S3 Fuel and Water Sender
Wema S3 Fuel and Water Senders are tried and tested over millions of units, decades of use and in almost every kind of application.
These senders are reliable and accurate giving customers the confidence to depend on our technology year after year. Fitted as original equipment by major British and European boat builders for over 40 years, and trusted by commercial vehicle, defence and agricultural manufacturers worldwide.
Manufactured from 316 stainless steel, the S3 works on the simple principle of twin magnets in the float tripping a series of reed switches, securely housed and doubly insulated inside the stainless tube.
The sender is passive and draws power from the gauge.
They are available in lengths from 150mm to 1600mm. Longer and custom lengths are available on request, including calibrated senders for odd-shaped tanks.
There are two standard resistance ranges:
- 0-190Ω — European specification
- 240-30Ω — American specification
Sender and gauge must have the same resistance range — or the gauge will read backwards, or not at all. European vs American resistance →
Output from the sender is usually resistance but voltage options (0-5V, 0-10V, 4-20mA) are also available in some sizes and as a special order item. Special orders may be subject to a minimum order quantity depending on the modification — contact us to discuss your requirements.
If your current sender has a voltage output then you will have 3 wires not 2. Three or four wires could also mean that you have a sender with a high or low level alarm so it's always best to check the product code on the ID plate before ordering. How to identify your sender →
The S3 screws into a 1¼" BSP parallel thread.
Note: BSP sizing refers to the internal bore of a pipe — a 1¼" BSP thread measures larger than 1.25" with a tape measure.
If your tank has a 1.5" BSP, 1.25" NPT tapered thread or other fitting, you may need an adapter. We have many common flanges and thread adapters available. If unsure just ask.
Advancements in reed switch technology have allowed us to fit more switches inside the senders, giving the improved resolution required by modern digital displays.
For shallow tanks less than 400mm deep, high-resolution senders are available with approximately twice the number of switching points — a change of state approximately every 10mm instead of ~20mm in a standard resolution sender.
Wema S3 senders are suitable for diesel, petrol, fresh water, grey water, black water, hydraulic oil, AdBlue and ethanol.
Supplied with two nitrile O-rings for use in diesel tanks. If you are fitting to a petrol tank then Viton O-rings are recommended as ethanol content in modern fuels degrades nitrile over time. Viton O-rings available here →
The S3 can also be used as a position sensor by mounting the sender to a stationary part and clamping the float to a moving component. This is often used in industrial and agricultural machinery — a lifting trailer tailgate or a lifting keel on a yacht for example.
If you have an existing Wema sender, the identification plate on the head shows the product model, spec, length, Wema product code, output and batch code.
The code 001300 stamped on the head indicates an S3. How to identify a replacement Wema sender →
Specifications
- Fitting: 1¼" BSP parallel thread
- Material: 316 stainless steel
- Output: 0-190Ω / 240-30Ω resistance (standard), or 0-5V / 0-10V / 4-20mA (custom)
- Lengths: 150–1600mm standard
- Working voltage: 12V or 24V (draws power from gauge)
- Max carrying current: 1.2A
- Max switching current: 0.5A, 10W
- IP rating: IP65
- Operating temp: -40°C to +85°C
- Torque: 9 ±1 Nm (steel flange) / 7 ±1 Nm (nylon flange)
How long should your sender be? → | How to measure a level sender → | Replacing a floating-arm sender? →
[Please note: the code 001300 refers to the S3 head]
Wema S3 Fuel and Water Senders are tried and tested over millions of units, decades of use and in almost every kind of application.
These senders are reliable and accurate giving customers the confidence to depend on our technology year after year. Fitted as original equipment by major British and European boat builders for over 40 years, and trusted by commercial vehicle, defence and agricultural manufacturers worldwide.
Manufactured from 316 stainless steel, the S3 works on the simple principle of twin magnets in the float tripping a series of reed switches, securely housed and doubly insulated inside the stainless tube.
The sender is passive and draws power from the gauge.
They are available in lengths from 150mm to 1600mm. Longer and custom lengths are available on request, including calibrated senders for odd-shaped tanks.
There are two standard resistance ranges:
- 0-190Ω — European specification
- 240-30Ω — American specification
Sender and gauge must have the same resistance range — or the gauge will read backwards, or not at all. European vs American resistance →
Output from the sender is usually resistance but voltage options (0-5V, 0-10V, 4-20mA) are also available in some sizes and as a special order item. Special orders may be subject to a minimum order quantity depending on the modification — contact us to discuss your requirements.
If your current sender has a voltage output then you will have 3 wires not 2. Three or four wires could also mean that you have a sender with a high or low level alarm so it's always best to check the product code on the ID plate before ordering. How to identify your sender →
The S3 screws into a 1¼" BSP parallel thread.
Note: BSP sizing refers to the internal bore of a pipe — a 1¼" BSP thread measures larger than 1.25" with a tape measure.
If your tank has a 1.5" BSP, 1.25" NPT tapered thread or other fitting, you may need an adapter. We have many common flanges and thread adapters available. If unsure just ask.
Advancements in reed switch technology have allowed us to fit more switches inside the senders, giving the improved resolution required by modern digital displays.
For shallow tanks less than 400mm deep, high-resolution senders are available with approximately twice the number of switching points — a change of state approximately every 10mm instead of ~20mm in a standard resolution sender.
Wema S3 senders are suitable for diesel, petrol, fresh water, grey water, black water, hydraulic oil, AdBlue and ethanol.
Supplied with two nitrile O-rings for use in diesel tanks. If you are fitting to a petrol tank then Viton O-rings are recommended as ethanol content in modern fuels degrades nitrile over time. Viton O-rings available here →
The S3 can also be used as a position sensor by mounting the sender to a stationary part and clamping the float to a moving component. This is often used in industrial and agricultural machinery — a lifting trailer tailgate or a lifting keel on a yacht for example.
If you have an existing Wema sender, the identification plate on the head shows the product model, spec, length, Wema product code, output and batch code.
The code 001300 stamped on the head indicates an S3. How to identify a replacement Wema sender →
Specifications
- Fitting: 1¼" BSP parallel thread
- Material: 316 stainless steel
- Output: 0-190Ω / 240-30Ω resistance (standard), or 0-5V / 0-10V / 4-20mA (custom)
- Lengths: 150–1600mm standard
- Working voltage: 12V or 24V (draws power from gauge)
- Max carrying current: 1.2A
- Max switching current: 0.5A, 10W
- IP rating: IP65
- Operating temp: -40°C to +85°C
- Torque: 9 ±1 Nm (steel flange) / 7 ±1 Nm (nylon flange)
How long should your sender be? → | How to measure a level sender → | Replacing a floating-arm sender? →
[Please note: the code 001300 refers to the S3 head]