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S291 Capacitance Type Coolant Level Switch With Complimentary (Flip/Flop) Voltage Output

Coolant Level Switch providing complimentary voltage outputs. Fitted with integrated Delphi Metri-pack 150 series 4 pin connector.

TheS291is an active device designed to give an alarm signal if liquid falls below, or rises above, a preset level. It can be specified with a delay to eliminate false alarms due to turbulence.Containing a factory programmable microprocessor, the switch provides a complementary voltage output on two pins.

Its small footprint with limited intrusion into the tank means a reduced risk of damage and a wide range of customer specifiable options make it suitable for most applications.The switch is designed to operate in both earthed metal and isolated plastic tanks. For high accuracy the S291is ideally mounted horizontally at the point where an alarm or control signal is required. However, the switch can be mounted vertically –contact Fozmula with your application requirements

Data Sheet
Troubleshooting Guide

Liquid types

Water based liquids such as coolant or washer fluid.

Electrical rating

Supply voltage: 5±0.25 VDC.
Supply current: 5mA + source output.
Alarm delay time: 0 to 25s rising or falling(factory set).
Connection: 4 way Delphi Packard Metri-Pack 150 series connector.
Power up delay: 0to 10 s(factory set).
Power up state: ‘In Liquid’ or ‘Out of Liquid'(factory set).
Output type: Voltage (Complementary).

Output state in liquid* (Pin A): 4±0.25 VDC.
Output state in air* (Pin A): 0.5±0.25 VDC.
Output current (Pin A): 10 mA maximum.
Output state in liquid* (Pin B): ↔0.5±0.25 VDC.
Output state in air* (Pin B): ↔4±0.25 VDC.
Output current (Pin B): 10 mA maximum.

Environmental Ratings

Ingress: IP67(with mating connector fitted).
Max. pressure: 5.0 Bar (72 psi)
Temp. range: -40°C to +125°C
Weight: 70g typical (dependent on thread size)
EMC: ISO13766:2006


Body: Brass.
Probe: PTFE.
Terminals: Brass, Tin Plated.
Seals: EPDM & FVMQ.
Connector: PA66 30% Glass Filled Nylon.
Thread sealant: Vibra-Seal 516 (taper thread variants only).
Vibration (15.3Grms): 3 orthogonal planes for 3 hours per plane
Testing performed in accordance with BSEN 60068-2-64:1993
Drop: 1 m to concrete surface.


See diagram below.*Outputs are factory selectable; opposite states and alternative values from 0.5-4.5 VDC are available on request.

Optional accessoriesC/K1

Packard Metri-Pack 150 series mating connector kit to suit harness wire cross sectional area of 0.8 to 1.0mm2and sleeve Ø1.60 to 2.15mm.

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