[ Vacuum Diagnostics · Helium Mass Spectrometer Testing ]
Helium Leak Testing
& Vacuum Leak Detection
YTI provides helium mass spectrometer leak testing for vacuum coating systems, chambers, pumps, feedthroughs, valves, welded assemblies, vacuum piping and individual components. Testing can be performed on-site nationwide or at YTI to identify leaks that prevent equipment from reaching and maintaining reliable vacuum.
Vacuum Integrity Testing
Find the leak before replacing the system
A vacuum system that will not reach its normal base pressure does not automatically need a new pump. The problem may be a failed seal, damaged O-ring, leaking feedthrough, cracked weld, valve fault, loose flange or another path allowing atmosphere into the vacuum boundary.
Helium mass spectrometer leak testing provides a controlled method for locating these leak paths. Helium is introduced around or within the test object while a leak detector monitors for the tracer gas. A measurable helium response helps identify where gas is entering or escaping the system.
YTI combines leak detection equipment with decades of experience troubleshooting complete vacuum coating systems. That allows the technician to evaluate the helium response alongside the chamber, pumps, gauges, valves, controls, feedthroughs and connected process equipment.
Leak Testing Capabilities
Test the complete vacuum boundary or isolate individual components
YTI can evaluate complete installed vacuum systems as well as removable pumps, feedthroughs, fabricated assemblies and individual components. The correct approach depends on the equipment, accessibility, operating pressure and suspected failure.
Chamber Leak Testing
Test coating chambers, bell jars, load locks, doors, viewports, ports, chamber penetrations and other vacuum-boundary surfaces.
Feedthrough & Flange Testing
Evaluate electrical, high-voltage, fluid, motion and sensor feedthroughs along with flanges, adapters, fittings and seals.
Welded Assembly Testing
Verify vacuum integrity after chamber modification, welding, brazing, fabrication, piping changes or component repair.
Vacuum Line & Valve Testing
Diagnose leaks through valve bodies, shaft seals, fittings, tubing, flexible connections and vacuum distribution hardware.
Pump & Foreline Leak Checks
Evaluate diffusion pump assemblies, mechanical pumping systems, forelines, isolation valves, traps and connected vacuum hardware.
Individual Component Testing
Controlled testing for repaired components, custom vacuum assemblies, replacement hardware and parts before installation.
Common Warning Signs
When should a vacuum system be leak tested?
Changes in pump-down time, base pressure or process repeatability can indicate a leak, especially after maintenance, equipment relocation, seal replacement or fabrication work.
Slow Pump-Down
The chamber takes significantly longer than normal to reach its process pressure.
Poor Base Pressure
The system stabilizes above the vacuum level normally achieved under the same process conditions.
Pressure Rise
Pressure increases unexpectedly after the chamber or a section of the system is isolated.
Recent Maintenance
Flanges, seals, valves, feedthroughs or pumps were disturbed and vacuum performance changed afterward.
New Welding or Fabrication
A chamber, pipe, fitting or custom assembly was modified and its vacuum integrity needs to be verified.
System Relocation
Equipment was decommissioned, moved and recommissioned and needs verification before returning to production.
Unstable Process
Coating results or chamber behavior change from cycle to cycle without an obvious process cause.
Suspected Component Leak
A feedthrough, valve, seal, viewport or individual component is suspected but the leak location has not been confirmed.
Complete Vacuum Diagnosis
Poor vacuum does not automatically mean an atmospheric leak
A system can behave as though it has a leak even when the vacuum boundary is intact. YTI evaluates the overall condition of the system before assuming that helium testing alone will identify the problem.
Atmospheric Leak
Failed O-rings, loose flanges, cracked welds, leaking feedthroughs, valve faults and damaged chamber hardware.
Virtual Leak
Blind holes, threads, enclosed cavities and trapped volumes can slowly release gas and imitate an external leak.
Outgassing & Contamination
Water vapor, oil, process residue and contaminated chamber surfaces can keep pressure elevated without a physical opening.
Pumping Problem
Weak pumps, valve restrictions, diffusion pump problems, cryogenic faults or foreline issues can reduce vacuum performance.
Gauge or Sensor Problem
Contaminated gauges, failed sensors, incorrect ranges or control faults can report vacuum conditions incorrectly.
Process Conditions
Chamber loading, process gases, water cooling and cycle changes can affect observed vacuum without a chamber leak.
Helium Leak Detection Methods
The test method depends on the system and suspected leak path
Helium leak detection is not a single universal procedure. YTI selects the appropriate method based on whether the component can be evacuated, pressurized, isolated or tested as part of an assembled production system.
