In the article, Utah-based Fluid Power Safety Institute director Rory S McLaren warned that the use of ball valves to lock out shields for maintenance purposes may not be failsafe.

The problem was recognised about two years ago in Australia by Lindsay Auston of Longwall Advantage, a company that sells and develops specialist engineering solutions for hydraulic systems and pumps.

Auston identified the issue after completing a hydraulic safety audit at a New South Wales longwall mine.

Pump specialist Tim Leeson, who recently started Inoxihp Australia, became involved and decided, in the absence of a suitable solution, to come up with a simple device to resolve the problem. A prototype valve has since been developed by Inoxihp Australia, which eventually aims to manufacture the valve for worldwide distribution.

“Our target was to achieve a manual interface that is as simple and as obvious as operating a ball valve, but having a more sophisticated function, making the procedure safer and fool-proof,” said Leeson.

Leeson said a number of designs were considered before settling on a valve assembly that met the following criteria:

Single manual operation, ie one handle

Lockable

Full flow capacity

WP to 350bar

Suitable for pressure port sizes from 1/2" to 2"

Isolates and depressurises a PTO service, (RS or BSL)

Depressurises the service side to return

In the isolated position opens the service side to atmosphere to ensure ZERO pressure

Visually indicates status

Cost-effective when compared with similar compilation of components, ie 3 or 4 ball valves arranged on a panel

Compact enough to stand alone or panel mount

“This is something we are quite proud of,” Leeson said, “having taken up a fair amount of time and resources to come up with a working design that satisfies all the operating criteria without compromise.”

Leeson said, to their credit, a queue of responsible longwall engineers had offered field trial opportunities once the prototype was finalised.

Inoxihp Australia supplies a new range of Italian designed longwall pumps to the local industry and was recently given worldwide distribution rights for the products.