SN61.XXAGHKNAX/VEGA: A Batching Tank That Prevents Ultrasonic Level Meter Malfunction

I. Design Objectives

• Core Requirement: Solve the problems of ultrasonic level meters being susceptible to interference and inaccurate measurement under complex working conditions through structural optimization and protective design.
• Applicable Scenarios: Batching processes with high requirements for level monitoring accuracy, such as food processing and chemical production.

II. Key Design Modules

1. Anti-Interference Structural Design

• Inclined Tank Body
  • Design Principle: The side wall of the tank forms a 5°-10° angle with the horizontal plane to reduce the interference of liquid fluctuations on ultrasonic signals.
  • Implementation: The tank bottom adopts a conical structure, combined with a guide pipe to control the liquid level drop and avoid air entrainment that forms foam.
• Waveguide Pipe Installation
  • Function: A vertical waveguide pipe (diameter ≥ 50mm) is installed under the probe to guide the vertical emission of ultrasonic waves and reduce signal attenuation.
  • Material Selection: 316L stainless steel or PVDF (polyvinylidene fluoride), which is corrosion-resistant and has strong signal penetration.
• Flange-Type Installation
  • Specification: The probe is vertically fixed on the tank top through a flange, with a perpendicularity deviation from the liquid surface ≤ 1° and a distance from the tank wall ≥ 30cm.
  • Blind Zone Control: A blind zone of ≥ 50cm is reserved according to the measuring range to prevent the probe from being submerged by liquid.

2. Anti-Foam and Defoaming System

• Constant Temperature Control Layer
  • Structure: The tank body adopts a double-jacket design with built-in electric heating films and temperature sensors to maintain stable liquid temperature (±1℃).
  • Principle: Temperature fluctuations ≤ 2℃ can reduce the migration of surface-active substances and foam generation.
• Defoaming Device
  • Mechanical Defoaming: A rotating blade-type defoamer is installed on the tank top, with a rotation speed of 50-100rpm, to break up foam on the liquid surface.
  • Chemical Defoaming: A defoamer injection port is reserved to support automatic dripping (e.g., silicone-based defoamers, dosage 0.1-0.5ppm).
• Flow Rate Optimization
  • Feed Pipe Design: A tangential feed port is adopted to reduce liquid impact; the pipe diameter is DN25-DN50, and the flow rate is ≤ 1.5m/s.
  • Liquid Level Control: The flow rate is adjusted by a variable frequency pump to avoid severe fluctuations in the liquid level.

3. Protection and Calibration System

• Protection Design
  • Protective Cover: IP68 waterproof and dustproof cover with built-in desiccant to prevent moisture intrusion.
  • Electromagnetic Shielding: The outer surface of the tank is sprayed with a conductive coating to reduce electromagnetic interference (e.g., from frequency converters, motors, etc.).
• Automatic Calibration Function
  • Temperature Compensation: A built-in temperature sensor to real-time correct the sound speed (sound speed = 331.5 + 0.6 × temperature).
  • Zero Calibration: Standard liquid (such as water) is automatically injected to calibrate the range before daily production, and an alarm is triggered if the error exceeds 5%.
• Fault Early Warning System
  • Monitoring Parameters: Signal strength, echo quality, temperature, current output.
  • Early Warning Mechanism: Switch to a backup level meter when data is abnormal, and prompt maintenance through the HMI interface.

III. Material and Installation Specifications

• Material Selection
  • General Scenarios: The tank body is made of 304 stainless steel, and the sealing ring is made of silicone.
  • Chemical-Grade Scenarios: The tank body is lined with PTFE (polytetrafluoroethylene), and the probe material is PVDF.
• Installation Specifications
  • Vertical Calibration: Use a laser level to ensure the probe is perpendicular to the liquid surface.
  • Grounding Requirements: The grounding resistance of the tank body ≤ 4Ω to prevent electrostatic interference.
  • Line Protection: Signal lines use shielded twisted pairs, laid in separate pipes, and avoid being parallel to power lines.

IV. Implementation Effects

• Measurement Accuracy: Liquid level error ≤ ±5mm; stable operation even when foam coverage exceeds 40%.
• Failure Rate: The anti-interference design reduces the malfunction rate of the level meter by more than 80%.
• Maintenance Cycle: The defoaming device is cleaned every 3 months, and the level meter is calibrated every 6 months.

V. Application Cases

• A syrup batching tank in a food factory: After adopting the inclined tank body + waveguide pipe design, the measurement error caused by liquid level fluctuations was reduced from ±20mm to ±3mm.
• An acid liquid batching tank in a chemical plant: With PVDF probes and constant temperature control, it operated continuously for 12 months in a highly corrosive environment.