Published in September 2008 Australian Longwall Magazine

But one Australian research and development project is looking to put an end to the uncertainty surrounding high-pressure hoses.

The risk of workplace injury involving hydraulic hoses or fluid under pressure is high, with the 2006 fatality at Centennial Coal’s Angus Place and 60 hydraulic fluid injuries claims lodged with Coal Services in the year 2007-08.

Coal Services data from the New South Wales coal industry found claims lodged for hydraulic fluid injuries outweighed electric shock claims for five consecutive years from 2002 to 2007. Thirty-seven claims for hydraulic fluid injuries were lodged in 2006-07 compared with 15 electric shock claims.

As the safety risk remains elevated for those working in proximity to high-pressure hydraulic hoses, there is an impetus to develop a device to detect if a hose is under pressure.

Currently the non-invasive detection of fluid under pressure in hydraulic hoses is non-existent in the hydraulic industry. Unlike in the electrical world where an operator or maintenance crew can “test for dead” before touching conductors, there is no equivalent in the hydraulic world.

A project funded by the Australian Coal Association Research Program is trying to come up with a hose equivalent for the underground coal sector. Under ACARP, Custom Fluidpower is researching and developing a device which would be able to detect fluid under pressure in hoses.

“The need for a scanning piece of equipment for stored energy or pressure trapped in a hydraulic hose has become very vital,” Custom Fluidpower sales director Neil Martin told Australian Longwall Magazine.

“The hydraulic industry has not enjoyed that piece of device so we have embarked for the last 12 months on investigating, researching, coming together with ACARP and now physically going down a path of putting together a prototype that will do this.”

The device is still in its early days but a feasibility study on various different methods of detecting pressure has been carried out by Custom Fluidpower.

Currently the way of detecting pressure in hydraulic systems is by a gauge or centre point which physically connects into the hydraulic system to read the pressure.

Through this method though, an operator must still engage closely with hydraulic oil under pressure. Also, sometimes there is not a point to connect into the system, so the operator has to remove the hose or puts a connection point in without knowing if he is removing a hose which is under pressure.

This uncertainty runs the risk of fluid injection which can result in severe injuries including amputations or death.

Custom Fluidpower is hoping to give the hydraulic industry a device to check if a hose is under pressure and safely allow an operator or maintenance personnel to proceed with work.

“Fluid injection can be done with only a few psi of pressure and [in] some pieces of equipment working above ground or below ground there could be up to 420 bar of active stored energy,” Martin said.

“In some cases you can remove limbs, or cut an arm or a leg off.”

The company narrowed down the method it will use to test for pressure after looking at ultrasonics but eventually opted to look at the way a hose reacts under different pressures.

It is in the middle of developing a table-mounted prototype to test deformations in a hose under pressure. Once it is developed the device will look at deformities which occur within a hose when it is under pressure or not under pressure.

“The hose does behave differently when put under pressure. The device would look at the differential between the two,” Martin said.

The prototype will do a series of tests on different hose makes and models under pressure to create a database of readings.

The hose to be tested will be pressurised and multiple readings of the changes within the hose will be recorded. The same hose will be tested many times to establish the performance stability of the product. The prototype will also upload the hose manufacturer’s information.

Testing of the hoses will be conducted in-house at Custom Fluidpower in Brisbane. For the trials researchers will also take old hoses from machinery on operating sites, pressurising them and seeing how an old hose behaves differently to a new hose.

Martin said that within six to seven months Custom Fluidpower should have a unit ready to take into the field to cross-reference its testing work.

When operational the device will be a hand-held instrument that can be attached to an operator’s belt or stored in a toolbox. It will be able to be easily attached to various hoses to take the readings.

The device would download the data, analyse the outcomes and advise the operator on whether to proceed when operating with the hose.

Martin said to speed up approval for underground coal operations, Custom Fluidpower engineers were selecting already approved and readily available components so that the device would be ready for underground coal operations.

“We will then be developing a small hand-held device and then the next stage would be to make it useful for underground coal mining as well,” Martin said.

“In about 18 months we will have one for use in the market for operators to actually put into service.”