By Tanner Vandenberg, CEO, FlexPak Leak Detectors Inc.
If your seal fails, it won’t whisper. It bubbles.
That is the advantage of a gross leak bubble tester. It turns an invisible packaging flaw into a bubble stream you can watch, so you see exactly where a seal fails, in 30 seconds or less.
FlexPak builds two bubble leak testers: the FlexPak Leak Detector, a vacuum chamber that runs ASTM D3078 bubble emission, and the FPIPA, which runs ASTM F2096 internal pressurization for porous and sterile-barrier medical packs. This page covers both: how each one works, which packages each one tests, the specs, and how to choose. For the test standard in detail, see our guide to the ASTM F2096 standard.
What Is a Gross Leak Bubble Tester?
A gross leak bubble tester submerges a sealed package in water and creates a pressure difference across the package wall. Air escapes through any leak large enough to matter and forms a steady stream of bubbles at the failure point. The result is visual, and it shows you the leak location, not just a pass or fail.
There are two ways to create that pressure difference, and each has its own ASTM standard. ASTM F2096 pressurizes the package from the inside through a puncture. ASTM D3078 draws a vacuum around the package in a sealed chamber. Both come from ASTM Committee F02 on flexible barrier packaging, and both are gross leak test methods.
Sensitivity is stated differently for each. F2096 detects a 250 micrometer defect with approximately 81% probability, based on the standard’s five-lab round robin on Tyvek packaging. D3078 states its sensitivity as a leak rate, about 1 x 10-5 atm cm3/s or less sensitive, and it needs headspace gas in the package to work. Neither figure is a guarantee for every package: vacuum or pressure level, headspace, product, and material all change what a gross leak test will catch.
Which Bubble Leak Tester Do You Need?
Pick the bubble leak tester by package type. If the package has headspace gas, such as a snack bag, pouch, or film-sealed tray, use a vacuum chamber tester running ASTM D3078. If the package is vacuum-sealed or has little headspace, use the same chamber with an attachment that adds air before the test. If the package is porous or a sterile barrier, such as a Tyvek medical pouch, use an internal pressurization tester running ASTM F2096.
| Your package | Test method | FlexPak equipment |
|---|---|---|
| Flexible packs with headspace: snack bags, pouches, film-sealed trays | ASTM D3078 bubble emission | FlexPak Leak Detector |
| Vacuum-sealed or low-headspace packs: meat, cheese, protein | ASTM D3078 with air added first | Leak Detector with the VAC Attachment |
| Semi-rigid packages, rigid trays, and rigid containers | ASTM D3078 bubble emission | FlexPak Leak Detector |
| Porous and sterile-barrier medical packs: Tyvek pouches | ASTM F2096 internal pressurization | FPIPA, standalone or on a Leak Detector |
| Packages that ship by air or over mountain routes | ASTM D6653 altitude conditioning, then D3078 to detect | Leak Detector with the FPFA-T controller |
Most food lines need the first two rows. F2096 is built for porous medical packaging and applies to food only in narrow porous-material cases. D6653 is a conditioning method: it stresses the package the way altitude does, and a detection test such as D3078 then shows what failed.
Why Bubble Testing Still Leads the Industry
It is fast, visual, and simple to train. A typical test takes 30 seconds or less once the setpoint is reached. Many electronic leak testers tell you IF a package leaks. A bubble tester shows you WHERE, so you can trace the failure back to the seal bar, the film, or the closure.
You will know in moments:
- No bubbles means package integrity is confirmed under the test conditions.
- Continuous bubbles mean a leak is detected, at the spot they come from.
That clarity is why QA teams still run bubble tests every shift, as a frontline safeguard against costly recalls.
How a Gross Leak Bubble Tester Works
Internal pressurization, ASTM F2096 (FPIPA)
- Insert the puncture device through a septum on the sealed package to introduce air.
- Submerge the package so water covers it by about one inch (25 mm).
- Raise internal pressure to the test pressure set for that package. The standard’s pressure system covers 0 to 50 mbar (0 to 20 in. H2O), and the test pressure is established with a control package carrying a known defect.
- Watch for a steady stream of bubbles at seals, corners, and seams.
Exercise extreme caution when handling the needle at all times. The test is destructive, because the package is punctured, and it is a pass or fail method, not a leak-rate measurement.
