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Radar Tank Level Sender
Simarine Radar Tank Sender (150–2000 mm): high-precision radar with automatic calibration for accurate, non-contact liquid level measurement in plastic tanks. Choose the analog STR1 for versatile outputs (0–190 Ω / 240–30 Ω resistance, 0–5 V voltage), or the digital STR2 for seamless NMEA 2000 integration, with Bluetooth via the Simarine App. One sensor for every system.
Patent Pending –EP26171650.0
Smart, Accurate Tank Level Measurement
Measure your liquid tank level
A) Benefits & Choosing
What will I gain by choosing this sensor?
• Precise, stable readings with no moving parts and no holes below the liquid line; a low-profile body (≈32 mm high) for tight spaces.
• Top-mount radar measures through plastic tank lids—and on metal tanks via a proper opening/adapter—reducing installation risk and ongoing maintenance.
What are the pros and cons vs. standard senders?
• Pros: non-contact, no fouling/corrosion, app-based setup, millimeter-level accuracy, long life.
• Cons: must mount on top; through-lid works only with plastic (for metal tanks use an opening/adapter); price is higher than basic float senders but far lower than other external radar options.
How will it simplify installation?
• Top-mount, no tank penetration: nothing inside the tank; no side/bottom drilling.
• Peel-and-stick mounting: clean/dry the surface, then remove the liner and bond the sender directly to a plastic lid; for metal tanks, bond it to the approved adapter.
• Clear line-of-sight: through-lid on plastic; for metal, the adapter provides the opening so the radar looks straight down.
• App commissioning: quick Bluetooth setup and calibration in the Simarine app.
Which model should I pick (STR1 vs STR2)?
• STR1: analog inputs (0–190 Ω / 240–30 Ω / 0–5 V).
• STR2: NMEA 2000 (PGN 127505).
• If you only need local wireless app setup/monitoring (no network integration), pick STR1 as the more cost‑effective option.
B) Compatibility & Outputs
What can I connect it to?
• STR1: analog gauges/controllers using 0–190 Ω, 240–30 Ω, or 0–5 V — all three outputs are available simultaneously.
• STR2: NMEA 2000 displays/MFDs.
Do I need a Simarine display (PICO/VIA/Nereide)?
• No. STR1 can feed third‑party analog inputs.
• STR2 publishes to the NMEA 2000 bus.
Can I connect it to other devices to display data?
• STR1: use the analog standard your device expects (0–190 Ω / 240–30 Ω / 0–5 V).
• STR2: works with MFDs that receive PGN 127505 (Fluid Level)—e.g., Simrad/Lowrance/B&G (NSX/Zeus/NSS families) and Raymarine Axiom. Note: many Garmin models show 127505 for Fuel only; check your model’s PGN support for other fluids.
Are all STR1 analog outputs available at once?
Yes—0–190 Ω, 240–30 Ω, and 0–5 V can be used simultaneously.
Will STR1 work with legacy 240–33 Ω gauges?
Yes—use the 240–30 Ω mode.
Which NMEA 2000 messages does STR2 send?
PGN 127505 (Fluid Level); typical network update about 0.5 Hz.
C) Electrical & Ratings
What supply voltage and current are required?
8–35 VDC operating; typical current ~14–20 mA @ 12 V.
Do I need to fuse the supply?
Yes—follow system standards; place a suitable inline fuse near the power source.
Cable length and wire gauge guidance?
Longer cable on resistive outputs (0–190 Ω, 240–30 Ω) can cause errors due to cable resistance. (Applies to those two outputs.)
D) Tank Materials & Fitment
What material can the tank be made of?
Through-lid measurement works on plastic or fiberglass (GRP) tank tops that are flat and rigid. For metal tanks, bond the metal-tank adapter; do not bond directly to metal. The adapter should provide a non-metallic window and a flat mounting surface so the radar has a clear, vertical line-of-sight into the tank.
Supported tank height?
150–2000 mm total tank height.
How do I mount this sensor to the tank?
- Top-mount only. Sensor faces straight down; bottom surface parallel to the liquid at rest.
- Surface prep: flat, rigid, clean, dry area.
- Peel-and-stick: remove liner, place flat, press firmly and hold (exact press/cure time Needs confirmation).
- Metal tanks: bond to the Simarine metal-tank adapter, not directly to metal.
- Cable strain relief: secure the cable so it cannot pull/twist the sensor or peel the tape.
Can I mount on a sloped or curved lid?
The beam must be vertical. Use a wedge/spacer or adapter to correct angle; wedges/adapters may affect measurement.
Where should I avoid placing it?
