The Vuototecnica ATS series is an electrically powered welding control system that uses the vacuum bell method for non‑destructive testing of weld and seal integrity in food‑grade cellophane, PVC, and other flexible packages. Rather than relying on subjective manual inspection, the ATS creates a controlled negative‑pressure environment inside a transparent PMMA bell jar. The test object—a freshly sealed package—is placed on the sealed support surface, the bell jar is lowered, and a dry rotary vane vacuum pump evacuates the chamber. As the internal vacuum increases, the pressure differential between the trapped air inside the package and the evacuated chamber causes the package to expand. Any leak in the weld or seal allows air to escape, visible as bubbling, package collapse, or failure to expand—providing immediate visual evidence of seal failure.

How the Vacuum Bell Method Works

• Controlled Negative‑Pressure Environment: The package is placed on a flat, sealed support surface. The transparent organic glass (PMMA) bell jar is lowered over the sample, and a dry rotary vane vacuum pump evacuates the chamber. As the vacuum level rises inside the bell jar, the atmospheric pressure trapped inside the sealed package exerts an outward force on the package walls and, critically, on every weld seam. The higher the vacuum inside the bell jar, the greater the mechanical stress placed on the seals—directly testing their strength under simulated transport and altitude conditions.
• Immediate Visual Leak Detection: Because the bell jar is transparent, the operator can directly observe the package's behavior under vacuum. A properly sealed package expands uniformly and remains inflated throughout the test cycle. A package with a weld defect will either fail to inflate, expand unevenly, visibly leak air bubbles (in wet‑sample testing), or collapse when the vacuum is released—providing instant, operator‑independent pass/fail determination without requiring complex instrumentation or interpretation skills.
• Weld Stress Proportional to Vacuum Level: The force applied to the weld seams is directly proportional to the vacuum level inside the bell jar. This allows the operator to select a test vacuum level that corresponds to the expected mechanical or environmental stresses the package will encounter during distribution—whether atmospheric pressure changes during air freight, compression during stacking, or internal pressure from packaged food outgassing.

Precise and Repeatable Test Cycle with Digital Vacuum Switch

• Digital Vacuum Switch for Setpoint Control: The ATS series integrates a digital vacuum switch housed in a protective enclosure. This allows the operator to program a specific vacuum setpoint (e.g., -0.6 bar) rather than manually monitoring an analog gauge and guessing when to stop the pump. The digital switch automatically controls the vacuum pump—starting, stopping, and maintaining the desired vacuum level—ensuring that every test cycle applies identical mechanical stress to every package, eliminating operator‑to‑operator variability.
• Two Manual Shut‑Off Valves for Cycle Management: Two bidirectional manual valves control the vacuum circuit: one isolates the pump from the bell jar, and the other vents the bell jar to atmosphere at the end of the test cycle. This simple, robust pneumatic design minimizes components that could fail or require calibration, while providing the operator with positive control over the test sequence—evacuation, hold at test vacuum, and venting.
• Repeatable Test Values: Because the digital vacuum switch ensures identical test pressures cycle after cycle, and the two‑valve circuit provides consistent evacuation and venting, test results are directly comparable between production batches. This repeatability supports statistical process control (SPC) and trend analysis, allowing quality engineers to detect gradual degradation in sealing equipment performance before it results in field failures.
• Configurable Vacuum Levels by Pump Selection: The maximum vacuum level achievable inside the bell jar depends on the dry rotary vane pump selected at time of order. Different pump capacities allow the ATS to be matched to the specific test requirements of different package sizes, materials, and seal strength specifications. Custom versions can also be supplied according to customer requirements.

Applications

• Seal integrity testing of food‑grade cellophane and PVC packages for snacks, baked goods, and confectionery
• Weld permeability testing of flexible packaging used in modified atmosphere packaging (MAP) and vacuum‑packed products
• Quality control sampling on food packaging production lines for compliance with internal seal strength specifications
• Laboratory testing of new packaging materials and seal designs under controlled vacuum conditions