Published in the September 2010 Australian Longwall Magazine

Given the kind of pressure used in hoses to move roof supports and other heavy equipment underground, just a tiny pin-prick hole in a hydraulic hose can unleash a fatal jet of fluid capable of puncturing through skin and flesh.

While many risks can be minimised, the nature of hydraulic power is difficult to mitigate.

High-pressure hydraulic fluid injuries have occurred during scheduled maintenance and when fitters have followed existing isolation procedures.

While the valve seals might be closed on either side of a connected hydraulic hose, there is no guarantee the seals will always work, or that there is no deadly silent and high-pressure remnant force left inside.

To overcome this issue, Custom expects to release its intrinsically safe Portable Detection Device for Pressure in Hydraulic Hoses (PDD) in about a year.

Part of a project funded by the Australian Coal Association Research Program, the device is essentially a clamp about 20cm in length that can test hoses up to 1.25 inches in internal diameter.

Applied externally, the PDD indicates whether the pressure inside the hose is dangerously high or safely low by displaying an “H” or an “L” on a small LCD screen.

High pressure is considered to be anything exceeding 15 bar, a level which could cause injury.

Custom engineer Liviu Schintee is the brains behind the device and was influenced by the non-invasive pressure measurement devices used in medical systems.

He said the PDD provides another check to make sure maintenance staff know they actually have low pressure in a hydraulic hose before they get to work.

The device can test the pressure within hydraulic hoses that are old, brittle or have lost their elasticity.

It even surprised most of the old hands at Custom’s branch in Newcastle.

“Everybody in the workshop used it because they couldn’t believe that it is actually working,” Schintee said.

“So they tested pretty much every hose in the workshop.”

So far, Custom has developed the first market-ready prototype of the device, but there are bigger plans for the next generation prototype.

Schintee said the next version could use a USB port so the PLC of the PDD can be uploaded with data to make it accept a larger range of hoses.

This content would be made available for download from Custom’s website, from that point workers could just connect the PDD to a laptop in the field and transfer the data across.

At this stage Custom is yet to decide on whether it should make a PDD which caters to all hydraulic hose sizes used undergroundor one for bigger hoses and another for smaller ones.

Schintee said he wants the PDD to be able to accept all hoses up to a 2 inch internal diameter and a 2.5 inch opening.

Custom plans to release the non-intrinsically safe version of the PDD in approximately 2011 while the PDD for longwall mines will take longer due to the delays in the IS approval process.

Schintee said some parts might be sourced in Germany, but otherwise the bulk of the PDD will more than likely be manufactured in Australia.

The device is also expected to eliminate some of the guesswork that might arise in some situations.

In the case of a conveyor underground with about 10-12 hoses, Schintee said other machines might still be operating but a fitter might be 90% sure of the hose he wants to repair.

“But maybe that’s not the hose, so you can test it with the PDD device to see if that’s the hose that has actually been isolated.”

Custom has applied for patents to protect its PDD and expects the device to have export potential.