Seal Integrity Testing System

A seal integrity testing system ensures that cases and transport containers are reliably protected against the ingress of water, dust and contaminants. In practice this concerns aluminium cases, plastic cases, transport containers as well as specialist solutions such as the X-PCK Backpack Case and the Mobile Work Table in a Case. Especially in fields such as medical technology, electrical engineering, metrology, mechanical engineering and professional trades, reproducible leak-tightness is a key quality characteristic, because equipment, samples, measuring instruments or mobile workstations must be transported and used while maintaining their function. In a specialized manufactory for B2B cases like KKC Koffer GmbH, leak-tightness testing is an integral part of development, production and final inspection. The sealing effect is not considered in isolation: latches, hinges, sealing profiles, pressure equalization elements, cable feed-throughs, foam inlays and even branding elements interlock by design and influence both testability and test results.

Definition: What Is a Seal Integrity Testing System?

A seal integrity testing system is a test rig including test procedures, sensors and fixtures used to verify a product’s tightness against defined media and pressure differentials. For cases, transport containers and mobile enclosures this means: the system generates overpressure or vacuum, measures pressure decay or flow, or uses test gases to reliably determine leak rates. Complementary equipment includes test chambers, adapters, sealing tools and calibration leaks to enable process-safe testing of different formats—from compact equipment cases to large-volume transport containers. The goal is a reproducible statement as to whether the required protection rating (e.g., against splashing water or temporary submersion) is achieved and whether the design—including sealing profiles and add-on components—performs consistently in series production.

Operating Principle and Test Methods

For cases, the X-PCK Backpack Case, aluminium cases, plastic cases, transport containers and specialized solutions there are several established test methods. Selection depends on volume, desired protection level, required strength of evidence and cycle time.

Pressure Decay and Differential Pressure Testing

The test item is brought to a defined positive or negative pressure level. A seal integrity testing system monitors pressure decay over time and calculates a leak rate. Advantages: short cycle times, good automation, scalable from small sample cases to large industrial cases. A properly matched fixture is important to preload the latches correctly and apply the intended compression force to the seal.

Flow Measurement

Under stable pressure conditions a mass flow or volumetric flow sensor measures the leakage flow. The method is suitable for larger leaks as well as end-of-line inspections when fast pass/fail decisions are required. For transport containers with large internal volume, flow measurement is often advantageous because measurement time scales less strongly with volume.

Vacuum Chamber and Water Bath

In an external chamber a pressure difference to ambient is generated, making leaks visible or measurable. Visual inspection (bubble formation) is illustrative but less objective and only of limited practicality in series production. For development purposes this enables localization of weak points on sealing profiles, hinges, rivets or cable feed-throughs.

Test Gas and Tracer Gas Methods

Tracer gases with highly sensitive detection enable identification of very small leak rates. They are helpful for special cases or devices that must meet particularly high sealing requirements. In case practice this method is used selectively, for example to validate prototype builds or safety-relevant assemblies.

Test Limits and Protection Ratings

Leak-tightness requirements are typically aligned to protection ratings against dust and water (e.g., splashproof through to dust- and waterproof). A seal integrity testing system translates these requirements into measurable thresholds, such as permissible leak rate or pressure drop per unit time. In practice it is important that identical protection claims can be substantiated by different methods; interpretation of measured values must always consider volume, temperature, material and test fixture.

Design Prerequisites for Cases and Transport Containers

Testability and passing seal tests begin in the design. A robust sealing line and reproducible preload are crucial, as is the set behavior of the seal over the lifecycle.

• Seal selection: EPDM, TPE or silicone with suitable Shore hardness, chemical resistance and temperature tolerance. Foam-in-place gaskets (FIPG) provide a uniform compression line.
• Geometry and tolerances: Homogeneous seal grooves, burr-free sealing faces and defined compression paths ensure reproducible test values.
• Latches and hinges: Sufficient latch points, uniform force distribution; hinges without unwanted gaps along the sealing line.
• Pressure equalization elements: Membranes enable pressure equalization while maintaining splash or immersion tightness; they must be included in testing.
• Cable and media feed-throughs: Gland fittings, connector plates and blanking plugs must be integrated into the sealing line and be testable.
• Fixture reference: Test adapters must replicate real closing forces; otherwise measurement deviations occur.

Material Selection: Aluminium Cases vs. Plastic Cases

Aluminium cases provide stable sealing faces and thermally well-conductive structures, but require care in joining processes (e.g., riveting, bonding, welding) to avoid capillary leak paths. Plastic cases from injection molding or thermoforming allow integral seal grooves and complex geometries; with large temperature fluctuations, thermal expansion must be considered to maintain seal preload.

Foam Inlays and Seal Integrity

Foam inlays influence sealing indirectly: they must not press components into the seal and should be specified as closed-cell grades when humid environments are expected. Drainage channels or spacer nubs prevent moisture from collecting on the seal. Adhesives must be selected so they do not migrate into the seal.

Test Concepts for Products by KKC Koffer GmbH

Depending on the product family, different seal integrity testing systems and test sequences are appropriate. Adjustments in the manufactory enable process-safe end-of-line testing as well as sampling-based inspection plans.

