Why making use of an accredited laboratory?

Outsourcing metrology to a calibration laboratory is the guarantee of obtaining, under accreditation, a calibration certificate or an indisputable verification statement that is binding on a third party (auditor, authority, customer), with complete impartiality.
The traceability of the calibration results to the International System of Units (SI) and the technical competence of the calibration laboratory are audited by the Cofrac's body every 12 to 18 months when the internal metrology services are audited only every 5 years.
ETALONAIR offers the largest accredited field in Europe for reference concentrations obtained by dynamic dilution in order to achieve binary and ternary mixtures of CO, CO₂, O₂, NO, NO₂, SO₂, N₂O, NH₃, C₃H₈, CH₄ et C₂H₆.
The choice of dynamic dilution by mass flow regulators provides a high degree of dosing flexibility to meet all demands and monitor the evolution of the test concentrations required by the standards.
ETALONAIR is a calibration laboratory accredited by the Cofrac's body under no. 2-5904 in the field of Chemistry & Reference Materials – Gas Analyzers, available at

2 - What is the difference between a calibration and an adjustment?

A calibration is the measurement of the deviation between the instrument indication and the reference concentration applied to its inlet.
To avoid possible cross sensitivity, calibrations are performed for only one compound at a time.
An adjustment is a tuning of the instrument to minimize deviations, assumed the response is linear.
ETALONAIR always performs an adjustment of the instrument before calibration, unless otherwise instructed by the customer or physically impossible.
In this case, the instrument is calibrated as is.
When an adjustment is made, the indications before and after adjustment are included in the results report.

3 - What are the proposed calibration works?

Continuous signal analysers using standard reference methods or alternative methods, gas detectors are the calibration objects.
The measurand is a reference concentration expressed in International System Units (SI) in mol.mol-¹ or g.m-³.
Each measurement result is associated with measurement uncertainty (see ISO 17025:2017 § whose main components are the standard uncertainties on the reference(s) and the influence of the calibrated instrument on the measurement (bias).
This measurement uncertainty is taken into account in declarations of conformity, where appropriate.
ETALONAIR uses standard methods mentioned in its scope as well as internal methods to supplement inaccuracies.
Lack to fit, repeatability, limit of quantification (LQ), response time are determined according to the method described in the general EEC standards NF EN 15267-3 (2008) or NF EN 15267-4 (2017).
The response factor to an organic compound (FID analyzers) is determined by the methods described in the General Standards or ISO 25140 (2010).
The cathalyst efficiency rate is determined by the method described in ISO 25140 (CH₄) with ethane.
The efficiency of a NOx/NO converter furnace is determined according to method C2 described in EEC standard NF EN 14792 (2017).
The cross sensitivity rate is determined at zero and span using an accredited internal method.
The influence of oxygen is determined according to the methods described in the EEC general standards or in the EEC standard NF EN 12619, or ISO 25140.
ETALONAIR, listening to its customers, is constantly innovating to offer more and more calibration solutions.

4 - How accurate is the calibration?

The measurement uncertainty and associated confidence interval must be consistent with the type of measurement being performed.
If the given measurement result is 1642 ±34.10-⁶ mol.mol-¹ at 2 SD, this means that the combined uncertainty of 17.10-⁶ mol.mol-¹ has been multiplied by a coverage factor equal to 2 for a 95.45% level of confidence.
The actual value of the measurement has a 95.45% chance of being in the range [1608.10-⁶ mol.mol-¹ - 1676.10-⁶ mol.mol-¹].
Writing 1642,452.10-⁶ mol.mol-¹ would make no sense here given the value of expanded uncertainty.
The expanded uncertainty is always expressed as 2 significant figures rounded by excess, with the associated result aligned on it.
For each line of its scope of accreditation, the laboratory specifies the best absolute uncertainty for a given range of concentrations.
ETALONAIR calculates its combined uncertainties by looking at all the independent components that contribute to it using the 5-M method, then calculating a quadratic mean (AKA the law of distribution of uncertainties).
ETALONAIR primarily uses Type B uncertainty calculations (based on the GUM) to assess the contribution of each component to the final composed uncertainty.

5 - What report on the results is provided?

A results report is used to establish confidence in a measurement instrument and to link the results to the International System of Units (SI).
There are 3 types of reports:
- A calibration certificate giving the linearity deviations ;
- A verification statement based on the results to determine the conformity of the instrument to your specifications (specified requirements) according to :

- Criteria in Table 1 of the specified standard ;

- Manufacturer’s criteria ;

- Specific criteria related to a process ;

- A test report.

