ASTM D3078 · Bubble emission leak testing
ASTM D3078 leak tester: vacuum chambers for bubble emission testing of flexible packaging
An ASTM D3078 leak tester is a vacuum chamber in which a flexible package is submerged in liquid and exposed to a controlled vacuum: a leak shows up as a steady stream of bubbles. DVACI designs and manufactures acrylic vacuum chambers (the CDV range) and control modules for exactly this test method, with regulated vacuum, a programmable hold time, clear walls on every side, and internal sizes from a single sachet to a case-sized bag. This page covers what the standard requires, which equipment features matter in practice, how to configure a chamber for your package, and how to define a vacuum level and time you can defend in an audit.
What ASTM D3078 requires
ASTM D3078, Standard Test Method for Determination of Leaks in Flexible Packaging by Bubble Emission, covers the detection of gross leaks in flexible packaging that contains a headspace gas. The package is immersed in a liquid inside a vacuum chamber, the pressure in the chamber is lowered, and the operator watches the package. A steady progression of bubbles from one point indicates a leak. Isolated bubbles that rise once and stop are usually air trapped in folds, gussets, or the seal area.
Three points in the standard shape the equipment you need.
- Headspace is required. The gas inside the package is what escapes through a defect. Packages with little or no headspace, such as vacuum-packed products or liquid-filled sachets, call for a different approach, typically internal pressurization per ASTM F2096.
- Sensitivity is limited. The standard states a sensitivity limit of about 1 × 10−5 atm·cm³/s and warns that small leaks may not be detected: product viscosity, entrapped air, and the package material can block flow through a small opening. The detectable leak size depends on the product, the material, and the test parameters you select.
- Vacuum level, hold time, and liquid are not fixed. The standard calls for a chamber that withstands roughly one atmosphere of differential pressure, a vacuum gauge, and an immersion fluid that does not degrade the package, with samples and fluid at room temperature. The actual vacuum and time are chosen by the user, which is why they have to be established on your own packages.
In the vocabulary of USP <1207.2>, bubble emission is a probabilistic leak test method: the probability of detecting a given defect is below 1 and depends on the test conditions. This does not make the method less useful. It means its role, its limits, and its parameters must be documented inside your package integrity program rather than assumed.
ASTM D3078 test equipment: the features that matter
Any sealed box connected to a vacuum source will produce bubbles. Equipment that supports a repeatable, documented D3078 test needs a little more.
Vacuum level control and readout
The vacuum level is the main test parameter. The chamber must reach the target without overshoot, hold it without drift, and display it in the unit written in your procedure. DVACI control modules read vacuum with a digital gauge over 0 to −100 kPa (0 to −29.5 inHg / 0 to −14.5 psi). Module S adds an electronic vacuum regulator with a lockable setpoint, so an operator cannot change the vacuum between two tests. Module P stores the setpoint inside a named test recipe.
Hold time
Bubbles from a small channel can take tens of seconds to appear. A timer that keeps the vacuum for the programmed duration and vents the chamber automatically takes the stopwatch out of the operator's hands. Module S (timer and venting solenoid valve) and Module P (multi-step profiles, up to 4 vacuum/time steps) both do this. Module M is fully manual: a regulation valve, a digital gauge, and the operator's watch.
Visibility
The result of a D3078 test is what the operator sees. CDV chambers are built from clear acrylic (PMMA) with 30 mm or 50 mm (1.2 in or 2 in) walls, so the package can be observed from the sides and from the top under normal lab lighting without opening the chamber.
Chamber size and immersion volume
The package must be fully submerged, in practice about 25 mm (1 in) below the surface, with clearance around it so that every seal remains visible. Internal dimensions, not external ones, decide which chamber fits your package. Remember that a package with headspace inflates under vacuum.
Vacuum source: two different limits
Two limits apply, and they should not be confused. The first is the limit of the vacuum generator. CDV chambers generate vacuum with a built-in Venturi that runs on compressed air (185 L/min at 5 bar, i.e. 6.5 CFM at 72 psi; maximum inlet pressure 6 bar / 87 psi), reaching −750 mbar (−22.1 inHg) and up to −800 mbar (−23.6 inHg) in favourable conditions. No vacuum pump is needed if the lab has compressed air. For a deeper vacuum, or for sites without an air line, an optional electric pump is available: a two-stage rotary pump reaching −950 mbar (−28.1 inHg) or an oil-free pump reaching −900 mbar (−26.6 inHg).
The second is the structural limit of the chamber, which is a property of the model and is given in the specification table below. A pump able to pull −950 mbar does not raise the limit of a chamber rated −750 mbar.