Vacuum chamber bubble emission, ASTM D3078 (FlexPak Leak Detector)
- Place the sealed package in the water-filled chamber and close the lid.
- Pull the vacuum. The package expands and stresses every seal.
- Hold at the setpoint, typically about 30 seconds, and watch for a steady bubble stream.
- Release the vacuum and check the package for water that got in.
A steady stream from the same spot means the package has failed. Bubbles that appear once and stop are trapped air, not a leak. Setup, vacuum levels, and the most common false passes are covered in our guide on how to run a bubble leak test.
What Packages Can Be Tested
- Flexible pouches, bags, and film-sealed trays (D3078)
- Vacuum-sealed meat, cheese, and protein packs (D3078 with the VAC Attachment)
- Sachets and stick packs, many at once with the Stick Pack and Sachet Fixture
- Semi-rigid packages, rigid trays, and rigid containers
- Liquid-filled packages (add-ons required)
- Tyvek and other porous medical and pharmaceutical pouches (F2096 with the FPIPA)
FlexPak chambers run from a tabletop unit for packages up to 10 x 7 x 5 inches to a floor-stand unit for packages up to 38 x 21 x 17 inches, so a 1 oz sachet and a 10 kg bag of pet food can both be tested.
Bubble Leak Tester Specs at a Glance
The bubble leak test equipment below is what ships from FlexPak today. Model names give a chamber’s inside dimensions: the FP181210 is 18 inches wide, 12 deep, and 10 high.
| FlexPak Leak Detector | FPIPA | |
|---|---|---|
| Test standard | ASTM D3078; ASTM D6653 with the FPFA-T controller; ASTM F2096 with the FPIPA | ASTM F2096 |
| Method | External vacuum, package submerged | Internal pressurization through a septum, package submerged |
| Sizes | Seven chambers, from the FP110808 tabletop (packages up to 10 x 7 x 5 in, 250 x 180 x 130 mm) to the FP392220 floor-stand (up to 38 x 21 x 17 in, 965 x 533 x 431 mm) | Fits all base model Leak Detectors, or runs standalone |
| Control | Manual as standard, FPSA-T semi-automatic, or FPFA-T fully automatic | Self-regulating pressure control, 0 to 20 in. H2O, simple on and off with manual adjustment |
| Construction | Stainless steel and acrylic | Assembly for the Leak Detector |
| Utilities | Compressed air as standard, or the Electric Vacuum Pump from a 120V or 240V outlet; water to fill the tank and a drain | Not compatible with the FPSA or FPFA controllers or the Electric Vacuum Pump |
| Lead time | Tabletop units typically in stock | Add-ons: minimum one week |
Add-Ons That Change What You Can Test
- VAC Attachment. Injects a controlled burst of air so vacuum-sealed and low-headspace packs can be bubble tested. Without it, there is no air in the pack to escape and leaks go undetected.
- FPIPA. Adds ASTM F2096 internal pressurization for porous and Tyvek medical packaging, using the same chamber.
- FPSA-T semi-automatic controller. Two preset tests that control target vacuum and hold time automatically, so every operator runs the same test.
- FPFA-T fully automatic controller. Up to 24 test profiles, pass or fail results logged automatically for the audit trail, and ASTM D6653 altitude conditioning.
- Electric Vacuum Pump. Runs from a standard outlet when compressed air is not available, and makes the unit quieter and portable.
Bubble Emission Test Methods for Gross Leak Detection
| Standard | Method | Typical use | Stated sensitivity |
|---|---|---|---|
| ASTM F2096 | Internal pressurization under water | Porous and sterile-barrier medical packaging (Tyvek) | 250 μm at approximately 81% probability (round robin) |
| ASTM D3078 | Vacuum chamber bubble emission | Flexible packaging with headspace: food, consumer goods | Leak rate of about 1 x 10-5 atm cm3/s or less sensitive |
ASTM F2096 uses internal pressurization, while ASTM D3078 uses an external vacuum. Each needs different equipment and setup, which is why the FPIPA is a separate assembly. Medical device teams often use F2096 as part of an ISO 11607 packaging validation; food teams generally run D3078. For the full method breakdown, see the ASTM F2096 standard guide.
