Expanded humidity measurement capabilities

Controlling humidity is critical for maintaining product quality in pharmaceutical manufacturing and many other high-value industries. The accuracy of humidity measurements can be assured where networks of accredited instrument calibration service providers are available, that are supported by national metrology institutes able to respond to rising expectations. However, in some of Europe’s emerging economies, these institutes were unable to fully support local calibration service providers, holding back industrial development in these nations.


Monitoring and control of humidity are essential requirements
in a variety of Europe’s manufacturing industries. For example,
humidity affects pharmaceutical and biochemical product quality
and storage lifetimes.
Most humidity sensors are based on capacitance measurement
technologies that exhibit measurement drift, so regular calibrations
are needed to maintain service quality. National Metrology Institutes
(NMIs) maintain standards in this area, by providing fast, costeffective
calibration services to local calibration providers. These
calibrations can be delivered by measuring dew point and humidity,
using primary standards or via secondary devices or transfer
standard hygrometers. However, some European NMIs, with more
limited capabilities in humidity measurement, effectively limited
opportunities for local calibration service providers by requiring
calibrations to be sourced across national borders.
The National Metrology Institute for Ireland (NSAI), for example,
maintained national humidity standards but couldn’t provide
primary generation of dew points (a measure of moisture in the
air). Instead, traceability was outsourced to NMIs recognised by
the International Committee for Weights and Measures Mutual
Recognition Arrangement (CIPM MRA) and listed as having
appropriate Calibration Measurement Capabilities (CMCs).
NSAI also faced additional costs and delays from shipping precious
reference equipment, including chilled mirror hygrometers, overseas.
In turn, these limitations affected Ireland’s instrument supply and
laboratory service markets, stifling the potential for local providers to
serve profitable industrial sectors and adding overhead costs.


Supported by institutes with significant existing expertise —
specifically, INRIM (Italy), CMI (Czech Republic), TUBITAK (Turkey),
FSB (Croatia) and UL (Slovenia) — the EMPIR project Expansion of
European research capabilities in humidity measurement developed
relevant competences at institutes less experienced in research.
These were IMBiH (Bosnia and Herzegovina), MoE (Serbia), NSAI
(Ireland), ME-BoM (Macedonia) and MER (Montenegro).
FSB and INRIM led the development of a new type of chamber for
calibrating relative humidity instruments, that was characterised in
each partner country. New measurement procedures were devised,
and the chamber was used to determine the equivalence of
humidity measurement services at the participating laboratories.
Long-term strategies were implemented to support further research
and development; that included stakeholder workshops such as
that hosted by NSAI in Dublin in March 2019 attended by calibration
laboratories, pharmaceutical manufacturers, medical device
manufacturers, and electronics manufacturers.


The project allowed NSAI to build a dew point generator for primary
humidity measurements, traceable to the ITS-90 temperature
scale, enabling calibrations of chilled mirror hygrometers, reduced
costs and downtimes, and improved support to other chilled
mirror hygrometer users in Ireland.
The project also facilitated NSAI’s successful Calibration &
Measurement Capability (CMC) recognition for humidity
measurements, granted in 2019, as a Mutual Recognition
Arrangement approved calibration service provider.
NSAI then refocused on research and consultancy. This included
supporting Mason Technology, one of Ireland’s leading suppliers of scientific solutions to laboratories and industry, to attain ISO

17025 accreditation, as a competent humidity calibration laboratory.
For Mason Technology, becoming an accredited humidity calibration
provider enabled it to better serve the needs of its customers,
including in the high-value pharmaceutical and biochemicals
sectors, by offering more comprehensive instrument maintenance,
breakdown, calibration and certification services. Gaining the
capability to calibrate in-house also reduced its internal costs, since
it no longer needed to send instruments overseas for that purpose.
Scaled across participating NMIs, improved service provision and
research capabilities have provided Europe’s industries with access
to more responsive and efficient humidity measurement services.

Expanded research capabilities in humidity measurement

New measurement methods were devised and best practice shared among emerging NMIs to develop infrastructures for reliable, traceable humidity measurements across Europe supportive of each country’s key industries. The consortium designed an inner chamber to calibrate relative humidity (RH) instruments. The process of designing, producing and characterising the calibration sub-chamber indicated a significant reduction of temperature gradients and related measurement uncertainties. A characterisation protocol was prepared, and related measurements performed, plus knowledge gained from these investigations was shared among participating NMIs. All participants finished an inter-comparison measurement exercise using the new RH chamber that showed agreement and confirmed improved uncertainties. The results from this inter-comparison could support submissions of new or improved CMC claims to BIPM for publication in the Key Comparisons Data Base.

  • Category
  • EMPIR,
  • Industry,
Element 1 Element 2 Element 3 Element 1 Element 1 Element 1 Element 1 Element 1 Logo-Footer