To calculate leakage in a vacuum system, you need to perform several measurements and apply a specific formula. Below is the basic procedure:

Steps to Calculate Leakage

1. System Preparation:

  • Ensure the vacuum system (vacuum furnace, vacuum coating machine) is fully installed with no major gaps.
  • Activate the vacuum pump to create maximum vacuum conditions.

2. Measure Initial Pressure (P1):

  • Use a vacuum gauge (or system’s built-in gauge) to determine the initial pressure (P1).
  • Record the initial pressure value.

3. Determine Sampling Time (t):

  • Close the isolation valve between the vacuum pump and the vacuum chamber.
  • The time interval (t) is measured from the moment the valve is closed until the next pressure reading (P2).
    ⏱️ Recommended minimum: 1 hour. The longer the time, the more accurate the leak rate.

4. Measure Pressure (P2):

  • After time t, use the vacuum gauge to determine the pressure in the system (P2).
  • Record this pressure value.

5. Calculate Leak Rate (L): Use the following formula:

HOW TO CALCULATE LEAKAGE IN VACUUM SYSTEMS CONG-THUC-TINH-DO-RO-RI-TRONG-MOT-HE-THONG-CHAN-KHONG-3

Where:

  • L = Leak rate (Pa·m³/s or mbar·l/s)
  • V = Volume of the system (m³)
  • P1 = Initial pressure (Pa)
  • P2 = Pressure after time t (Pa)
  • t = Measurement time (s)
⚠️ Notes:
  • Ensure high measurement accuracy by calibrating pressure gauges and volume precisely.
  • If the leak rate is high, inspect all connections and components to identify and fix leak points.

I. Choosing the Right Leak Detection Method

Based on the calculated leak rate, select a suitable detection method:

🔹 Large Leaks

  • Symptoms: Fast pressure drop, large gas leakage
  • Recommended Method: Soap Bubble Test
    → Simple and effective for detecting large leaks
 
HOW TO CALCULATE LEAKAGE IN VACUUM SYSTEMS CONG-THUC-TINH-DO-RO-RI-TRONG-MOT-HE-THONG-CHAN-KHONG-1

🔹 Medium & Small Leaks

  • Symptoms: Slow pressure drop, minor gas leakage
  • Recommended Method: Helium Leak Detector (ULVAC)
    → Detects leak rates as low as 5×10⁻¹³ Pa·m³/s, ideal for hard-to-reach areas
HOW TO CALCULATE LEAKAGE IN VACUUM SYSTEMS CONG-THUC-TINH-DO-RO-RI-TRONG-MOT-HE-THONG-CHAN-KHONG-2
HOW TO CALCULATE LEAKAGE IN VACUUM SYSTEMS CONG-THUC-TINH-DO-RO-RI-TRONG-MOT-HE-THONG-CHAN-KHONG

Image: Engineer inspecting vacuum system leakage using ULVAC helium leak detector.

II. Tips for Choosing Detection Method

  • Accuracy: Choose methods with high precision to pinpoint leak locations
  • Sensitivity: Use helium-based methods for detecting micro-leaks
  • Safety & Convenience: Ensure the method is safe and practical for technicians
📞 If you have any questions or issues regarding vacuum leakage, feel free to contact ULVAC. We’re always ready to assist! Hotline:
  • Mr. Ngọc: 0988 248 567
  • Ms. Hảo: 0936 151 138
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