ASTM D3078: The Bubble Emission Test Explained

Last updated: March 2026

A QA manager at a flexible packaging facility receives a new contract from a national retailer. The compliance line reads: ASTM D3078 required. She knows it’s a bubble test. She’s pretty sure she already has the right equipment. But when her team sits down to validate the protocol, questions pile up fast. What vacuum level do they use? Their newest SKU is vacuum-sealed. Does that even work with this test? What size leak will they actually catch? And if a marginal seal slips through, what’s their liability?

These aren’t edge cases. They’re the questions every QA team runs into when they encounter ASTM D3078 for the first time, or the fifth. This guide covers the method itself: how it works, what genuinely affects its sensitivity, which packages it applies to, and how it compares to the other standards you’ll encounter. No paywalls. No fluff. Just the method.

What Is ASTM D3078?

ASTM D3078 is a standardized test method for detecting gross leaks in flexible packages that contain headspace gas. The package is submerged in liquid inside a transparent vacuum chamber. As vacuum is drawn, headspace gas inside the package expands and escapes through any leak points, producing a visible, steady stream of bubbles at the failure location.

That’s the short version. Here’s what matters for your QA program: D3078 is a detection method, not a conditioning method. It identifies leaks that exist at the time of testing. It’s designed for gross leak detection, covering visible channel defects, seal failures, and punctures that allow gas to escape under vacuum. It is not a microleak test, and it does not quantify leak rate. For a broader look at how bubble emission testing fits into a QA program, see our bubble testing guide.

The standard is published and maintained by ASTM International. The current active version is ASTM D3078-02 (reapproved). If your contract or customer spec references “ASTM D3078,” this is the document they mean.

What is ASTM D3078? ASTM D3078 is the standard test method for detecting gross leaks in flexible packaging using bubble emission. The package is submerged in liquid and placed under vacuum. Escaping headspace gas produces a visible stream of bubbles at any leak point. It is a qualitative, visual pass/fail test. Small leaks may not be detected. It’s one of several seal integrity test methods used in flexible packaging QA.

How the D3078 Bubble Emission Test Works

The test is simpler to run than it is to describe on paper. Here’s exactly what happens, step by step.

1. Fill the test chamber with immersion fluid. Water is the most common choice. Water with a wetting agent (a surfactant that lowers surface tension) is generally more sensitive, particularly for smaller defects. Room-temperature fluid only. Hot water can crack an acrylic chamber.
   
2. Submerge the package. Place the package in the water bath and hold it down so it stays fully submerged throughout the test. A hold-down plate or fixture keeps it in position.
   
3. Draw vacuum slowly. The standard calls for a controlled vacuum draw rate of approximately 1 inch Hg per second. Drawing too fast can cause false positives from entrapped air or package distortion. Take your time here.
   
4. Hold at the target vacuum level for around 30 seconds. Vacuum is typically held for approximately 30 seconds, though the actual hold time is established during your process validation. During this hold, watch for a steady stream of bubbles, not isolated bubbles (which are normal from entrapped air on the package surface), but a continuous, repeating stream originating from a single location.
   
5. Identify the leak location. This is one of D3078’s biggest practical advantages: you see exactly where the leak is. A steady stream from a corner seal tells your operator something entirely different than one coming from the body of the film. That location is actionable and points directly to what needs adjusting on the line.
   
6. Check for fluid ingress. After the test, inspect the inside of the package for fluid entry. Internal fluid that wasn’t there before confirms a fail, even if no visible bubble stream was observed during the vacuum hold.
   
7. Release vacuum and remove the package. Vent the chamber slowly, remove the package, and log the result.
   

What Affects Sensitivity: Vacuum, Headspace, and Fluid

Here’s where most articles stop. Here’s where we don’t.

ASTM D3078 is a gross leak test, but actual sensitivity varies significantly based on variables your team controls. Per the interlaboratory precision data in ASTM D3078-02, Section 12, sensitivity is approximately 1 x 10⁻⁵ atm·cm³/s under controlled lab conditions. That’s a best-case figure. In practice, four things drive whether you find a leak or miss it.

Vacuum Level

The vacuum level you set is the single biggest driver of sensitivity. Here’s what the data shows, per the interlaboratory precision data in ASTM D3078-02, Section 12:

• At low vacuum (12.5 ± 0.5 in. Hg): very small leaks are essentially non-detectable.
• At medium vacuum (18.5 ± 0.5 in. Hg): very small leaks remain essentially non-detectable.
• At high vacuum (24.5 ± 0.5 in. Hg): very small leaks are detected in roughly 78% of trials, approaching this method’s detection limit.

The right takeaway isn’t “always go to 24.5 inHg.” It’s to match your vacuum setpoint to your actual shipping conditions. Vacuum levels are typically selected based on package strength, headspace volume, and product behavior, and are validated during process setup. Many North American manufacturers use 12 inHg as a starting benchmark. It covers the pressure differential most domestic air freight routes create. If your product ships on nonpressurized feeder aircraft or over high-altitude ground routes, a higher setpoint may be appropriate.

