FINE LEAK SEAL TESTING: HERE’S HOW IT WORKS

Fine Leak Testing is accomplished by a two-part process:

Part 1: Fine Leak Preconditioning

Preconditioning with an InterTest Model 1014-C4 Fine/Gross Pressurization System — This unit performs the following process:

1. Devices are placed in one of the preconditioning chambers.
2. A vacuum is pulled on the chamber.
3. The chamber is pressurized up to 90 PSIA with helium.
4. Pressure is maintained for the prescribed time. (Usually 2 hours)
5. The pressure is automatically vented.
6. The devices are ready to be Helium Leak Tested in a Helium Leak Detector.

Part 2: Fine Leak Testing

Helium Fine Leak Testing is accomplished with a Helium Mass Spectrometer (manufactured by Agilent). Failed devices are determined by the following procedure:

1. Devices are placed in the test chamber/flapper box (after preconditioning).
2. The test button initiates the actual test.
3. If helium is detected which exceeds the preset leak rate set point, an alarm alerts the operator of a fine leak failure.

GROSS LEAK SEAL TESTING: HERE’S HOW IT WORKS

Gross Leak Testing is accomplished by a two-part process:

Part 1: Gross Leak Preconditioning

Preconditioning with the same InterTest Model 1014-CII Fine/Gross Pressurization System – This machine performs the following process:

1. Devices are placed in one of the preconditioning chambers.
2. A vacuum is pulled on the chamber to 5.0 mmHg.
3. Vacuum is maintained for the prescribed time (Usually 60 Minutes).
4. Fluorocarbon fluid (Type 1) is pumped into the chamber to ensure the immersion of all devices.
5. The chamber is pressurized up to 90 PSIA with nitrogen.
6. Pressure is maintained for the prescribed time. (Usually 2 hours)
7. The pressure is automatically vented, and the fluid is drained.
8. The devices are now ready to be Gross Leak Tested in an InterTest Bubble Detection System.

Part 2: Gross Leak Testing

Gross Leak Detection is accomplished with an InterTest Model 1014-CBL Bubble Detection System. Failed parts are determined by the following procedure:

1. Parts are placed on a dipping basket, then submerged in the observation tank of the InterTest Bubble Detection System. The tank contains a heated bath of fluorocarbon fluid (Type 2) at 125°C. The fluid is brightly illuminated and magnified, which improves the operator’s visibility.
2. The operator views the parts for a period of 30-60 seconds.
3. A device that fails this Gross leak test is detected by its emission of two large bubbles or a steady stream of bubbles from a single point on the package.

Gross Leak Test Theory:

In Part 1, Type 1 indicator fluid is forced into the “bad” package using the InterTest Gross/Fine Pressurization System. Type 1 fluid boils at approximately 80° C and has a density of 14.3 lbs./gallon. In Part 2, Type 2 indicator fluid is heated to 125° C in the InterTest Bubble Detection System. Type 2 fluid boils at approximately 200° C and has a density of 15 lbs./gallon. When a device containing Type 1 fluid is placed in the Type 2 fluid at 125°C, the Type 1 fluid boils, expands and forces its way out of the device at the point where it entered, i.e. at the bad seal or leak. It is visibly detected by a stream of bubbles that rise from the leak point of the device to the top of the Type 2 bath in the Bubble Detection System.

Recommended Equipment for Fine and Gross Leak Testing:

MIL-STD-883, 750, 202 & OTHERS

For additional technical assistance, or for product information, contact the InterTest Equipment Services factory.

Phone:  (408) 298-7747
Email: