Package Altitude Simulation Testing: Equipment and Procedure

By Tanner Vandenberg, CEO, FlexPak Leak Detectors Inc.

A package altitude simulation test puts a sealed package under the low pressure of a cargo hold to see whether it survives the trip. It is a conditioning test, not a leak test, and that distinction decides whether your results mean anything.

What is altitude simulation testing?

Altitude simulation testing lowers the air pressure around a sealed package to match a given altitude, holds it there, and then checks the package for damage or deformation. It reproduces what happens in an unpressurised cargo hold or a truck crossing a mountain pass, where the air outside the package thins and the gas inside pushes outward.

ASTM D6653/D6653M-13 is the standard method, written by committee D10.21, Packaging and Distribution. The result is qualitative: the package either survives the hold or it does not.

Why a package that passes at sea level fails in the air

At sea level the pressure inside and outside your package is roughly equal. Take that package to 16,000 feet and the outside pressure drops to about 54.9 kPa while the inside stays where it was. The seal now has to hold a pressure differential it never saw on your line.

Feeder aircraft, the smaller planes that move freight between regional hubs, can reach around 19,000 feet. That is the trip that finds the weak seal, and it happens after your QA sign-off. High altitude is the condition altitude packaging has to survive, and it is the one your line never simulates.

The ASTM D6653 procedure

The numbers matter, because a test run at the wrong rate or the wrong temperature is not the test.

1. Condition the package. 5.6 +/- 2 C (42 +/- 3.6 F) for at least 24 hours. If cold conditioning is not available, use standard 23 +/- 2 C.
2. Raise the vacuum slowly. About 305 m (1,000 feet) every 30 to 60 seconds. Rushing it is the most common way to get a result you cannot defend.
3. Reach the target pressure. The equivalent of 4,877 m (16,000 feet) +/- 5% for cold-conditioned packages, or 4,267 m (14,000 feet) if you conditioned at standard temperature.
4. Hold for 60 minutes.
5. Release at the same rate you climbed.
6. Examine the package for damage, deformation, or seal failure.

For reference, 8,000 feet is about 75.3 kPa and 16,000 feet is about 54.9 kPa. A vacuum gage reading 0 to 100 kPa (0 to 30 in. Hg) covers the whole range.

What altitude simulation testing does not do

D6653 conditions a package. It does not detect leaks. That sounds like a technicality until you realise what it means in practice: a package can come out of a D6653 hold looking perfect and still have a leak too small to deform it.

So altitude conditioning is paired with a detection method, not used instead of one. Run bubble emission under ASTM D3078 after the altitude hold and you get both answers: did the package survive the pressure differential, and is it actually sealed.

One more honest limit. FPFA-T specifications list ASTM D4169, and FlexPak covers the altitude portion of D4169 through D6653. It does not cover the full distribution suite, so no drop, vibration, or compression testing. If an auditor has handed you full D4169, altitude is one part of what you need.

For the standard itself and where it sits among the shipping standards, see the high-altitude shipping guide.

Equipment for altitude simulation testing

You need three things: a chamber that seals, a vacuum source that can pull and hold a controlled level, and a gage you can read and record.

A FlexPak Leak Detector chamber pulls to roughly 0 to 27 in. Hg (0 to 90 kPa), which covers the D6653 range with headroom. The chamber is the same one used for bubble emission, so the altitude hold and the leak test happen in one piece of equipment rather than two.

For low-pressure packaging bags and other flexible formats, the thing to watch is not whether the chamber reaches the pressure. It is whether you can hold it steady for a full hour without drift.

Manual, semi-automatic, or fully automatic

This is the decision most buyers actually face, and it comes down to how many times you will run the test.

• Manual. You control the vacuum and time the hold yourself. Fine for occasional testing. The risk is operator-to-operator variation on the climb rate.
• Semi-automatic (FPSA-T). Two setpoints. Repeatable levels without the full controller.
• Fully automatic (FPFA-T). 24 setpoints and 24 altitude tests, with data logging. This is the one that matters if you are testing against an audit, because the logged run is the evidence.

If you are running altitude conditioning once a quarter, manual is honest. If you are running it weekly and someone will ask for records, the controller pays for itself in the paperwork alone.

Frequently asked questions

Does altitude simulation testing detect leaks?

No. It conditions the package under low pressure and you inspect for damage afterward. Pair it with a detection method such as ASTM D3078 bubble emission to find actual leaks.

What altitude does ASTM D6653 test to?

16,000 feet +/- 5% for cold-conditioned packages, or 14,000 feet at standard temperature, held for 60 minutes.

How long does the test take?

The hold alone is 60 minutes, plus the climb and descent at 1,000 feet per 30 to 60 seconds, plus at least 24 hours of conditioning beforehand.

Can I use the same chamber for altitude testing and leak testing?

Yes. A FlexPak chamber does both, which is why most customers run the altitude hold and the bubble test on one unit.

Is altitude simulation testing the same as ASTM D4169?

No. D6653 covers the altitude portion. D4169 is a full distribution suite that also includes drop, vibration and compression, which FlexPak does not perform.

About the author

Tanner Vandenberg is CEO of FlexPak Leak Detectors Inc., which builds the equipment described here at its St. Catharines, Ontario facility. Connect with Tanner on LinkedIn.