Hermetic Fiber Feedthroughs Versus IP68 and Leak-Rate Evidence

Direct answer

IP protection, gas leak rate and optical loss address different properties. For fiber feedthrough procurement, define the wall, seals and fiber boundary, specify gas, pressure differential, temperature and leak criteria, and review optical channels separately. Neither an IP68 label nor a helium-test pass qualifies the complete system by itself.

Draw gas and optical boundaries separately

The IEC 60529 scope concerns enclosure protection. Douglas's fiber-feedthrough information identifies dedicated sealing construction and helium testing alongside optical checks. One unexplained pass label cannot replace those different records.

Use this guide for OEM sealed-enclosure and instrument reviews. It supplies no vacuum, pressure-equipment or explosion-protection design procedure, and asserts no ARRANEX hermetic or vacuum-qualified offering.

Record	Question	Unsupported inference
IP report	Which enclosure/state was evaluated?	Gas leak rate is established
Helium record	Which boundary and conditions?	Every gas/temperature behaves identically
Vacuum pressure	What pressure did the system reach?	That number is feedthrough leak rate
Optical report	Which channels and connection boundary?	Sealing passed

Define every interface through the wall

Identify the housing-to-wall joint, fiber seal and terminations/retention on both sides. Where evidence covers only the feedthrough body, the system party must still review its mounting interface.

Retain specimen fiber count, construction revision and materials. Matching flange shapes do not establish identical internal seals. Changes to fiber, coating or exit design need an applicability review of prior evidence.

Keep conditions with leak-rate units

Pfeiffer's leak-rate explanation relates gas flow to pressure, volume and time and discusses gas, temperature and pressure conditions. mbar describes pressure; mbar·L/s expresses leak rate. Comparing only exponents is invalid.

Retain original units, gas and pressures on both sides for the test party to compare. Ask for the reference basis of an unexplained cc/s value rather than assuming a conversion or acceptance. This guide sets no universal hermetic limit.

Review optical evidence separately

List channel identification, agreed wavelength-specific optical tests and sealing validation separately, referring each to the same specimen revision.

Record connectors, protection or mounting added after sealing. Original feedthrough evidence does not automatically cover subsequent assembly changes. Material outgassing data also cannot replace a leak-rate result.

Deliverable	Retain	Review
Seal drawing	Wall, body, fiber and ends	Tested interface
Service conditions	Gas, temperature, pressure direction/range	Approved requirements
Leak report	Method, units, conditions, detection capability	Comparable result/criteria
Optical record	Fiber IDs, wavelengths, connection boundary	Matching signal path
Change/installation record	Material, termination and retention changes	Validation requiring review

Procurement FAQ

Does IP68 mean hermetic? Obtain gas-leak evidence for the specified boundary.
Does a helium pass cover every service gas? Have the responsible party establish applicability.
Can vacuum pressure be the leak-rate limit? Their dimensions and meanings differ.
Does not detected mean absolutely zero leakage? Retain method, detection capability and acceptance conditions instead of making an absolute claim.
What belongs in the RFQ? Seal/optical drawings, service boundary, required evidence and responsibility for approving the test plan.

Sources and review date

Reviewed on 2026-10-18. Source dates remain separate from the review date. Manufacturer examples explain terminology only; procurement tables are editorial recommendations, not ARRANEX specifications or certifications.

Sources checked: 2026-10-18