Brick company chooses Opsis

Following a three-month trial, Hanson Brick UK has ordered an Opsis 400 emissions monitoring system from Enviro Technology Services plc to measure SO2 levels at its site at Stewartby, near Bedford .

Some seven years ago the Company had looked at the possibility of continuous SO2 monitoring but found that the technology was not sufficiently advanced. However, following recent discussions with the Environment Agency, Hanson undertook to re-investigate and began an intensive trawl of possible equipment and suppliers.

The monitoring situation at the 100-year old site is not straightforward. The stack concerned is a brick chimney with walls some 1 metre thick and an internal diameter of 4.5 metres. The process, firing Fletton bricks in a Hoffmann kiln, utilises natural draft, therefore the gas mix may not be homogenous – all of which pointing towards a cross-duct system.

A short list of potential suppliers was established. The Opsis system, although not the most expensive, emerged as the firm favourite. Discussions followed with Dave Curtis, independent consultant, who confirmed that Opsis was the best option.

The trials commenced in April 2001 and were immediately successful. Ian Walker, Technical Manager, of Hanson Brick admits to being impressed by the equipment’s efficiency. “The equipment worked well from day 1. Although the trial installation was rather crude, the resulting data appeared very reliable with minimal maintenance”.

A sampling platform has now been ordered and a date agreed with the EA when the system will be fully operational.

In addition to SO2 measurements, the Opsis 400 will be used to monitor water vapour for correction purposes. Hanson Brick also intend to buy an ultra-sonic flow meter and integrate an existing dust monitor into their monitoring set-up.

The Opsis System 400 is a cost effective, high-performance, monitoring package that utilises DOAS (Differential Optical Absorption Spectroscopy) technology allowing continuous monitoring of several compounds sequentially. Fast response, reliability and multi-analytical capabilities, together with not only information on concentration but also on standard deviation and light level, leads to a system providing a comprehensive and thorough analysis and evaluation of data.

Hanson Brick has been producing bricks for over 200 years. The company is a leading manufacturer with 14 factories and around a 30% share of the UK market. Hanson Brick manufactures over 200 different brick types, which include the product ranges of London, Butterley, Kempston and Desimpel used extensively throughout the UK building industry. The environmental management system at Stewartby works is certified to ISO 14001.

Opsis systems are available in the UK from Enviro Technology Services plc from whom further information on emissions and brick production monitoring is available.

Issued on behalf of:

Enviro Technology Services plc

Kingfisher Business Park

London Road

Stroud, Glos. GL5 2BY

Tel: 01453 733200 Fax: 01453 733201

Email: [email protected] Web:

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