A common approach: identify the vacuum level at which your package seals fail (the burst point), then test at roughly 90% of that. If seals fail at 16 inHg, test at approximately 14 inHg.

One practical safeguard: once you’ve validated a vacuum setpoint for a given SKU, the FPFAT fully-automatic controller stores up to 24 validated bubble test recipes (recipes #1–24) so operators can run the right protocol every time without accessing calibration settings. Validated setpoints don’t drift across shifts.

Not sure which vacuum level fits your package? Our team can help you figure that out in a 15-minute call – book here.

Headspace Volume

D3078 requires headspace gas to function. No headspace means no meaningful pressure differential under vacuum, which means no bubble stream, even if a defect is present. This is physics, not a flaw in the method.

Dense or liquid-filled products that consume most of the interior volume create a more challenging test environment. Product can also physically plug small openings, suppressing bubble formation at a defect site even when one exists. Both factors mean sensitivity is always package-specific and must be validated for your exact SKU, not assumed from a general standard.

Packages with little or no headspace cannot be reliably evaluated without air introduction before testing. FlexPak’s VAC Attachment solves this by injecting a brief air shot into vacuum-sealed packages, creating enough internal pressure for D3078 to function correctly. Without it, vacuum-sealed packages may false-pass regardless of whether a defect is present. One important note: testing with the VAC Attachment is a destructive process. The package is punctured for air injection and cannot be resealed after testing. Factor this into your sampling plan.

Immersion Fluid

Lower surface tension fluids, such as water with a wetting agent versus plain water, are generally more sensitive. If your current program uses plain water and you want to improve detection at the margins, switching to a wetting agent solution is one of the more straightforward validations to run. FlexPak’s transparent acrylic chamber is compatible with all four ASTM-listed immersion fluids (water, water with wetting agent, denatured alcohol, and mineral oil) and provides clear observation through the chamber during the full vacuum hold.

What to Say and What Not to Say

The sensitivity of D3078 is frequently misrepresented in the field. Here’s the accurate framing:

• Accurate: “ASTM D3078 detects gross leaks in flexible packages by making escaping gas visible as a stream of bubbles under vacuum. Sensitivity depends on vacuum level, headspace volume, product type, and packaging material. Small leaks may not be detected.”
• Not accurate: “D3078 detects leaks down to 250 microns.”

That figure belongs to ASTM F2096, and even then it carries a published probability qualifier (approximately 81%, based on round-robin data). Applying a micron sensitivity claim to D3078 is technically incorrect and creates a compliance liability. The standard does not specify sensitivity in microns.

Which Packaging Types Does D3078 Apply To?

D3078 was developed for flexible packages, and in practice that covers a wide range of formats.

Formats where D3078 works well:

• Flexible pouches and bags (stand-up, flat, gusseted)
• Flow wrap and pillow pack formats
• Modified atmosphere packaging (MAP), provided the gas flush creates sufficient headspace
• Stick packs and sachets, testable in multiples using a dedicated fixture
• Blister packs with film lidding, depending on headspace volume and package geometry

Where it gets more complicated:

Vacuum-sealed packages are the most common edge case. If the package was sealed under vacuum at production, there’s no internal headspace to drive bubble formation. Without air introduction, a vacuum-sealed package may appear to pass D3078 testing even if a defect is present, because there’s no gas to push out. The VAC Attachment addresses this with a brief air injection before testing. As noted above, this makes the test destructive, so plan your sample sizes accordingly.

Liquid-filled packages with minimal air space present a similar challenge. Dense product can both reduce headspace and physically plug small openings. For these formats, ASTM F2096 (internal pressurization) is often worth evaluating. You supply the test pressure rather than relying on existing headspace gas.

Semi-rigid trays with film lids can be tested with D3078 if headspace is adequate, but ASTM F2096 is frequently the more appropriate method for tray formats.

D3078 vs. F2096 vs. F1140 vs. ISO 11607: Which Standard Do You Need?

Standard	Method Type	Package Type	Destructive?	What It Detects
ASTM D3078	Detection	Flexible packages with headspace	No	Gross leaks via bubble emission under vacuum
ASTM F2096	Detection	Trays and pouches	Yes	Gross leaks via internal pressurization; ~81% probability of detecting a 250 µm defect (round-robin data)
ASTM F1140	Burst / Creep	Flexible packages	Yes	Seal strength and burst pressure; measures force to failure, not leak location
ASTM D6653	Conditioning	Any package format	No	Not a leak detection method; simulates the pressure differentials packages experience during air shipment or high-altitude ground transport; must be paired with a detection method afterward
ISO 11607	System standard	Sterile barrier / medical packaging	N/A	Framework for sterile packaging integrity; references acceptable detection methods including D3078 and F2096

F1140 measures seal strength, not leak location — for the difference between the two, see our seal strength vs. seal integrity guide.

