Crowcon's Gasman Diving H2S personal gas detector is protecting divers in the North Sea by monitoring hydrogen sulphide (H2S) gas in diving bells.

The diving industry has long been aware of the danger of H2S on subsea worksites and the danger of it getting into the diving bell. The severity of the problem varies worldwide and is particularly bad in waters, which have effectively been used as 'chemical dumps'.

When approached by a major North Sea oil producer, concerned about divers working on sites with elevated H2?S levels, Unimed Scientific Limited (USL) considered Crowcon's Gasman portable gas detector as a possible solution. USL is a leading provider of scientific back-up and guidance to the North Sea diving industry. The company is also a leading auditor of dive systems.

Dr Valerie Flook, together with Crowcon, put the Gasman Diving through a range of tests to prove its suitability for use in diving bells. Initial tests subjected the device to high pressures of up to 20 bar, while exposing it to known concentrations of H2S to test its accuracy. USL also evaluated the hysteresis (the response to a rising signal differs from that to a falling signal) of the response at these gas levels and pressures. In addition, tests were carried out to ensure there was no risk of the detector being damaged by rapid pressure changes.

Following this testing, a few minor changes were made to ensure the Gasman Diving was fully fit for purpose. These included a small hole being placed in the back of the instrument to allow for rapid equilibration of pressure changes, with the addition of a small Gore-Tex membrane to protect the internal components of the detector from water ingress.

The Gasman Diving is now in use with several of the leading diving companies in the North Sea and is available worldwide.

It is a reliable and robust detector that provides accurate gas readings, even under high pressures, which can be easily downloaded and stored. Its small size and easy to read display makes it especially suitable for the confined spaces of the diving bells. Initial feedback from divers has also been positive.

Crowcon, a subsidiary of Halma p.l.c., is a world leader in portable and fixed gas detection instruments.

Crowcon's distributor in India: Detection Instruments Pvt Ltd, Navi Mumbai. Tel: 022-27617663-66. Fax: 91-22-27612103. Email: general@detection-india.com, sales@detection-india.com