All vacuum figures on this page are given at sea level. A vacuum gauge reads relative to the local atmosphere, so the achievable vacuum falls with altitude; at elevation the values must be checked on site.
Venting and safety
Automatic venting at the end of the hold time (Module S and Module P) returns the chamber to atmospheric pressure in a controlled way. Reaching the setpoint progressively also avoids bursting a weak seal before the observation starts, which would turn a seal-strength event into a false leak.
Configurations recommended by package size
The table below is a sizing guideline. Leave clearance for water, the hold-down grid, and inflation of the package under vacuum; when in doubt, send the package dimensions and DVACI will confirm the model.
| Packages (examples) | Typical package footprint | Recommended chamber | Internal dimensions (L × W × H) | Typical module |
|---|---|---|---|---|
| Sachets, stick packs, small pouches, blister cards | up to ~230 × 150 mm (9 × 6 in) | CDV2 | 280 × 200 × 200 mm (11 × 8 × 8 in) | Module M or S |
| Stand-up pouches, retort pouches, snack bags, medical pouches | up to ~400 × 250 mm (16 × 10 in) | CDV3 | 450 × 300 × 250 mm (18 × 12 × 10 in) | Module S or P |
| Large pouches, pillow bags, MAP trays, several units per cycle | up to ~450 × 300 mm (18 × 12 in) | CDV4 or CDV4+ | 500 × 350 × 350 mm (20 × 14 × 14 in) | Module S or P |
| Bulk bags, large trays, multi-pack cycles | up to ~550 × 450 mm (22 × 18 in) | CDV5 (floor stand) | 600 × 500 × 400 mm (24 × 20 × 16 in) | Module S or P |
| Case-sized bags, bag-in-box, very large formats | up to ~750 × 550 mm (30 × 22 in) | CDV6 (floor stand) | 800 × 600 × 500 mm (31 × 24 × 20 in) | Module S or P |
Two details matter when choosing between CDV4 variants. The CDV4, with 30 mm walls, is deliberately limited to −750 mbar (−22.1 inHg): customers run repeated tests, and holding a deeper vacuum on a 30 mm panel accelerates material fatigue. The CDV4+ (part reference CDV4-50, 50 mm walls) reaches −950 mbar (−28.1 inHg) and is the version DVACI recommends for heavy daily use.
How an ASTM D3078 test works with a CDV chamber, step by step
- Condition. Bring the samples and the immersion liquid to room temperature. The standard asks for equilibrium with the room, because temperature changes move the headspace gas and distort the result.
- Fill. Fill the chamber, or an inner tank placed in the chamber, with enough water to cover the package by about 25 mm (1 in). A small amount of wetting agent can reduce bubbles clinging to the film (check compatibility with the package material).
- Load. Place the package under the hold-down grid so that it stays submerged and all seals are visible. Note the orientation; a procedure may require testing more than one face.
- Close and start. Close the lid. With Module S, press START: the regulator draws vacuum to the setpoint and the timer begins. With Module P, select the recipe and start the test; the profile runs on its own.
- Observe. During the hold time, look for a steady stream of bubbles from a single point. Note the location: seal, corner, body, fitment, or gusset.
- Vent. The module vents automatically at the end of the hold time (with Module M, the operator opens the valve).
- Record. Write down the vacuum, time, result, and defect position.
- Confirm when needed. A suspected leak can be confirmed by repeating the test or by internal pressurization (ASTM F2096) with the Internal Pressurization Kit, which targets the suspect area directly and works without headspace.
Defining the vacuum level and hold time with good and defective samples
ASTM D3078 leaves vacuum and time to the user. The defensible way to set them is an experiment on your own packages, not a value copied from another product or another plant.
Step 1 — Prepare control defects. Build packages with known leak sizes. DVACI supplies 50 µm tungsten wire and calibrated pins of 150 µm and 250 µm for this purpose. Sealing a wire into the seal and withdrawing it leaves a channel of known diameter; a pin creates a hole of known size in the film. Prepare several units per defect size, plus a set of intact packages from the same lot.
Step 2 — Find the vacuum the package tolerates. Raise the vacuum stepwise on intact packages until a seal opens or the package deforms excessively. Your usable range sits below that limit, with a safety margin.
Step 3 — Scan vacuum and time. Test the defective packages at several vacuum levels and hold times. Count how many units of each defect size are detected. A 250 µm hole is usually detected quickly; the 50 µm channel is where the method reaches its limit, and where the results show the probabilistic nature of the test.
Step 4 — Select and confirm. Choose the lowest combination of vacuum and time that reliably detects the smallest defect that matters for your product, then confirm it on a larger run of intact and defective packages. This run becomes the evidence behind your OQ/PQ documentation.
