What Is Outgassing?
The outgassing test is a test in which the volatile substances a material releases under high vacuum and elevated temperature are measured as total mass loss (TML) and collected volatile condensable material (CVCM).
Purpose of Outgassing
The purpose is to verify that a material intended for use on a spacecraft does not contaminate optical surfaces and sensitive components.
Which Products Is Outgassing Applied To?
- Adhesives and filler materials
- Cable insulation and coatings
- Polymer structural elements
- Thermal-control materials
In Which Sectors Is Outgassing Used?
Standards Related to Outgassing
- ASTM E595
- ECSS-Q-ST-70-02
- NASA-STD-6016
Outgassing Conditions
- Vacuum
- High vacuum level defined in the standard
- Temperature
- 125 °C in ASTM E595
- Time
- 24 hours
- Quantities measured
- TML (total mass loss) and CVCM (collected volatile condensable material)
Equipment for Outgassing
- High-vacuum system
- Heated specimen chamber and collector plate
- Microbalance
- Temperature control system
Sample Requirements for Outgassing
- Specimen mass must be prepared per the standard
- It must be conditioned in the defined environment before the test
- Initial mass must be measured on a microbalance
- The number of specimens is defined in the standard
Duration of Outgassing
24 hours in vacuum; together with conditioning and weighings, a few days.
Outgassing Procedure
- 1The specimen is conditioned and its mass is measured.
- 2The specimen is placed in the vacuum chamber.
- 3The system is pumped down to the defined vacuum.
- 4It is held at 125 °C for 24 hours.
- 5The specimen and the collector plate are weighed.
- 6TML and CVCM are calculated.
Outgassing Acceptance Criteria
The acceptance criterion is given in space specifications; the common criterion is that TML does not exceed 1% and CVCM does not exceed 0.1%.
Evaluation of Results
High CVCM leads to contamination of optical surfaces. The two values are evaluated together in material selection.
Outgassing Report
- Standard applied
- Vacuum level, temperature and duration
- Initial and final masses
- TML and CVCM values
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- Space material specifications (ECSS, NASA)
Aerospace Testing — What Does This Testing Field Cover?
The section below describes the field that the Outgassing test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Aerospace testing shows that equipment keeps working in the flight environment and provides evidence for the airworthiness file. In this family the acceptable probability of failure is several orders of magnitude lower than in other sectors; this directly determines the scope of testing and the certification burden.
The most distinctive feature of the field is TRACEABILITY. Which melt an aircraft part came from, in which heat treatment furnace and with which cycle it was processed, which operator made the weld and which inspector approved it are all recorded. The test report is one link in this chain; if the chain is broken, the report carries no value on its own.
Environmental qualification runs through RTCA DO-160, with categories selected according to the equipment's MOUNTING LOCATION in the aircraft. A device mounted on the cockpit panel and one mounted inside the wing pass the same section under different categories. When reading a DO-160 report it is therefore essential to know which sections were applied at which categories.
On the software and complex hardware side the approach changes entirely: the evidence is not testing but PROCESS ASSURANCE. DO-178C for software and DO-254 for complex electronic hardware define how the development process is to be run and which evidence is to be produced. Every step, from requirement to code, from testing of the code to coverage analysis, must be traceable. Testing software does not make it certifiable; the process record does.
A separate body of work applies on the material and special process side. AWS D17.1 is used for welding, SAE AMS 2750 for pyrometry in heat treatment and NAS 410 for non-destructive testing personnel. For special processes (heat treatment, coating, welding, NDT, bonding) NADCAP accreditation is effectively mandatory in the supply chain; without NADCAP it is not possible to sell parts to many OEMs.
On the quality system side the AS/EN 9100 series is used: 9100 for manufacturers, 9110 for maintenance organisations and 9120 for distributors. Without these certificates it is practically impossible to enter the aerospace supply chain, and audits are markedly more detailed than in other sectors.
Counterfeit part risk is a subject peculiar to the field. Separate standards and verification methods (visual inspection, X-ray, decapsulation and internal structure examination, XRF) are used to detect counterfeit or reworked parts in the electronic component supply chain.
Space applications add further layers: outgassing in vacuum, radiation tolerance, long-duration thermal vacuum cycling and assessment of single event effects.
Method groups in this field
Environmental qualification
RTCA DO-160 sections: temperature and altitude, vibration, shock, humidity, sand and dust, fungus, salt fog, fluid susceptibility, icing, lightning.
Electromagnetic
The EMC sections of DO-160; MIL-STD-461 and MIL-STD-704 power characteristics on military platforms.
Software and hardware assurance
DO-178C software life cycle and DO-254 hardware design assurance evidence; requirement traceability and coverage analysis.
Materials and welding
Welding qualification under AWS D17.1, mechanical testing of materials, metallography and non-destructive examination.
Special process control
SAE AMS 2750 pyrometry, coating and heat treatment process verification, preparation for NADCAP audits.
Space environment
Thermal vacuum cycling, outgassing, radiation tolerance and acoustic/vibration qualification.
Commonly confused in this field
- There is no such document as a "DO-160 certificate"; DO-160 is a test specification and its output is a qualification report.
- The selection of sections and categories comes from the customer's equipment specification; the laboratory cannot make that selection on its own.
- DO-178C and DO-254 cannot be satisfied by testing; the evidence is the traceability of the development process.
- An AS9100 certificate is not a product approval; it is a quality system certificate and part approval runs separately.
- For special processes, work carried out without NADCAP is not accepted in the supply chain even when it is technically correct.
- MIL-STD-810 and DO-160 are often confused: one is a military and the other a civil aviation specification, and their profiles differ.
Which decisions these results support
- Airworthiness and TSO/ETSO files
- Entry into the aerospace supply chain and supplier approval
- Special process approval and NADCAP preparation
- Determining the impact of a design change on qualification
- Managing counterfeit part risk and component verification
Related Tests
Frequently Asked Questions About Outgassing
What do TML and CVCM mean?
TML is the percentage of total mass the material loses. CVCM is the portion of this loss that condenses on cold surfaces, and is the value critical for optical contamination.