How to calibrate the volume size of an air leak tester - standard leak calibration

Q: The air tightness product shows no abnormality, but the air tightness test shows an abnormality?

During testing, when an abnormality is found, it is either a problem with the instrument or a problem with the product sealing. The process of elimination can be used. Seal off the instrument port and test whether there is a leak inside the instrument. If the instrument is fine, then the problem is confirmed to be on the product side, and at this point, the foam spray method can be used for troubleshooting.

Q: How is the volume calibrated on an air tightness tester?

There are many brands of leak detectors on the market. For volume calibration, different manufacturers use different methods, but all are calculated based on the formula for air tightness testing. As long as you understand the calculation method, you can roughly calculate the volume. Calculation formula: LR sccm=60(V×∆p）/（Patm×t） 

To calculate the volume, first confirm that you know: 1. LR sccm (the leak rate value of the leak hole); 2. t, the test time of the product.

Step 1: First test the product with the instrument, test for 10s, pressure decay ∆p=2pa 
Step 2: Under the same conditions, insert a leak hole (LR=2sccm)   pressure decay ∆p=100pa

Then the volume can be roughly calculated: 2 sccm = 60 (V x (100 Pa - 2 Pa) / (100000 Pa x 10 s))

Substitute into the formula and the volume is calculated.

Q: What is the calibration method for the standard leak orifice of an air tightness tester?

Answer the four major functions of the standard leak orifice in air tightness tester calibration tools:

I. Standard leak orifices can verify the sensitivity of an air tightness tester;

2. Standard leaks can be used to confirm leak rate accuracy;

3. Standard leaks can be used to measure the pumping speed of a vacuum pump;

4. It can also be used to calibrate vacuum gauges and perform other functions.

For example, when the product test standard is based on sccm leak rate, a calibrated leak orifice can be inserted during testing to compare the leak orifice data with the test data.

Q: What is the calculation formula for high-voltage wiring harness air tightness?

Answer: LR sccm = 60 (V × ∆p) / (Patm × t)

( Note: LR indicates leak rate; LRsccm indicates the gas leak rate at standard atmospheric pressure and 25°C.)

Patm is atmospheric pressure, and t is the test time (not the fill or stabilization time).

V is the volume (internal volume of the instrument + internal cavity volume of the product pipeline)

∆p is the differential pressure value