voltage matches the switch rating, do not exceed the specified switching capacity, and protect the cable joint with a suitable terminal box against contact and humidity. The NAB is almost maintenance free; inspect the cable periodically and replace a switch whose cable is damaged.
Common Questions about NAB - Polypropylene Float Level Switch
The NAB is a tilt style float switch. When rising or falling liquid tilts the float, that shift in angle trips a mechanical contact inside the body. The contact changes state at roughly 55 degrees of tilt from level in each direction, so the switching point shifts with the installation.
The NAB withstands up to 185°F (85°C) and 50 PSIG (3.5 bar), and it works with liquids of 0.7 to 1.15 specific gravity. Operating the switch beyond these temperature, pressure, or density limits falls outside its rated specification.
Yes. The NAB uses an SPDT changeover contact that can be set for normally open or normally closed operation. Its three conductors, colored blue, brown, and black, let you wire the switching function your pump or alarm circuit needs.
The NAB handles a supply of 250 VAC at 50/60 Hz. Its contact is rated 20 A on resistive loads and 8 A on inductive loads. This high current rating allows direct control of many pumps, so an interposing relay is often unnecessary.
The float is industrial quality polypropylene (PP) and the cable is Neoprene jacketed with three conductors, rated IP68, and the unit carries no mercury. Neoprene has media limitations, so confirm the cable material suits your liquid before installing the switch in aggressive service.
The NAB comes with a Neoprene jacketed cable in either a 10 ft or 30 ft standard length. If your installation needs more reach, longer cable lengths can be supplied on request by consulting the factory. The three conductors suit the SPDT changeover contact.
Each NAB float stands roughly 130 mm (5.12 in) high and Ø 70 mm (2.76 in) across. Weight is close to 1 lb (0.45 kg) on the 10 ft version and close to 2.7 lbs (1.22 kg) on the 30 ft version.
Order by cable length. NAB-W03 provides a 10 ft Neoprene cable and NAB-W10 provides a 30 ft cable, while NAB-BALLAST adds the optional ballast weight. For more reach than the standard options, request a custom cable length from the factory.
Product Specifications
Wetted Parts
Polypropylene (PP), Neoprene®
Max. Temperature
185 °F (85 °C)
Max. Pressure
50 PSIG (3.5 BAR)
Max. Switch Rating
250 VAC 50/60 Hz, 20A Resistive/8A Inductive Load
Product Features
Low Cost, High Value Tilt Switch
Heavy-Duty Industrial Design
Polypropylene Float, Neoprene® Jacketed Cable
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