Avoid above baffle walls or near strong inlets/return jets or complex features that could reflect the beam. Keep at least a few cm from the edge; ideally install near the tank center.
E) Commissioning & Calibration (BLE app)
Does the sender need an initial set‑up?
Yes. A one-time initialization is required in the app, where the tank name, tank volume, units (e.g., liters), and sensor calibration are defined.
The tank height can either be entered manually or obtained automatically by the sensor, if the tank is empty (automatic empty-tank calibration).
Important: do not perform initial sensor calibration before mounting the sensor on the tank. Until initial calibration is completed, the LED blinks red; after successful calibration, it blinks green.
How is tank calibration performed?
In the Simarine app (BLE): select the tank → Settings → Tank Calibration.
For each calibration point: enter the actual volume and tap Use Current Sensor Value to capture distance (or type it manually).
Save and repeat—up to 100 points. You can edit or delete points later. (Tank calibration defines the volume‑vs‑height curve; it is separate from Initial setup in Q19.)
What information is required to enter a calibration point?
Enter the actual volume (liters). Tap Use Current Sensor Value to capture distance, or type it manually.
Can irregular-shaped tanks be calibrated?
Yes—up to 100 points (volume + captured sensor distance).
Can I edit calibration later?
Yes—add/adjust points any time; a how‑to video is in preparation.
Can the initial set‑up be started with the tank empty?
Yes, but only if the tank height is entered manually. When using automatic tank height estimation, the bottom must be covered with liquid (≈1–2 cm is sufficient).
Fastest way to capture points during filling?
Pause at known increments (e.g., every 10–20%), enter the volume, then tap Use Current Sensor Value.
Can I import/export or clone calibration curves?
Yes—calibration points can be exported via the app.
F) Performance & Behavior
What’s the typical resolution and update rate?
Approx. 7 mm resolution with a typical 1 Hz update (STR1) and 0.5 Hz (STR2).
Is there a dead zone near the lid?
It measures to the top, but for liquid distances < ~40 mm from the radar, the output may not reflect actual level.
How stable are readings with slosh?
Slosh filtering is applied inside the sensor, ensuring stable and reliable output.
Does foam affect readings?
Foam can weaken or scatter radar echoes; impact depends on thickness/consistency and placement. Developer note: in grey/black water tanks foam typically binds to dirt and collapses, so it’s usually not a problem in real use.
Condensation on the tank top?
Light condensation generally isn’t a problem, but standing water or thick films on the lid can disturb the radar path. Keep the mounting area clean/dry; add drip/strain relief if condensation is persistent.
G) STR2 / NMEA 2000 specifics
Which NMEA 2000 PGNs and rates are used?
PGN 127505 (Fluid Level); level updates around 0.5 Hz.
How are tank instance, fluid type, and capacity set?
All NMEA 2000–related configuration is modified in the app. The option appears automatically when connected to an STR2 device.
Is STR2 certified for NMEA 2000?
It is currently in the certification phase.
H) Wiring & Connections
Power & Outputs (confirmed elements only)
- Supply: 8–35 VDC (fuse per system standards).
- STR1 outputs: 0–190 Ω, 240–30 Ω, 0–5 V.
- Simultaneous outputs: all three analog outputs can be used at once on STR1.
- STR2: NMEA 2000 backbone connection.
Wire colors (from product label in photo)
- Red → +8–35 VDC
- Black → GND
- Blue → COM
- White → 0–190 Ω
- Yellow → 240–30 Ω
- Green → 0–5 VDC
- Pin/terminal order not specified—use official wiring sheet if required.
Is it only for plastic tanks?
Answered in D)
I) Troubleshooting
My gauge reads backwards or the wrong scale.
Ensure the selected output matches the gauge (0–190 Ω / 240–30 Ω / 0–5 V).
Re‑run calibration if you changed ranges. Some gauges need a power cycle.
The reading is unstable.
Power/ground: verify stable 8–35 V and solid grounding.
Mounting: ensure the sender is flat, firmly bonded, and no water is trapped between lid and sender; add strain relief so the cable can’t tug the unit.
Setup: if issues persist, repeat Initial setup and recheck Tank Calibration points.
No reading at all.
Verify 8–35 V supply and wiring to COM/ground.
Ensure the green LED blinks and the app detects the device.
Mapping — “Additional questions from users” → Where answered
How is the device secured to the tank?
Answered in A) and D).
I would love to know what type of output this has?
Answered in B) and H)
Is it only for plastic tanks?
Answered in D)
Will it work in RV water tanks with irregular shape? How does it calibrate?
Answered in E)
Will it work if the tank is stainless?
Answered in D) (use Simarine metal‑tank adapter).