Step 5 — Lock and document. Program the setpoint (lockable on Module S, recipe-protected on Module P) and write the parameters, the chamber model, the water temperature, and the acceptance criterion into the SOP.
As an order of magnitude, flexible packages with headspace are often tested between −300 and −600 mbar (−8.9 to −17.7 inHg) for 30 to 60 seconds. Treat these figures as starting points for the experiment above, not as specifications: a thin retort pouch and a stiff laminated bag will not share the same values.
Documentation, traceability, and calibration
- Readout and units. Module S displays vacuum in mbar, inHg, mmHg, psi, kPa, or MPa, so the SOP and the screen use the same unit and nobody converts in their head.
- Test records. Module P (PLC with ORION OS, 4.3-inch color touchscreen) stores named test recipes, runs multi-step profiles, and offers two user levels. An optional thermal or dot-matrix printer and a barcode reader link the record to the lot.
- 21 CFR Part 11. With ORION OS and the CFR21 software option, which runs on a Windows PC alongside the instrument, the system meets 21 CFR Part 11 requirements: audit trail, individual user accounts through LDAP / Active Directory, PDF export with electronic signature, time-stamping and record integrity. The CFR21 option is required for this; without it, ORION OS does not provide nominative electronic signatures. A point-by-point breakdown of the requirements is available on request.
- Calibration. The DVACI calibration kit includes a reference gauge (−1 to +1 bar) with a traceable certificate (EMA accreditation, ILAC arrangement). The vacuum sensor is checked by direct comparison at −150, −300, −450, −600, and −700 mbar (−4.4, −8.9, −13.3, −17.7, −20.7 inHg), with a maximum accepted sensor error of 2 % of full scale, i.e. 20 mbar.
- Qualification. IQ/OQ/PQ documentation is available for the CDV range (exact scope per configuration to confirm with DVACI).
Specifications of DVACI ASTM D3078 test equipment
All vacuum values are given at sea level.
| Item | CDV2 | CDV3 | CDV4 | CDV4+ (CDV4-50) | CDV5 | CDV6 |
|---|---|---|---|---|---|---|
| Internal dimensions (L × W × H) | 280 × 200 × 200 mm / 11 × 8 × 8 in | 450 × 300 × 250 mm / 18 × 12 × 10 in | 500 × 350 × 350 mm / 20 × 14 × 14 in | 500 × 350 × 350 mm / 20 × 14 × 14 in | 600 × 500 × 400 mm / 24 × 20 × 16 in | 800 × 600 × 500 mm / 31 × 24 × 20 in |
| Wall thickness (acrylic) | 30 mm / 1.2 in | 30 mm / 1.2 in | 30 mm / 1.2 in | 50 mm / 2 in | 50 mm / 2 in | 50 mm / 2 in |
| Weight | 19 kg / 42 lb | 38 kg / 84 lb | 42 kg / 93 lb | 70 kg / 154 lb | 105 kg / 231 lb | 175 kg / 386 lb |
| Max vacuum with Venturi | −750 mbar / −22.1 inHg | −750 mbar / −22.1 inHg | −750 mbar / −22.1 inHg | −750 mbar / −22.1 inHg | −750 mbar / −22.1 inHg | −750 mbar / −22.1 inHg |
| Max vacuum with electric pump | −950 mbar / −28.1 inHg | −950 mbar / −28.1 inHg | −750 mbar / −22.1 inHg (chamber limit) | −950 mbar / −28.1 inHg | −950 mbar / −28.1 inHg | −750 mbar / −22.1 inHg (chamber limit) |
| Mounting | Bench | Bench | Bench | Bench | Floor stand | Floor stand |
The chamber limit shown for the CDV4 and the CDV6 is a deliberate design choice, not the limit of the pump: both models are capped at −750 mbar because customers run repeated test cycles, and material fatigue rises sharply beyond that value.
Control modules (common data): external box 350 × 350 × 170 mm (13.8 × 13.8 × 6.7 in), 8 kg (17.6 lb), 100–240 V 50/60 Hz, Venturi included, compressed air 185 L/min at 5 bar (6.5 CFM at 72 psi), maximum inlet 6 bar (87 psi), 8 mm air hose, 12 mm vacuum hose and 4 mm sensor hose to the chamber.
| Module | Control | Vacuum readout | Timer / venting | Records |
|---|---|---|---|---|
| Module M (DV-CONT-M-01) | Manual regulation valve | Digital gauge, ±5 mbar, −100 kPa to 0 | Manual | None |
| Module S (DV-CONT-ST-01) | Electronic regulator, lockable setpoint, START/STOP | SMC ZSE20A-Y digital pressure switch, 0 to −101 kPa; units mbar, inHg, mmHg, psi, kPa, MPa | Timer, automatic venting solenoid | None (manual log) |
| Module P (PLC, ORION OS) | 4.3-inch color touchscreen, recipes, 2 user levels | Digital, stored per recipe | Multi-step profile up to 4 vacuum/time steps, automatic venting | Test records; optional printer, barcode reader, CFR21 software option |
Applications of an ASTM D3078 leak tester
- Food and beverage: pouches, snack bags, coffee bags with headspace, MAP trays with lidding film; start-of-batch checks on sealing machines and periodic QC.
