Daily use and maintenance methods for American CTS leak detectors.
I. Daily Use
1. Carefully read and understand the principles, operating procedures, and button functions of the air tightness leak tester.
2. Before each test, first test the master part, compare whether the data is consistent with previous readings, and record the test data.
3. During testing, do not touch the test system with your hands, and do not hold the test product in your hands for an extended period while waiting for the test.
4. When encountering a product that requires retesting due to doubts, first place it back in its original position to be tested, and retest it only after testing several other products. Do not retest it immediately.
5. If you suspect a system abnormality (such as an excessive number of rejects), first test with a standard part to check whether the system is functioning properly.
6. Regular training and experience summarization, resource sharing
II. Maintenance and Care
1. Regularly check whether the system is functioning properly. Use a standard leak to test, compare the data against the recorded values, open the leak orifice for a normal test to see whether the reading is close to the leak rate value, and check the instrument's alarm status.
2. Use a multimeter to confirm whether the instrument is reliably grounded, and whether your ground wire is reliable.
3. Please ensure the compressed air is stable, dry, clean, oil-free and free of impurities.
4. Periodically recalibrate the leak orifice (certificate valid for one year), and check whether the instrument's leak orifice set value matches the value on the leak orifice label.
III. Common Issues and Solutions
1. Negative values appear during testing.
The main internal causes of negative values are a decrease in system volume or an increase in temperature.
(1) Check whether the test fixture moves during system testing.
(2) Whether the same workpiece is tested continuously
(3) Is the test time too long?
(4) At the previous station, whether the workpiece was heated
(5) Sensor failure
(6) Incorrect calibration parameters
(7) During testing, check whether hands are placed on the fixture.
(8) The workpiece held by the worker is too long, causing the workpiece to be raised.
2. The system has a leak.
1. Plug the instrument's self-test plug. If leakage still occurs,
a. Check whether the O-ring of the self-test plug is damaged.
b. Inspect the valve plate and connectors
c. Test the isolation valve
d. Check the leak orifice valve
e. Check the sensor
(2) Plug the instrument's self-test plug. If there is no leakage, check the system section by section for leaks.
3. Calibration failed
(1) Whether the interval time is sufficient
(2) Check whether the leak hole valve is open.
(3) Check whether the leak hole is clogged.
(4) Check the settings for the maximum and minimum allowable calibration values.
(5) Whether the test time is too long, with pressure decay exceeding 10% of the test pressure
4.What parameters is the calibration rate related to?
⑴ Pressure decay value when the system does not open the leak hole
(2) Size of the judgment criteria
(3) Time of the test phase
(4) Total test cycle time
(5) Size of the system volume
(6) The material of the workpiece, and whether it will deform during the testing process.
5. Poor repeatability
(1) Whether the interval time is sufficient
(2) Whether the state of the workpiece is consistent each time
(3) Is the test cycle time too short?
(4) Is the sealing state of the fixture consistent each time?
6. Regarding the issue of checking for bubbles in water
If the acceptance criterion is 1.0 sccm, then for the instrument, any measured value below this threshold is a pass, and anything above is a fail. However, this does not mean that no bubbles will appear during water immersion. If the bubble is 4 mm in diameter, at this rate, theoretical calculation shows approximately 29 bubbles per minute.
7. System instability
⑴ Do not use the internal power supply for the instrument's IO power; otherwise, external interference may be introduced into the system.
(2) Whether the enclosure is live
IV. A Useful Formula
Impact of system volume on testing: The smaller the system volume, the higher the correction rate and the better the test results.
For example:
dP × V
L.R. = ----------------------
Patm
As can be seen from the formula, the leak rate (L.R.) remains unchanged. If the system volume (V) is reduced by 50%, the pressure decay (dP) corresponding to this leak rate doubles, and the detection sensitivity doubles accordingly. That is, if 1 sccm causes a pressure loss of 100 Pa, then for every 1 Pa change in the system, the leak rate sensitivity is 0.01 sccm; if 1 sccm causes a pressure loss of 1000 Pa, then for every 1 Pa change in the system, the leak rate sensitivity is 0.001 sccm. The benefits are obvious.
American CTS air tightness leak detector
