LIGO AIR User Guide
LIGO Air Manual
This user manual provides detailed instructions for the proper installation of the LIGO AIR fuel level sensor. The guide is intended for technicians, engineers, system integrators and end-users who are responsible for installing and maintaining the sensor in a variety of fuel tanks and vehicles.
The LIGO AIR fuel level sensor is a precision device designed by SOJI Electronics to measure the level of fuel in tanks with high accuracy and reliability. Correct installation is critical to ensure optimal performance and long-term durability.
Please read this manual thoroughly before beginning the installation process. Following the steps and recommendations provided will help you avoid common issues and ensure safe, effective operation of the sensor.
General Introduction
LIGO-AIR Fuel Level Sensor is developed and manufactured by SOJI Electronics JSC. The device is designed to measure the level of liquid fuel and other non-conductive liquids in vehicle tanks and stationary fuel storage, applicable in different fields. Equipped with advanced Bluetooth Low Energy technology, LIGO AIR enables seamless, real-time data transmission without the need for complex wiring and easy for installation.
The wireless fuel level sensor helps minimize the risk of signal wire tampering. In addition, the heavy-duty metal structure helps increase protection against environmental factors such as dust, moisture, vibration and high temperature conditions.
Key Features
- High accuracy up to 99.5%
- Directional antenna technology — communication range up to 1.5 times greater than typical market-available sensors
- Ultra-low power consumption: 9 µA in working mode and 4 µA in storage mode
- Optionally cut off or prolonged up to 6000 mm
- Wide operating temperature: -40 °C to +85 °C
- TX power up to 19.5 dBm (LIGO AIR PRO)
- Battery capacity up to 3600 mAh (optional)
- Replaceable battery
- Built-in accelerometer (LIGO AIR PRO)
- Built-in 32 Mb EEPROM for data logs (minimum 90 days) and setting logs (max 500 logs)
- Built-in anti-mud oil filter and anti-vibration springs
- IP69K waterproof standard
- 8–10 years of battery life
General Applications
- Trucks, excavators, heavy construction machines
- Marine vessels and electric generators
- Off-highway machinery in high-temperature and vibration environments
- Industrial oil storage tanks or stationary storage tanks
Product Variants
The LIGO AIR series offers three specialized versions, each optimized to meet specific operational demands:
| Variant | Description | Use Cases |
|---|---|---|
| LIGO AIR LxS | Standard cost-effective version that fulfills essential monitoring needs while maintaining reliable performance | Trucks, excavators, cement mixer trucks, heavy construction machines |
| LIGO AIR LxT | Extended-battery version designed for applications that demand long operational life (8–12 years) and reliable performance in harsh environments | High-temperature applications, long maintenance intervals |
| LIGO AIR PRO | Long-range version designed for applications requiring extended transmission distances or operation in environments with significant obstacles | Marine vessels, electric generators, industrial oil storage tanks, stationary storage tanks |
Performance Comparison
| Parameter | Competitive products | LIGO AIR LxS (Standard) | LIGO AIR LxT (Extended battery) | LIGO AIR PRO LxS (Extended range) |
|---|---|---|---|---|
| Battery life | 0.4× Standard (2–4 years) | Standard (6–8 years) | 1.5× Standard (8–12 years) | Standard (6–8 years) |
| Transmission range | 0.6× Standard | Standard | Standard | 2× Standard |
Technical Specifications
| Parameter | LIGO AIR (LxS, LxT) | LIGO AIR PRO |
|---|---|---|
| Standard length (L), mm | 700, 1000, 1500 ... up to 6000 mm | |
| Measuring error, % | ± 0.5 % | |
| Bluetooth specs | Bluetooth 5.4, IEEE 802.15.4-2006, 2.4 GHz, -95 dBm sensitivity | |
| TX power max | 6 dBm | 19.5 dBm |
| Advertising Protocol | SOJI Protocol (default), Mielta Protocol, Escort Protocol — selectable in mobile app | |
| Power supply (built-in Li-SOCl₂ battery) | 3.6 V × 2600 mAh (LxS) 3.6 V × 2400 mAh (LxT) |
3.6 V × 3600 mAh |
| Current consumption (working mode), µA | 9 | 27 |
| Measurement interval (second) | From 5 to 10 | |
| Advertising message interval (second) | From 5 to 10 | From 10 to 15 |
| Waterproof standard (IP) | IP69K | |
| Operating temperature (°C) | -40 ... +85 | |
| Resolution (bit) | 12 | |
| Accelerometer | N/A | Built-in |
| Memory | Built-in 32 Mb EEPROM | |
| Average sampling period (s) | 5 to 60 | |
| Absolute error in temperature measurement (°C) | ±2 | |
| Average service life (expected) | 10 years | |
| Storage condition | 15 °C to 30 °C, RH < 60% | |
Sensor Structure and Dimensions
| Manufacturer Part Number | L (mm) |
|---|---|
| LIGO AIR – L7S, L7T, LIGO AIR PRO – L7S | 700 ± 3 |
| LIGO AIR – L10S, L10T, LIGO AIR PRO – L10S | 1000 ± 3 |
| LIGO AIR – L15S, L15T, LIGO AIR PRO – L15S | 1500 ± 3 |
Important Installation Notes
- Install the sensor in the direction of maximum signal transmission — the directional arrow on the sensor cover should point toward the receiving device.