- Pharma and nutraceutical: pouches and sachets with headspace, secondary packaging. Blister packs are usually tested by dye immersion.
- Medical devices: nonporous pouches and trays with headspace. Porous (spunbonded polyolefin) packaging calls for other methods such as ASTM F2096 or ASTM F1929.
- Consumer goods, cosmetics, chemicals: sachets, pods, flexible refill packs.
- Converters and sealing-machine builders: seal validation, development of sealing parameters, material comparisons.
- Test laboratories: contract testing to ASTM D3078, with documented parameters per client package.
Services
DVACI and its distributors provide installation and start-up, operator training (on site or remote), IQ/OQ/PQ documentation, traceable calibration (initial and periodic), preventive maintenance plans, spare parts (gaskets, valves, sensors), remote support, and training videos. Which of these are delivered locally depends on your country; the contact page routes your request to the right team.
Frequently asked questions
What is the difference between ASTM D3078 and ASTM F2096? ASTM D3078 applies vacuum to a package submerged in liquid and relies on the headspace gas escaping through a defect. ASTM F2096 injects air into the package through a needle and septum (internal pressurization) while it is submerged, so it works on packages with little or no headspace, such as vacuum packs. Both are bubble tests, both are destructive, and both are classified as probabilistic methods.
What vacuum level does ASTM D3078 specify? It does not fix one. The standard requires a chamber able to withstand about one atmosphere of differential pressure, a vacuum gauge, and a liquid that does not degrade the package; vacuum level and hold time are chosen by the user. DVACI recommends defining them with intact and deliberately defective packages, then locking the setpoint in Module S or in a Module P recipe.
Can an ASTM D3078 leak tester detect micro-leaks? No. The standard itself states a sensitivity limit of about 1 × 10−5 atm·cm³/s and warns that small leaks may not be detected because product, entrapped air, or the film can block flow through a small opening. The method targets gross leaks and is probabilistic per USP <1207.2>. For smaller defects, deterministic methods such as vacuum decay (ASTM F2338) are used alongside it.
Is the ASTM D3078 test destructive? Yes. The package is submerged in water under vacuum, so the sample and its content are normally not returned to the line, even when no leak is found. For a non-wetting go/no-go check, a dry test in the same CDV chamber (observing package inflation and stability under vacuum) is possible, but it is less sensitive than immersion and must be validated separately.
Does the chamber need a vacuum pump? Not necessarily. CDV chambers generate vacuum with a built-in Venturi fed by compressed air (185 L/min at 5 bar, or 6.5 CFM at 72 psi), reaching about −750 mbar (−22.1 inHg) at sea level. An optional electric pump (two-stage rotary to −950 mbar / −28.1 inHg, or oil-free to −900 mbar / −26.6 inHg) is available for a deeper vacuum or for sites without a compressed-air line. All of these values are given at sea level and fall with altitude.
Which chamber size do I need for my package? Compare the package footprint, including inflation under vacuum, with the internal dimensions of the chamber: CDV2 for sachets and small pouches, CDV3 for stand-up pouches, CDV4 and CDV4+ for trays and several units per cycle, and the floor-stand CDV5 and CDV6 for bulk bags and large trays.
Can the same equipment be used for ASTM D6653 altitude simulation? Yes. ASTM D6653 exposes a package to a vacuum that reproduces the pressure at a given altitude for a given time, usually without water. A CDV chamber with Module S or Module P runs that profile, and Module P can chain up to four vacuum/time steps.
How do I document ASTM D3078 results for an audit? Record the chamber and module, the vacuum setpoint and hold time, the water temperature, the sample identification, the result, and the defect position. Module P stores recipes and test records; a printer or barcode reader can be added, and the CFR21 software option provides the 21 CFR Part 11 controls.
Request a quote for your ASTM D3078 test equipment
Send the package dimensions, the material, whether the package has headspace, and the number of tests per day. DVACI recommends the chamber and module, replies within four business hours and sends a quote within three business days of receiving the information.
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