Fuel/Water Sensor Threaded Stainless

The WEMA S3 Fuel and Water Sender is a high-reliability, vertical-style level sensor designed for the demanding environments of marine, RV, and industrial applications. Constructed from high-grade 316 stainless steel, this sender provides a robust alternative to traditional swing-arm units. It is compatible with a wide range of liquids, including gasoline, diesel, fresh water, and grey water.

Measurement Technology

The S3 series utilizes a magnetic reed switch system to ensure accurate and stable readings even in rough conditions. A float containing internal magnets moves vertically along the stainless steel shaft, activating a series of reed switches. This design eliminates the erratic needle movement often seen with mechanical arm senders as fuel sloshes in the tank. The electronics are fully encapsulated and insulated within the tube, protecting them from moisture and corrosion.

Mounting and Installation

The defining characteristic of the S3 model is its 1.25 inch BSP threaded head. This allows the unit to be screwed directly into a matching threaded tank port. For tanks without a threaded opening, various mounting flanges—such as the SAE 5-hole pattern adapter—can be used to secure the unit. Each sender is supplied with dual nitrile O-rings to ensure a liquid-tight seal upon installation.

Technical Specifications

• Material: 316 Stainless Steel for the shaft and head.

• Compatibility: Suitable for 12V and 24V DC systems.

• Resistance Ranges: Available in two industry-standard outputs:

  • American Standard: 240 ohms (Empty) to 33 ohms (Full).

  • European Standard: 0 ohms (Empty) to 190 ohms (Full).

• Resolution: Standard resolution features reed switches spaced approximately 20mm apart, while high-resolution versions are available with 10mm spacing for shallow tanks.

• Length Options: Available in a vast range of lengths, typically starting from 150mm (6 inches) up to 1600mm or more.

Accuracy and Maintenance

Because the only moving part is the float, the S3 sender is virtually maintenance-free and highly resistant to mechanical failure. To ensure the most accurate reading and prevent damage, it is recommended to select a sender length that allows for at least 1 inch of clearance from the bottom of the tank. The tinned wire leads are sheathed for additional protection against the elements, ensuring long-term electrical integrity.

R2026-3