Gem trap steamed up in safety row

Inventor disputes study suggesting flaws in working of non-mechanical steam trap

A dispute over the safety of an award-winning steam trap is costing its inventor thousands of pounds in lost orders, he claimed last week.

Tests carried out at Liverpool University indicate that the Gardener Energy Management (Gem) steam trap, winner of the 1998 Engineering Council Environment Awards for Engineers, will not work under the conditions most prevalent in industry.

The findings are hotly disputed by Gem trap inventor Tim Gardener, who claims that publicity surrounding the Liverpool University research has lost his company orders.

Steam traps drain and eject water from a system without allowing steam to escape. Most are mechanical but the Gem steam trap has no moving parts, being based on a venturi – a convergent-divergent pipe in which a stream passes through a narrowed section.

Professor Ieuan Owen, head of mechanical engineering at the University of Liverpool’s mechanical engineering department, said his tests showed that the Gem trap was only suitable for use with stable processes which do not fluctuate in condensate load and pressure.

`The crux of the argument is that an orifice trap [Gem trap] will pass a certain amount of water when it’s got a particular pressure on it. But for a varying condensate load, the trap will not cope,’ said Owen.

He added that this lack of dynamic capacity meant the Gem trap could either pass steam out of a system or back up water within it. `If there’s condensate sloshing about in the line you can get damage to the steam system,’ he said.

Gardener disputes Owen’s claims, pointing to the `flash steam’ that gives the Gem trap its ability to deal with varying loads.

At cold start-up, water jets straight through the Gem trap `as if it was a simple hole’, Gardener said. At its running load, the trap preferentially discharges condensate, rather than `live steam’. Flash steam condenses down-stream of the trap, created by high-pressure, high-temperature condensate moving to low pressure. `The back pressure within the discharge throat, caused by flash steam, gives the trap dynamic capacity,’ said Gardener.

Owen has worked for Spirax Sarco, which produces rival mechanical traps, but he said the Gem trap tests were not carried out for Spirax Sarco and not funded by it. `It’s an undergraduate project. I test lots of components to give the students something to work on,’ he said.

Copyright: Centaur Communications Limited