- Minimum allowable length of the measuring probe is 150 mm.
- Make sure there is no metal plate covering the sensor head, as this may block Bluetooth signal.
- Ensure that the signal strength (RSSI) at the receiving device is not less than -80 dBm. For weak signal cases, use a LIGO AIR PRO or a LIGO AIR Adapter.
- Change the default password provided by the manufacturer to prevent unauthorized access.
- Detailed mobile application instructions are described in LIGO Air Configuration.
Products and Accessories
| No. | Description | Qty (pcs) |
|---|---|---|
| 1 | LIGO AIR Fuel Level Sensor — Standard lengths: 700, 1000, and 1500 mm (custom lengths on request) | 01 |
| 2 | Oil filter | 01 |
| 3 | Gasoline-resistant rubber gasket | 01 |
| 4 | Bottom-stop and springs | 01 |
| 5 | Self-drilling screw M4.8 × 32 mm | 05 |
| 6 | Rivet and screw M5 × 20 mm | 05 |
| 7 | Protective cap | 01 |
| 8 | User manual | 01 |
Preparation
Fuel Tank Preparation
- Empty the tank, clean and dry it if necessary. For gasoline fuel tanks, all fuel vapors must be removed from the tank to prevent fire or explosion during installation.
- Select the installation location with the following requirements:
- The sensor's installation location must be as close as possible to the tank's geometric center and at its deepest point
- Ensure that the sensor avoids contact with reinforcement ribs and other equipment inside the tank
Drilling Holes
Drill a central hole (Ø42 mm), then drill four additional Ø7 mm holes for mounting screws as shown:
Notes: The mounting hole diameter depends on the material and thickness of the tank:
| Tank wall thickness | Fastener type | Mounting hole diameter |
|---|---|---|
| ≤ 3 mm | M5 rivet nut | 4 × Ø7 mm |
| > 3 mm | M4.8 self-tapping screw | 4 × Ø7 mm |
Important: Mounting hole positions must ensure that the sensor is installed in the direction of maximum signal transmission (the directional arrow on the sensor cover should point toward the receiving device).
Sensor Preparation
Cutting the Sensor Tube
The length of the sensor tube should be calculated by the formula:
L = H − 25 mm
Where:
- L — final tube length after cutting
- H — height of the tank at the installation point
After cutting, remove any burrs and clean the tube using fuel.
Note: The minimum length of the tube after cutting must be at least 150 mm (15 cm).
Installing Bottom-Stop Springs and Filter
Install the bottom-stop and the oil filter in sequence, as shown:
Installing Sensor on the Fuel Tank
- Apply gasket sealant to the fuel tank, gasket and sensor flange (using fuel-resistant RTV silicone gasket maker).
- Insert the LIGO AIR fuel sensor into the tank and fasten it securely using the appropriate screws (self-tapping screws or rivet nuts depending on tank thickness).
Note: Install the sensor in the direction of maximum signal transmission. The directional arrow on the sensor cover should point toward the receiving device.
Clearance Requirement: Ensure a minimum clearance of 150 mm between the top of the sensor and any overhead metal surface.
After installation, proceed with calibration as described in LIGO Air Configuration.
Installing Protective Cap
The protective cap should be installed after the sensor installation and calibration processes are completed. This cap helps prevent unauthorized access and protects the sensor from environmental factors such as sunlight and physical impact.
In cases when sensor inspection is required, the protective cap must be removed. Follow the removal procedure as shown:
Note: Please ensure that no parts of the sensor are damaged while removing the protective cap.
Sensor Seal Cover Removal
In cases when sensor inspection is required, the protective cap must be removed using the correct procedure (see image above). Incorrect removal may damage the sensor housing.
Solutions for Long-Range or Metal-Obstructed Environments
In some cases, when the distance between the sensor and the receiver is long, or when there are many metal obstacles causing signal attenuation, customers can:
- Choose the LIGO AIR PRO model — increased transmission power
- Install a LIGO AIR Adapter at the receiver side — boost the received signal
| Device combination | Bluetooth signal range |
|---|---|
| LIGO AIR + Telematics (tracker) device | Standard distance |
| LIGO AIR + LIGO AIR Adapter | 2 × Standard distance |
| LIGO AIR PRO + LIGO AIR Adapter | 4 × Standard distance |
Warranty
- The warranty period is 3 years from the date of shipment by the manufacturer.
- The warranty period and service life do not apply to the battery.
- Compliance with the specified operating, transport, and storage conditions is a prerequisite for the manufacturer's guarantee.
- The manufacturer reserves the right to modify the design and composition of the product without prior notice to the customer.
Revision History
| Date | Document | Version | Description |
|---|---|---|---|
| 18/06/2025 | Datasheet | 1.0 | Initial Release |
| 14/07/2025 | Datasheet | 1.0.3 | Minor changes |
| 14/10/2025 | Datasheet | 1.1 | Adding product variants |
| 18/06/2025 | User Guide | 1.0 | Initial Release |
| 14/07/2025 | User Guide | 1.0.4 | Minor changes |
| 14/10/2025 | User Guide | 1.1 | Minor changes |
| 04/11/2025 | User Guide | 1.2 | Update sensor structure drawing |