Sources: ASTM D3078-02, ASTM F2096-11, ASTM D6653, ASTM F1140, ISO 11607

A few things worth flagging directly:

D3078 and F2096 are not interchangeable. F2096 is destructive. The package must be punctured to insert the air supply and pressure monitor. It has published round-robin sensitivity data that D3078 does not. If your contract specifies F2096, D3078 does not satisfy it. If it specifies D3078, F2096 does not satisfy it. They are separate standards for different test configurations. For teams that need to run both, FlexPak’s FPIPA add-on enables ASTM F2096 internal pressurization testing on the same base unit, so one machine covers both standards. For a deeper look at when and how to use F2096, see our ASTM F2096 practical uses guide.

D6653 is a conditioning method, not a detection method. It reveals existing weaknesses rather than creating defects. If your distribution chain includes air freight or high-altitude ground transport, the appropriate workflow is to run D6653 first to simulate those altitude-driven pressure changes, then run D3078 afterward to detect any leaks that resulted. They complement each other; neither replaces the other. The FPFAT fully-automatic controller stores altitude simulation recipes (#25–50) alongside bubble emission recipes (#1–24), so teams running both D6653 and D3078 manage everything from a single controller.

ISO 11607 doesn’t name a single test method. It’s a sterile barrier systems framework for medical device and pharmaceutical packaging. When a contract requires ISO 11607 compliance, your team selects an appropriate detection method, often D3078 or F2096, as part of your validation protocol. For a detailed look at how this framework connects to FlexPak equipment, see our seal integrity test methods guide.

Equipment and Setup for ASTM D3078 Testing

Running D3078 doesn’t require a room full of instrumentation. The core equipment is straightforward:

• A transparent vacuum chamber with a hold-down plate (the package must remain visible throughout the test)
• A vacuum pump capable of controlled, consistent draw rates (approximately 1 in. Hg/s)
• A vacuum gauge for accurate setpoint measurement, which is what makes results repeatable
• Immersion fluid (water, water with wetting agent, denatured alcohol, or mineral oil), validated for your product
• A timer to control the hold phase

What separates a reliable QA program from a compliance checkbox is repeatability: saved test recipes per SKU, consistent vacuum setpoints and hold times, and performance qualification when you first establish or change a protocol.FlexPak leak detectors ship calibrated and ready to use, with a typical lead time of 3–4 weeks. No calibration or IT setup required on arrival.

If you’re setting up a new D3078 protocol, our article on common bubble leak testing mistakes covers the field errors we see most often and how to avoid them before they end up in your audit records. For a broader look at how ASTM standards apply to food packaging programs, see our ASTM packaging standards guide.

Frequently Asked Questions

What is the difference between ASTM D3078 and ASTM F2096?

ASTM D3078 draws vacuum to make headspace gas escape through any leak point, producing visible bubbles. No puncture required. ASTM F2096 punctures the package to insert an air supply and pressure monitor, then inflates it underwater and observes for bubbles at failure points. D3078 is non-destructive; F2096 is destructive. F2096 has published round-robin data supporting approximately 81% probability of detecting a 250 µm defect. D3078 does not specify sensitivity in microns.

Can ASTM D3078 be used for vacuum-sealed packages?

Not without air introduction first. Vacuum-sealed packages contain no headspace, so there’s no internal gas to drive bubble formation under vacuum. FlexPak’s VAC Attachment addresses this with a brief air injection before testing. Without it, a vacuum-sealed package may false-pass regardless of whether a defect is present. Important: testing with the VAC Attachment is a destructive process – the package is punctured for air injection and cannot be resealed. Plan your sample sizes accordingly.

What vacuum level should I use for ASTM D3078 testing?

There is no single universal answer. Vacuum levels are typically selected based on package strength, headspace volume, product behavior, and shipping conditions, and are validated during process setup. A common approach is to find your package’s seal failure point, then test at approximately 90% of that vacuum level. Many North American manufacturers use around 12 inHg as a starting benchmark for domestic air freight conditions.

Does ASTM D3078 detect microleaks?

No. D3078 is designed for gross leak detection only. Very small leaks, particularly channel defects near or below the method’s sensitivity threshold, may not produce a visible, steady bubble stream under standard test conditions. If your application requires higher sensitivity than D3078 provides, the right test method depends on your specific package type and quality requirements. Our team can help you evaluate the options – book a 15-minute call here.

Is ASTM D3078 required for food packaging?

D3078 is not universally mandated by regulation, but food safety frameworks such as HACCP and GMP commonly lead QA teams to include package integrity testing as part of their quality programs. Many retailers and co-packer agreements specify D3078 directly. Whether it applies to your operation depends on your customer contracts, your HACCP plan, and your product risk assessment.

The Bottom Line

ASTM D3078 is one of the most practical tools in a flexible packaging QA program. It’s fast (results in 30 seconds or less), non-destructive for standard headspace packages, and it shows you exactly where a leak is, not just whether one exists. But it has real limits: it requires headspace, its sensitivity varies based on conditions your team controls, and it is not a substitute for F2096 or other methods when those are specifically required.

Knowing the method, not just the standard number, is what turns a compliance requirement into a genuine quality program.

About the Author: Gordon Bruce, Director of Sales, FlexPak Leak Detectors. Gordon has spent years helping QA managers, quality engineers, and plant managers at food, pharmaceutical, and consumer goods manufacturers implement package integrity testing programs.