New International Working Group Focuses on Hydrogen-Specific
Detectors
Karen Hall, National Hydrogen Association
ISO TC 197 has formed a new Working Group (WG 13: HYDROGEN DETECTORS) to focus
on the development of an international standard for hydrogen-specific detectors.
The group held their inaugural meeting on 23 & 24 January in Tokyo, convened
by Dr. Ichiro Matsubara. Representatives from Japan, Korea, USA, and France were
present.
 The
background for the formation of WG13 was presented by Convener Matsubara. He explained
that in May 2005, an ad hoc group meeting in Washington DC identified that there
is currently no international standard for hydrogen-specific sensors. Japan has
recently undergone deregulation to enable broad use of hydrogen, including the
deployment of hydrogen refueling stations. This deregulation was made possible
by securing safety concerns. One common fundamental safety element is monitoring
for hydrogen leaks. For ease and simplification of the regulation, it is desirable
to detect hydrogen selectively, rather than simply as one of the flammable gases,
such as exhaust gases.
IEC 61779, which covers requirements for flammable
gas detection, contains requirements that are an integral part of the activity
of WG 13, which is ISO Working Draft (WD) 24162. The requirements of control systems
as well as installation requirements are excluded from the draft standard being
prepared by WG13. Only performance requirements and test methods for hydrogen-specific
detectors will be covered.
While IEC 61779 covers detectors for flammable
gases, there are no provisions for measuring range, selectivity and poisoning,
which are considered essential for securing the safety of hydrogen installations.
Likewise, UL 2075 covers toxic and combustible gas and vapor detectors and sensors
intended to be portable or employed in indoor or outdoor locations in accordance
with the National Electrical Code, NFPA 70.
IEC 61779 is currently maintained
by IEC TC 31, and parts 1 and 6 are being incorporated into IEC 60079 - 29 (-1
and -2, respectively). Parts 2-5 have been repealed. IEC 60079 - 29 -1 and IEC
60079 - 29 - 2 have not yet been published. Therefore, WG13 has taken all of the
appropriate requirements from IEC 61779 as a baseline for WD 26142. Some requirements
have been modified for hydrogen-specific detection.
The ISO WD took as
many provisions from the IEC standard as possible. However, WG13 recognizes that
IEC 61779 does not address some issues that should be addressed for hydrogen-specific
detectors.
 Due
to hydrogen's wide flammability range, it is desirable to detect lower concentrations
with more accuracy than afforded in IEC 61779. WD 24162 proposes a slight modification
of the calibration curve and accuracy range allowed in IEC 61779 in order to make
them more appropriate to the parts per million (ppm) range desired for detection
of hydrogen concentration. Response time, short-term stability, long-term stability,
recovery time and poisoning will all be addressed, utilizing the requirements
of IEC 61779 where applicable.
The existing IEC standard suggests a very
sophisticated test chamber due to the wide variety of gases that are to be detected.
The new ISO WD proposes a simpler test chamber that addresses the issues of hydrogen
detection only.
The Working Group is now attempting to create a standard
similar to standards accepted for flammable gas detection devices, but modified
for the unique needs of a stationary hydrogen facility. They are also working
to simplify any tests where doing so does not compromise the intent, but merely
avoids steps and equipment that are designed to test detection equipment for gases
other than hydrogen.
Anyone interested in applying to join WG13 is encouraged
to contact the Administrator of their National Technical Advisory Group (TAG).
In the US, contact Debbie Angerman at CGA.
|
