The selection of a hydraulic tank level gauge requires comprehensive consideration of measurement requirements, working environment, medium characteristics, and system compatibility.

Below are detailed steps and considerations:

1. Determine the Measurement Principle  

Choose the type of level gauge based on the application scenario. Common types include:  

- Magnetic Level Gauge: Resistant to high pressure and temperature, provides visual level indication, suitable for transparent or semi-transparent tanks.  

- Float-Type Level Gauge: Simple structure, low cost, but lower accuracy; ideal for general industrial applications.  

- Ultrasonic Level Gauge: Non-contact measurement, suitable for sealed tanks or corrosive media, but affected by foam or vapor.  

- Capacitive Level Gauge: Works with high-temperature, high-pressure, or viscous media; requires calibration based on dielectric constant.  

- Differential Pressure Level Gauge: Calculates level via pressure difference, suitable for sealed systems but needs regular maintenance.  

2. Installation Method and Structural Compatibility  

- Mounting Position: Top-mounted, side-mounted, or flange-connected; must match tank port dimensions.  

- Material Selection: Choose stainless steel, PTFE, etc., based on hydraulic oil properties (e.g., corrosiveness, temperature).  

- Vibration Resistance: Select anti-vibration models for tanks in vibrating environments (e.g., construction machinery).  

3. Range and Accuracy Requirements  

- Measurement Range: Cover the minimum (MIN) to maximum (MAX) tank level, typically with 10%~20% margin.  

- Accuracy Class: ±1%~2% for general applications; ±0.5% or higher for precision systems (e.g., servo hydraulics).  

4. Medium and Environmental Adaptability  

- Hydraulic Oil Properties: Viscosity, density, temperature range (e.g., -40°C~120°C), presence of particles or additives.  

- Environmental Conditions:  

  - Temperature: High-temperature environments require heat-resistant materials (e.g., 316L stainless steel).  

  - Pressure: High-pressure tanks (>10MPa) need pressure-resistant seals.  

  - Explosion Protection: Hazardous areas (e.g., mines, chemical plants) require ATEX/IECEx certifications.  

5. Signal Output and Interfaces  

- Output Types:  

  - Analog signals: 4~20mA, 0~10V (for PLC/DCS integration).  

  - Digital signals: RS485, HART, Modbus (for remote monitoring).  

- Display: Optional local scale or LED digital display.  

6. Safety and Certifications  

- Standards Compliance: ISO 4401 (hydraulic systems), DIN EN 837 (pressure instruments), etc.  

- Protection Rating: IP65/IP67 (dust/waterproof) for outdoor or humid environments.  

- Explosion-Proof Certification: Ex d/IIC T6 (for explosive gas environments).  

7. Maintenance and Lifespan  

- Ease of Maintenance: Magnetic gauges require no power and have low upkeep; capacitive types need periodic calibration.  

- Lifespan: Industrial-grade gauges typically last >5 years; consider seal aging resistance.  

Selection Flowchart  

1. Define level range and accuracy → 2. Analyze medium properties (viscosity, temperature) → 3. Determine environmental conditions (pressure, explosion-proof) → 4. Select mounting method and output → 5. Compare brands and budget → 6. Validate compatibility and lifespan.  

Application examples

- Construction Machinery Hydraulic Tank: Magnetic level gauge (vibration-resistant, high-pressure tolerance, 4~20mA output).  

- Marine Hydraulic System: Capacitive level gauge (corrosion-resistant, IP67 rating, suitable for unstable environments).  

By following these steps, you can systematically select a level gauge that ensures efficient integration with the hydraulic system.