• Cases and industrial cases: Differential pressure testing with product-specific adapters and defined closing force; documented leak-rate thresholds per size.
• Transport containers: Flow measurement or vacuum chamber for large volumes; consider longer stabilization times.
• X-PCK Backpack Case: Testing of lid seal, zipper/seal-profile combinations and attachment points of the carrying systems; focus on splash water and dust protection under dynamic loading.
• Mobile Work Table in a Case: Functional openings, sockets, vents and cable feed-throughs are integrated via membrane or sealing concepts; testing covers the transport condition (closed) and—if required—the operation with service covers closed.
• Foam inlays: Co-tested regarding installation position; reference inlays to ensure constant preload conditions.
• Branding: Printing, embossing and nameplates are positioned so that no sealing lines are interrupted; if fixing points are required, they are executed with sealing washers or press-fit bosses and included in testing.

Mobile Work Table in a Case: Special Feed-throughs

This special case combines transport and in-use functions. Seals must safeguard the transport condition and also account for interfaces for power supply, data and ventilation. A seal integrity testing system therefore includes lockable operating flaps, filter membranes and patch-panel covers. Test sequences first verify base tightness, then the sub-areas. This preserves functionality without compromising the required protection rating during transport.

X-PCK Backpack Case in Focus

In hybrid backpack–case constructions, seam sealing, lid profiles and the sealed connection of shoulder straps play a central role. Test concepts usually specify splash protection, complemented by dust protection under practical conditions (e.g., construction site, field service). A robust seal integrity testing system simulates the preload of real use—including the slightly deforming strap load—to obtain realistic results.

Seal Integrity Testing in the Manufacturing Process

In manufactory practice, test stations are set up modularly: exchangeable adapters for different case formats, integrated leak standards for quick functional checks of the rig, defined stabilization times and temperature-compensated measurement strategies. For series items, 100% testing is common; for customer-specific small series, risk-based sampling plans are used. Results are assigned to lots, serial numbers or customer-specific identifiers.

Calibration and Maintenance

To ensure measurement capability, transmitters, reference leaks and pressure sensors are regularly checked and calibrated. Maintenance plans include seals of the test adapters, valves, hoses and the tightness of the test station itself. Environmental influences—especially temperature—are monitored, as they affect air density and thus measured values.

Documentation and Traceability

Typical contents are test date, method, thresholds, measured leak rate/pressure decay, release decision and reference to the specific configuration (e.g., installed seal material, number and type of latches, optional feed-throughs). This documentation supports quality evidence in regulated industries without replacing a legal case-by-case assessment.

Application Areas and Typical Requirements

Sealing is not an end in itself but derives from application and environment.

• Demo cases, sample cases, presentation cases: Primarily dust and splash protection, protection of surfaces and samples; short test times and stable closing force are important.
• Equipment cases, cases for measuring instruments: Protection against moisture and fine dust, often higher protection ratings; tests consider feed-throughs for interfaces.
• Transport cases, transport containers: High robustness, larger volumes; flow or vacuum chamber tests with longer stabilization times.
• Industrial cases, special cases: Project-specific thresholds and sometimes segmented sealing zones for assemblies.
• Cases for medical technology: Resistance of the seal to cleaning and disinfectants; reproducible tests with documented traceability.
• Cases for electrical engineering: Integration of pressure equalization elements and sealing of interface panels; testing in the closed transport condition.
• Professional cases for tradespeople and machine cases: Dust and splash protection under harsh conditions; focus on durable seals and latches.

Test Planning: Standards, Thresholds and Environmental Conditions

Protection ratings against dust and water are translated into measurable criteria in test plans. Thresholds are only meaningful if temperature, humidity and volume are considered. Seal integrity testing systems use stabilization phases, compensations and reference measurements to minimize influences. For mobile applications—such as altitude changes in air transport—pressure equalization elements are useful; they must be designed and tested so that water tightness within the target rating is maintained.

Temperature Cycling and Lifecycle

Temperature cycles cause material expansion and influence seal preload. Test concepts therefore sometimes include pre- or post-conditioning. The set behavior of the seal is also considered: repeated closing and opening changes compression force. A solid design ensures thresholds are maintained over the service life.

Error Sources and Corrective Actions

• Uneven closing force: Additional latch points or changed positioning; testing with specified preload.
• Unclean sealing faces: Deburring, polishing, protection against particles; visual in-process inspection.
• Migration or aging effects: Suitable sealing materials, resistance evidence, replacement intervals.
• Leak paths at add-on components: Sealing washers, O-rings, membranes; structural separation of sealing and fastening areas.
• Miscalibrated test rig: Regular calibration, reference leak testing, environmental compensation.

Integration of Branding Without Compromising Sealing

Branding can be applied as print, embossing or an applied emblem. It is important that no sealing lines are drilled through or loaded. If fixing points are needed, sealing concepts—such as sealing washers or molded-in bosses—are provided by design and included in testing. Solvents from paints and adhesives should be compatible with sealing materials; aging tests ensure long-term stability.

Sustainability and Service Life of Seals

Seals are wear parts. Replaceable profiles extend the service life of cases and transport containers. Material selection (e.g., EPDM or silicone), care instructions, cleaning with suitable agents and storage away from UV and ozone sources increase service life. In a manufactory, spare seals, alternative profiles or membrane inserts can be provided on a project-specific basis without losing testability.

Practical Checklist for Seal Integrity Testing

1. Define requirements: protection rating, medium, temperature range, lifecycle.
2. Select test method: pressure decay, flow, vacuum chamber or tracer gas—matched to volume and accuracy.
3. Secure the design: sealing line, latches, hinges, feed-throughs, pressure equalization.
4. Design the test fixture: adapters, compression paths, stabilization times.
5. Set thresholds and cycle times: consider measurement uncertainty and environment.
6. Ensure calibration: reference leak, sensor check, regular maintenance.
7. Implement documentation: traceability, serial/lot reference, track changes.
8. Keep service life in view: seal replacement, care, visual inspections in service.