Certificate of PRM 1

The title contains the mixture type (reference material), the components and the matrix gas.

This section contains a description of the cylinder and the provided mixture. For primary reference gas mixtures, the result is the gravimetrically determined value, while for certified reference gas mixtures, the result is the analytically determined value. The cylinder number is identical to the number that is stamped into the wall of the cylinder, and this is the only connection between the certificate and the gas cylinder. The contents of the cylinder are mentioned, followed by the type of cylinder together with the volume and the gas pressure. Finally, the valve outlet type of the cylinder is specified.

Our primary reference gas mixtures are prepared gravimetrically in accordance with ISO 6142-1:2015. With this preparation method, we can offer mixtures with traceable values for the amount fraction of the requested component(s) together with their guaranteed stability and uncertainty. The method used for the verification of the mixture against VSL’s primary standards is also specified.

For certified reference gas mixtures, the method(s) used to attribute the result of the composition is mentioned.

The amount fraction of each component with its uncertainty is listed here or on a separate page. The section below gives a description of the stated measurement uncertainty. All contributing factors to the uncertainty, such as the purity of the raw materials, the weighing process and verification of the prepared mixture are combined into the standard uncertainty in accordance with GUM ‘Evaluation of measurement data – Guide to the Expression of Uncertainty in Measurement’. The measurement uncertainty is provided as an expanded uncertainty.

For NO₂ mixtures, an NOₓ value can be found in the results table. NO₂ undergoes a dimerization reaction with N₂O₄, which is in equilibrium. Therefore, NO₂ mixtures always contain a small fraction of N₂O₄. HNO₃ is a second impurity of which trace amounts are found in NO₂ mixtures. The reported NOₓ result consists of the results of these three components. Furthermore, for NO₂ mixtures in nitrogen, approximately 1000 µmol mol⁻¹ of oxygen is added in excess during preparation. This is mentioned in the ‘Commutibility’ and ‘Additional information’ sections on the certificate.

The results on this certificate are traceable to VSL Primary Standards. This means that the result is related (traceable) to VSL’s reference standards. More information is given on the final page. As stated in ISO 6142-1:2015, the metrological traceability of Class I calibration gas mixtures arises from correct determination of the masses added, conversion of the masses to the amounts of substance (taking into account the purity) and verification against independent measurement standards.

Our primary reference gas mixtures are prepared gravimetrically in accordance with ISO 6142-1:2015. With this preparation method, we can offer mixtures with traceable values for the amount fraction of the requested component(s) together with their guaranteed stability and uncertainty. The method used for the verification of the mixture against VSL’s primary standards is also specified.

For certified reference gas mixtures, the method(s) used to attribute the result of the composition is mentioned.

This section contains specific information on the intended use of the cylinder.

The expiry date is the date until when VSL can guarantee the result of the measurement. After this date, the result is no longer guaranteed. When the certificate is expired, contact our Sales department for advice on how to treat the gas mixture.

All certificates contain an electronic signature to ensure authenticity. The signature is an electronic seal on the document that prohibits making alterations. Any alteration breaks this seal and is shown in the document. More information about the electronic signature can be found here.