When to Use Bubble Testing vs Other Methods
Use a gross leak bubble tester when you need:
- Rapid, visual proof of seal integrity, with the leak location
- Daily line checks or operator verification
- Documented ASTM test results for QA or audits
Bubble testing is a gross leak method. For smaller defects, or for container closure integrity validation on sterile injectables, USP <1207> generally favors deterministic methods such as vacuum decay, which FlexPak does not perform. Many QA programs use both: bubble tests for routine line checks, a deterministic method for final validation.
Common Operator Mistakes That Skew Results
Even a simple test can go wrong without consistency. The most common errors:
- Over-pressurizing or pulling too much vacuum and rupturing a good seal, a false fail
- Testing vacuum-sealed packs without adding air first, a false pass
- Insufficient water coverage or lighting
- Using uncalibrated pressure or vacuum gauges
- Forgetting to reseal the puncture site before pressurizing
The fix is a controlled setpoint. The FPIPA self-regulates internal pressure, and the FPSA-T and FPFA-T controllers hold vacuum and time the same way on every test, so results stay repeatable from shift to shift.
The Role of Bubble Testing in Compliance
Customers and auditors commonly expect documented proof that packaging keeps a sterile or contamination-free barrier. For medical devices, ISO 11607 covers packaging validation, and F2096 and D3078 are among the ASTM methods teams use within it. Documenting each test (date, operator, package ID, test pressure or vacuum, pass or fail, and leak location) builds the traceability auditors look for. The FPFA-T logs pass or fail results automatically.
What to Look for When Choosing a Bubble Tester
- Chamber size: match the chamber to the largest package you test.
- Pressure or vacuum control: a stable setpoint with a visible gauge. For F2096, control in the 0 to 50 mbar range.
- Visibility: clear chamber walls and good lighting, so faint bubble streams are not missed.
- Versatility: add-ons for vacuum-sealed, liquid-filled, and porous packs.
- Traceability: automatic data logging if you are audited.
- Food-safe build: stainless steel and acrylic that cleans easily.
- Support: a direct line to the people who built the unit. FlexPak includes unlimited expert calls and free virtual training.
Real-World Impact: Preventing Recalls Before They Happen
A bubble leak testing machine earns its place on the line by catching seal problems before a lot ships, not after a customer complaint. Teams that run it every shift tend to keep it for years. One QA coordinator put it this way:
“We have a tank purchased in 2013 and it’s still going, used every day. It’s become an essential part of our quality system.”
Kurt L., Quality Control Coordinator, Packall Packaging Inc.
How to Get a Quote for a Bubble Leak Tester
- Step 1: Send your package dimensions, package type, and the ASTM method your customer or auditor asks for.
- Step 2: We recommend the chamber size and only the add-ons you need.
- Step 3: Get your quote in 24 hours.
Every unit is built in Ontario, Canada and ships to U.S. buyers with no tariff exposure under CUSMA. Get your quote in 24 hours.
Frequently Asked Questions
What is the difference between a bubble leak tester and a gross leak bubble tester?
Bubble leak tester is the general name for any tester that finds leaks by watching for bubbles under water. Gross leak bubble tester usually means an ASTM F2096 internal pressurization setup, because the F2096 standard is titled as a gross leak bubble test. Both find gross leaks, not the smallest defects.
Can FlexPak test my packages for me?
No. FlexPak does not offer in-house testing services. Send your package details and the team will recommend the unit and add-ons that fit.
Does a bubble leak tester work on vacuum-sealed packages?
Yes, with the VAC Attachment. A vacuum-sealed pack has no air inside to escape, so the attachment adds a controlled burst of air before the vacuum is pulled. Without it, leaks in vacuum-sealed packs go undetected.
What does a bubble leak tester need to run?
Standard FlexPak units have no power requirement but need compressed air. Units with the Electric Vacuum Pump need a 120V or 240V outlet instead. Every unit needs water to fill the tank and a way to drain it afterward. A dedicated water line is not required.
How long is the lead time?
Tabletop units are typically in stock and ready to ship. Floor-stand units and add-ons have a minimum lead time of one week.
The Bottom Line
Every bubble tells you something, and the best result is none at all. A bubble leak tester gives you visual proof that your seals hold, and it shows you exactly where they don’t.
See the FlexPak Leak Detector, see the FPIPA, or get your quote in 24 hours.