S3U Series Threaded Fuel or Water Tank Sensor - 17"

Wema's SSS/SSL, S3U/S3, and S5U/S5 stainless steel liquid level senders all perform the same function, and differ only in their mounting configurations.
These versatile stainless steel tank level senders can be used in diesel, water, gasoline, and hydraulic or other oils. (But not waste tanks.)

• SSS/SSL senders have a basic non-threaded SAE 5-hole pattern, and typically mount with a gasket seal and screws
• S3U/S3 senders have a 1.25" BSP threaded mount, and come in models for American (S3U) or Euro (S3) dashboard gauges, and mount with O-ring seals
• S5U/S5 senders have a 1.5" NPT threaded mount, and come in models for American (S5U) or Euro (S5) dashboard gauges

The 1-1/4" BSP threaded, S3U Liquid Level Senders in this entry have an American Standard Output Resistance❉ of 33 ohms when the tank is full, but have a BSP threaded mount so they can be used in European manufactured tanks – which typically have BSP threaded sender ports.
They are only suitable for use with matching 33 ohm "American" style dashboard gauges.

A typical use might be if you have a European manufactured boat, but want to switch to American dashboard gauges.

The S3U sensor has an NBR float which rises and falls on the central shaft along with the level of liquid in the tank.
The sensor unit is fully insulated to protect against dangerous electric currents inside the tanks.
This is an extremely important safety feature, because it protects against electrolytic corrosion, as well as the danger of an explosion when used with gasoline.

The S3U sensor has 1.25" BSP - straight male British pipe - threads that seal with an O-ring.
If necessary, you can use this sensor with a threaded Top Adapter (FL-2WE) (see Related Products, below) which will bolt to either a standard American SAE 5-hole mount (2.125" bolt circle), or the larger European 5-hole mount pattern, on your tank.

The sending unit length is measured from the top of the threads to the tip of the gauge.
It should be at least 1" less than the depth of a plastic tank, and 3/4" less than the depth of a metal tank.*
If the top of your metal tank flexes, deduct one (1) inch from the depth (like a plastic tank).

• For use with diesel, gasoline, oils or water
• Available in Imperial measurements in 1" increments from 4" to 60". (Metric lengths available from 500mm to 1050mm – see S3 BSP Threaded Senders.)
• Sensor electrical resistance range is 240 Ohms (empty tank) through 33 Ohms (full tank) (Standard American aftermarket)
• Standard resolution of KUS level senders is 12-21mm (0.47"-0.83"); so you will get a discrete step reading approximately every 1/2"-3/4" of liquid level
• Suitable for mounting in European manufactured tanks
• Can be used with any Wema System Dash Gauge with the same resistance (Ohm rating)
• Simple, reliable and accurate reed-switch/magnetic field design. The float is the only moving part, minimizing potential mechanical failures
• All 316 stainless steel with NBR (Nitrile Butadiene Rubber) float (float diameter = 1.38" [35mm])
• Includes 38mm and 43mm O-rings for sealing
• Operating Voltage: 12/24V DC
• NBR mounting gasket (1Pc) and screw (5Pcs) included
• Custom lengths and liquid level resolutions can be special ordered

❉ American Standard Output
Standard American gauges and senders are designed to work with a variable resistance from 240 ohms empty to 33 ohms full, while European products are designed to work with a variable resistance from 0 ohms empty to 180 ohms full.
Senders and the dashboard gauges they are paired with must have the same resistance range.
The American Standard Output is non-linear and is based on American Boat and Yacht Council standards with plus or minus 5% tolerance for range difference.
Resistance readings at different levels are as follows:
• 33 ohms at 100% 
• 67.5 ohms at 75%
• 105 ohms at 50% 
• 142.5 ohms at 25% 
• 240 ohms at 0%


* Note – Fastener torque setting for mounting these (O-ring sealed senders) to metal tanks is 9 +/- 1 Nm; plastic tanks is 7 +/- 1Nm