Outside-In Testing
The test object is evacuated while helium is applied around seals, joints, welds, feedthroughs and suspected leak locations. The detector identifies helium entering the vacuum boundary.
Inside-Out Testing
Helium is placed inside a component or assembly and the exterior is checked for tracer gas escaping through a leak path.
Sniffer Testing
A helium-sensitive probe is moved around the test object to identify tracer gas escaping from a pressurized component or assembly.
Accumulation Testing
Escaping helium is allowed to collect in a controlled enclosure before being sampled when direct probing is difficult.
Field & Facility Support
On-site leak testing or controlled testing at YTI
Large coating systems and production equipment are often best diagnosed in their installed configuration. Individual vacuum components and repaired assemblies may be better suited to controlled testing at YTI.
Field Leak Testing
Appropriate for complete coating systems, production chambers, pumping systems, equipment after maintenance, plant moves and faults that only appear when the full system is assembled.
View field service →Component Leak Testing
Appropriate for removable pumps, feedthroughs, valves, fabricated assemblies, repaired parts and vacuum components that can be isolated from the production system.
Request component testing →Complete Vacuum Diagnosis
Appropriate when it is unclear whether the problem comes from a leak, pump, gauge, valve, contamination issue, control fault or another part of the vacuum process.
View troubleshooting →The YTI Process
Diagnose, isolate, locate and verify
A useful leak test should produce an actionable result. YTI reviews the system history and operating symptoms before testing so the investigation is focused on the most likely failure paths.
Review the Symptoms
Review base pressure, pump-down time, recent service, process changes, system history and known problem areas.
Prepare & Isolate
Configure the chamber or component and isolate sections where practical to narrow the potential leak area.
Apply Helium & Test
Apply or sample helium using the appropriate method while monitoring the leak detector response.
Locate the Leak
Test seals, joints, welds, valves, feedthroughs and other suspected areas to isolate the actual leak path.
Repair the Cause
YTI can support seal replacement, component repair, welding, fabrication, pump service or related corrective work.
Retest & Verify
Repeat testing after repair and verify that the vacuum system can return to acceptable operating performance.
Vacuum Applications
Leak testing for production and research vacuum systems
Why Choose YTI
Leak detection connected to the complete vacuum process
Vacuum Experience
YTI has supported vacuum coating and high-vacuum equipment since 1984.
System-Level Diagnosis
Leak testing can be evaluated alongside pumps, gauges, controls, valves, cryogenic equipment and process conditions.
Repair Capability
YTI can support machining, welding, fabrication, pump repair, electronics, controls and component refurbishment after the fault is found.
Field & Depot Support
Installed production systems can be diagnosed on-site while removable equipment can be serviced and tested at YTI.
Frequently Asked Questions
Helium leak testing FAQs
What is helium leak testing?
Helium leak testing uses helium as a tracer gas and a mass spectrometer leak detector to locate gas passing through a vacuum boundary. Depending on the equipment, helium can be applied around an evacuated system or introduced into a pressurized test component.
Why is helium used to find vacuum leaks?
Helium can pass through very small leak paths and can be selectively measured by a helium mass spectrometer. That makes it useful for finding leaks that may not be visible or obvious from pressure readings alone.
What equipment can YTI helium leak test?
YTI can support vacuum coating systems, chambers, pumps, feedthroughs, valves, flanges, welded assemblies, vacuum plumbing, fabricated parts and other high-vacuum components depending on the equipment and required test configuration.
Can YTI perform helium leak testing on-site?
Yes. On-site helium leak detection can be performed as part of vacuum troubleshooting, preventive maintenance, system relocation, recommissioning and other field-service work.
Can individual vacuum components be tested?
Yes. Pumps, valves, feedthroughs, welded assemblies and other removable vacuum components may be tested individually when the component and required setup allow it.
Does poor base pressure always mean there is a leak?
No. Poor base pressure can also be caused by contamination, outgassing, trapped volumes, worn pumps, valve restrictions, gauge errors, cryogenic problems or other equipment faults. YTI can evaluate the complete vacuum system before determining the correct repair path.
Should a chamber be leak tested after welding?
Leak verification can be appropriate after chamber welding, flange modification, feedthrough replacement, fabrication or other work that changes the vacuum boundary.
Should a coating system be leak tested after relocation?
Yes, leak checking can be an important part of recommissioning. Moving a system can disturb flanges, O-rings, feedthroughs, valves, vacuum plumbing and other connections that should be verified before process validation.
Need to locate a vacuum leak?
Send YTI the system manufacturer, model, current base pressure, normal operating pressure, recent maintenance history and what changed. Our team can help determine the correct diagnostic path.
