The part number **47LLC-S2D2YR-R** refers to a high-performance **Liquid Level Sensor** manufactured by **SST Sensing Ltd**. These sensors are widely used for point-level detection of liquids in demanding industrial and commercial environments. --- ## 1. Technical Overview This sensor utilizes **Optical (Infrared)** technology. It functions by detecting the change in refractive index between air and liquid. | Feature | Specification | | :--- | :--- | | **Technology** | Optical / Infrared LED & Phototransistor | | **Output Type** | Digital (Push-Pull) | | **Supply Voltage** | 4.5V to 15.4V DC | | **Supply Current** | 2.5mA max | | **Operating Temperature** | -40°C to +125°C | | **Pressure Rating** | Up to 7 bar (101 psi) | | **Housing Material** | Polysulfone (Engineered Plastic) | --- ## 2. Part Number Breakdown The suffixing and coding explain the specific physical and electrical configuration: * **47LLC:** The Series identifier (High-performance Optomax Industrial line). * **S2:** Refers to the housing style (Standard 1/2" SAE thread). * **D2:** Indicates the electrical output configuration (usually Push-Pull, capable of sinking/sourcing current). * **YR:** Specifies the cable/connector type and output logic (Yellow/Red lead configuration). * **-R:** Generally indicates "RoHS Compliant" or "Bulk/Reel" packaging depending on the specific distributor. --- ## 3. How It Works 1. **Dry State:** An internal Infrared LED emits light into a plastic tip (prism). Because the tip is surrounded by air, the light reflects internally back to a phototransistor. 2. **Wet State:** When liquid covers the tip, the refractive index changes. The light escapes into the liquid, causing the phototransistor to receive less light, which triggers the output signal. --- ## 4. Key Advantages * **No Moving Parts:** Unlike mechanical float switches, there are no parts to jam or corrode. * **Compact Size:** Ideal for applications with limited space. * **High Precision:** Detects levels within ±1mm accuracy. * **Robustness:** The Polysulfone housing is resistant to most oils, fuels, and common chemicals. --- ## 5. Wiring Diagram (General) The device typically uses a 3-wire system: ```text Red Wire -> Vcc (4.5V - 15.4V) Green Wire -> Ground (0V) Blue Wire -> Output Signal (Digital High/Low) ```