Mecadi laboratory service
Determining the gas permeability of plastics is a decisive factor in the selection and development of materials. We offer you various methods for determining permeation – including measurement using so-called manometry (also known as “pressure rise measurement”).
This measurement method is based on the ISO 15105 or CSA/ANSI CHMC 2:19 test standards. In addition to the standard conditions, we offer a wide pressure and temperature range for individualized testing.
In essence, the method describes a procedure for determining the gas permeability through flat plastics such as films, film webs, laminates, co-extruded or coated materials with the aid of a partial pressure difference.
The test cell required for this consists of two chambers that are separated by the sample to be tested (e.g. film/plate) (see schematic diagram below). One chamber is filled with the test gas, e.g. hydrogen (so-called feed side), while the opposite chamber is evacuated. The permeation of the gas through the material leads to an increase in pressure in the initially evacuated chamber. The permeation rate of the material is calculated from the pressure increase rate.
Schematic representation of the measurement setup for determining permeation using manometry.
The advantages of our service
- Precise measurement results: We offer you accurate measurements of permeation rate/coefficient and diffusion coefficient based on recognized standards such as ISO 15105 or CSA/ANSI CHMC 2:19.
- Flexibility in test conditions: We offer a wide range of test conditions, including variable temperatures (-50 °C to +150 °C) and pressures (up to 1000 bar) to meet the specific requirements of your project.
- Advanced tests: In addition to the standard measurement of permeability, we also offer more advanced tests, such as the determination of diffusion coefficients, gas solubilities (sorption and desorption).
- Individual advice: Our team is on hand to advise you on the best test methods for your specific materials and requirements.
Detection limits and recommendations
The manometric permeation measurement offers a high sensitivity and enables the determination of permeation rates from 50 cm3 m-2 day-1. A reduction in test time and test costs can be realized, as far as possible, by using thinner materials and increasing the test temperature.
Requirements for your samples
- For a precise measurement, we need your samples in a format that meets the standard requirements (circular cut-outs with a diameter of at least 100 mm, or DIN A4 sheets). For standard measurement, we require samples with a diameter / edge length of at least 90 mm.
- It is important that the sample is representative of the material and has no faults or defects.
- Thickness variation < 5%, roughness r(a) < 20 μm.
- We are happy to determine the thickness of the sample for you in accordance with ISO 4593.
- We realize sample cutting from larger containers by cutting, punching, laser cutting, water jet cutting (external).
- For tissue-containing samples, we offer additional cut-edge masking to prevent false-to-low false results.
- We recommend sending at least three independent samples per test. We usually measure samples with a thickness of 20 µm to 3 mm. Other thicknesses are also possible on request.
Test media
We offer a wide range of different test gases and liquids in order to be able to react flexibly to your request. These include, for example
Standard: hydrogen, nitrogen, oxygen, helium, argon, krypton, etc.
Specialties: NH3, H2S, Cl2, HCl, SF6, NO, NO2, short-chain alkanes, etc.
Result units
- Permeability per unit area (permeation rate): cm3 m-2 day-1 bar-1
- Additional standardization to sample thickness (permeation coefficient: cm3 mm m-2 day-1 bar-1
- Specification cm3 in standard state according to DIN 1343: Gas volume at 273.15 K (0 °C) and 1.01325 bar (1 atm).
Test conditions
- For material use in a specific application, the permeation data should be selected as close as possible to the operating point of the application (pressure, temperature). For material characterization (comparison with existing / competitor materials), the test conditions of the standard should be used (pressure, temperature).
- According to ISO 15105: 23 ± 2 °C at 1 atm partial pressure difference
- Possible test temperatures at Mecadi
- -10 to +100 °C (standard)
- -50 to +150 °C (extended range)
- Others on request, subject to technical feasibility.
- Temperature profiles (non-isothermal measurements), e.g. CARB cycle
- Test pressures possible with Mecadi
- 0 to 10 bar, absolute (standard)
- 0 to 100 bar, absolute (extended range)
- 0 to 1000 bar, absolute (on request)
Get in touch with us!
Would you like to find out more about our manometric permeation measurement or request a measurement for your materials? Our team will be happy to discuss all the details and help you with customized solutions. Contact us today to find out more about our services and discuss your specific requirements.
By the way: You can find a complete list of our test methods and services here: https://www.mecadi.com/de/permeationsmessungen/ (more on request)