The results under accreditation shall be indicated by the symbol (A).
Conformities based on results under accreditation are also subject to accreditation.
When a report contains at least one result under accreditation, it bears the Cofrac's logo on the cover page.
ETALONAIR specifies in its estimates which kind of report will be issued after a review of request.
ETALONAIR can assist you free of charge to define the needs and comply with the regulations in force.

6 - Which periodicity of calibrations ?

The calibration laboratory does not indicate any recommendation regarding the periodicity of calibration (see ISO 17025:2017 §, unless agreed in written with the customer.
For each instrument, a calibration interval must be defined according to its frequency of use and its tracking sheet.
The Opperet method is not recommended because of many discontinuities introduced by maintenance and necessary adjustments on a gas analyzer, throughout its lifetime.
Good operating practices, in particular through proper gas conditioning prior to analysis, make it possible to significantly reduce curative maintenance actions.
ETALONAIR recommends calibrating after curative maintenance when an organ of influence on the result is replaced (light source, optical element, converter load, signal processing board) or when a physicochemical characteristic has been modified (flow rate, pressure or sample temperature in the measuring tank).

7 - How do I get a quote ?

A work request form can be downloaded from this site.
A specification is mandatory to obtain a verification statement.
As a minimum, provide the following information :
- The brand and model of the instrument ;
- The compounds measured and the scales to be calibrated ;
- The analysis flow rate ;
- A possible mention requesting not to adjust the instrument ;
- Contact details of the company and the full name of the applicant ;
- A desired planned date.
ETALONAIR undertakes to respond within 24 hours to sufficiently informed or recurring requests.
ETALONAIR strives to meet the requested dates within to the extent of the work already planned.
The proposed dates in the estimate are firm and final only upon receipt of a valid order.

8 - What commits me by placing an order ?

The purchase order allows to book the planned date in the estimate.
For a first order, you will have to fill out a customer account form, downloadable from this site.
To be validated, a purchase order must stipulate :
- the estimate number with its revision (doing this way, no need to copy the estimate) ;
- An order number ;
- The legal name of the entity to be invoiced and the VAT number ;
- The delivery address to send the instrument back ;
- A notice whether the instrument will be removed on our premises ;
- The billing address or an email where to send the invoice ;
- The entity on whose behalf the report is to be prepared, where applicable.
ETALONAIR accepts the cancellation of an order free of charge 15 calendar days before the start of the work.
ETALONAIR tolerates an "End user agreement" in order to shorten an administrative delay but the instrument, after work, will be returned only upon receipt of a valid order.

9 - When and how to send my instrument?

ETALONAIR must always carry out a request review that guarantees the adequacy of the skills and availability of the laboratory resources at your request.
Without this step, no instrument will be able to receive an adequate work.
The instrument must be received on our premises no later than the date specified in the estimate to comply with the current planning, including the maintenance time.
The instrument must be effectively protected against mechanical shock during transport or handling by careful and appropriate packaging.
Attach the necessary accessories for calibration :
- EEC mains cord ;
- Analog output cord ;
- Special pneumatic fittings other than SWAGELOK® or similar ;
- Converter furnace, external pumps assigned to the instrument ;
- External power device or new batteries ;
- Digital link cable (with communication protocol and IP addresses) ;
- Calibration accessories ;
- Instructions for use or quick start instructions (in French or English) ;
- Proprietary software for data collection (networked detectors).
When a software is subject to a license, the supply and the right of use must be transferred to the laboratory, the time to carry out the work.
The purchase of priced licences, the remote control and on-line assistance over a surtaxed phone number are not accepted.
ETALONAIR always uninstalls any software provided after use and retains no copy, unless the license owner agrees in writing.
ETALONAIR lists and returns all items attached to the shipment.

10 – Can reports be received in paperless form ?

ETALONAIR offers reports in PDF text format allowing selection, authenticated and signed by RGS* digital key, provided that the requirements of the ISO 17025:2017 standard are met.
On request, an original signed in paper form is mailed in followed letter.
Only one original is issued, either in paper or paperless form.
ETALONAIR shall provide free of charge a duplicate, with the same probative value as the original, in the event of its loss or destruction.

11 - Can the calibration be performed on site ?

ETALONAIR performs all calibrations under accreditation in its fixed installations.
In case of need for on-site work, we can perform out-of-accreditation calibrations.


Call us at :

numéro de téléphone +33 967 124 329 or +33 442 104 329

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