Diesel- and oil-resistant variant of the K Series — same compact 75 mm tilt-action float, but with orange polyurethane cable made for single point level control in oils. NOT suitable for water or sewage applications.
KU Series
Float Switches
Features
- For diesel and oil applications (not water or sewage)
- Robust double moulded construction
- Orange polyurethane 3-core cable
- Polypropylene housing
- Low switching differential
- All directional tilt action
- Stable repeatable switching
- Compact size, 75 mm diameter
- Optional cable weight available
- Cable lengths 1–20 m (1 / 4 / 6 / 10 / 20 m)
- 30 m maximum submergence, 60 °C maximum liquid temperature
The KU Series uses the same 45° tilt-action float as the K Series, but with specially manufactured three-core orange polyurethane (H05BQ-F) cable. It is a compact three-wire float switch designed for single point level control in oils, and its ability to withstand oils makes it suitable for level control in diesel fuel tanks and in applications involving bulk diesel or oil. A heavy ball balanced on the actuating arm of a high precision switch moves away from the switch axis as the float tilts, so the float only has to tilt 45° in any direction for the switch to operate. Polypropylene float with a double-moulded, hermetically sealed chamber and a double-moulded barrier of solid polypropylene sealing the cable entry; load current is limited to 6 A by the 0.75 mm² cable. Operate only at low voltage (12–48 V AC or DC) for safety.
More Information
Select Model
Trade customers should contact sales@kelco.co.nz for account pricing.
Ordering — Available Models
| Model Number | Description |
|---|---|
| KCW-PE | |
| KU10M | KU Series float switch — 10 m of polyurethane cable (most common) |
| KU20M | KU Series float switch — 20 m of polyurethane cable |
| KU4M | KU Series float switch — 4 m of polyurethane cable |
| KU6M | KU Series float switch — 6 m of polyurethane cable |
Operating Limitations
| Maximum submergence | 30 m / 300 kPa static pressure |
|---|---|
| Maximum liquid temperature | 60 °C |
| Minimum liquid temperature | -20 °C |
| Liquid specific gravity | Greater than 0.8 |
| Liquid pH range | 1 to 14 |
| Smallest tank diameter | 300 mm inside diameter |
| Liquid level change for switch operation | 75 mm |
| Closest switching point to tank floor | 100 mm |
| Minimum distance from float to closest tether/weight | 200 mm |
Electrical Data
| Switch type | Single pole double throw (S.P.D.T.), silver alloy contacts, 0.5 mm gap |
|---|---|
| Contact resistance | 15 milliohms maximum (initial) |
| Rated voltage (switch contacts) | 125, 250 and 500 VAC; 8, 14, 30, 125 and 250 VDC |
| Operating voltage (safety note) | Only ever operate at low voltage: 12–48 V AC or DC |
| Resistive AC current rating | 15 A at 250 VAC, 15 A at 125 VAC (10 A at 500 VAC) |
| Motor load AC current rating | NO 2.5 A / NC 5 A at 125 VAC (⅛ HP); NO 1.5 A / NC 3 A at 250 VAC (¼ HP) |
| Resistive DC current rating | 15 A at 8 and 14 VDC, 6 A at 30 VDC, 0.5 A at 125 VDC, 0.25 A at 250 VDC |
| Maximum lamp load AC | NO 1.25 A / NC 2.5 A at 250 VAC |
| Maximum lamp load DC | NO 1.5 A / NC 3 A at 30 VDC |
| Minimum operating load | 160 mA at 5 VDC |
| Low-current inputs | The 160 mA at 5 VDC minimum is the microswitch manufacturer’s rating for guaranteed contact at very low currents. KU Series switches are also used on PLC, BMS and 24 VDC control inputs. For a dedicated low-current signal input, the KP-10 reed probe and the L-L side-entry switch (gold contacts) are designed for that duty. |
| Maximum operating frequency, electrical | 20 operations per minute |
| Dielectric strength between contacts | 1000 VAC, 50/60 Hz for 1 minute |
| Dielectric strength to ground | 2000 VAC, 50/60 Hz for 1 minute |
| Insulation resistance | 100 megohms minimum (at 500 VDC) |
| Mechanical life expectancy | 10 000 000 operations minimum |
| Electrical life expectancy | 500 000 operations minimum |
| Approved standards | UL1054 E41515, CSA C22.2 No. 55 (File No. LR21642) |
| Product load current | 6 A maximum (limited by the 0.75 mm² cable) |
Dimensions
Diesel & Oil Service Only
The KU is built specifically for oil and diesel service — the polyurethane cable resists swelling, hardening and cracking in diesel and oil. It is intended for use in oil and diesel applications only and is NOT suitable for use in water or sewage applications; use a K Series for those.
Typical Applications
Diesel fuel and oil tanks; high and low level alarms; alarms, pump control (direct or through a contactor or relay), and PLC / BMS inputs.
Safety — Low Voltage Only
In the interests of safety the KU Series should only ever be used with control voltages in the range of 12 to 48 volts AC or DC. All electrical work must be carried out by a qualified, licensed electrician in line with AS/NZS (or equivalent) standards and local wiring rules.
Hazardous Areas
The KU Series is not certified for use in hazardous areas and must not be installed in any area classified as hazardous under AS/NZS 60079.10 (Zone 0, 1, 2, 20, 21 or 22).
Operating Environment
Do not use the KU in closed vessels above 300 kPa static pressure or in submerged applications deeper than 30 m. Do not expose it to liquid temperatures below -20 °C or above 60 °C; the switch and cable will withstand temperatures outside these limits but service life may be reduced. In liquids of low specific gravity the buoyancy of the float is reduced and a proportionally higher operating differential results.
Mounting and Wiring
Avoid turbulence and any place where the float or cable will abrade against tank walls, piping or pumps, and keep the cables of adjoining switches from rubbing or tangling. Suspend the switch at least 100 mm away from tank walls and stand pipes. Never tie the float against a pipe or the side of the tank: it must be free to tilt and return to vertical. Keep exposed cable out of direct sunlight: terminate it in a junction box or run it in conduit rather than draping it over the tank rim. With the float hanging vertically the core colours are blue (common), black (normally closed) and brown (normally open); when the level rises and tilts the float 45°, blue to brown closes and blue to black opens. Most installations use only the blue common and one other wire; the unused wire is live when the switch actuates and must always be isolated. Two float switches controlling the high and low levels of a tank or pit normally use a latching circuit, for pumping out of or into the tank.
Cable Properties
H05BQ-F 3G0.75 mm² (KEMA-KEUR) cable: three cores of 22/0.2 mm copper, EPR insulation (2.4 ± 0.1 mm), core colours blue, brown and black, orange thermoplastic polyurethane (TMPU) outer sheath (RAL 2003), 7.25 ± 0.2 mm diameter, voltage rating 300/500 V, test voltage 2000 V / 2500 V, temperature range -50 °C to +90 °C fixed installation and -40 °C to +80 °C in motion, maximum conductor temperature 90 °C (200 °C short circuit), abrasion, cut and tear resistant, flexible at low temperatures, conductor resistance 26.0 Ω/km max. per core at 20 °C, cable current rating 6 A max. (cable limited), maximum suspended length approx. 50 m (cable only). Cable lengths available: 1, 4, 6, 10 and 20 m. The cable is also described as polyester-based, halogen-free, with high flexural fatigue strength, and resistant to oils, fats and mild acids.
Serviceability
Sealed unit — not user-serviceable internally. Spare cable lengths available from Kelco Engineering or your distributor.
