Getting the best out of particle monitoring

08 December, 2017

• When APCs are fitted to systems, the system cleanliness levels they measure surprises a lot of people and their immediate reaction is that the APC is reading incorrectly. Well it is that clean and has been so for a while; it is only with these APCs that we are able to truly measure these levels.

• Another remark is that “it does not have to be that clean”. On hearing this, I cite a quote by the late John Spencer of Vickers Systems (now Eaton Corp.) in 1981: “No system has failed because the oil was too clean.”

• Finally, the low particle counts magnify any changes in the system particle generation rate du to operation, although their magnitude is relatively small, the proportionate increase may be large and ‘alarming’.

Managing cleanliness

The requirements to successfully manage system cleanliness are stated in the opening paragraph; any impediment caused by the above ‘challenges’ can be partially resolved by acquiring more knowledge about the use and application of on-line APCs. This is best achieved by forming a partnership with the manufacturer of the APC rather than ad-hoc on the job learning by trial and error.

The manufacturer will, or should, provide full training on the both the principal of the APC and also its operation, especially in relation to its scope and application, and perhaps tailor the configuration to the application. Experience has shown that this aspect can take a considerable amount of time, so it is not unreasonable for the manufacturer to make a nominal charge for this service. This should be viewed as an investment as it will save the operator a considerable amount of time in the long run and enable the operator to get the best out of the installation.

Conclusion

The use of online APCs can greatly enhance the efficiency of maintenance regimes. In the past, RCLs were mainly founded on experiences with bottle samples. It should also be pointed out that although the costs of some types of APC are considered falsely by some to be prohibitive, these units are in fact relatively inexpensive. So, with today’s affordable, state-of-the-art instruments and ISO 12669:2017, companies should certainly look to review their RCLs.

References:

[1] ISO 12669:2017 Hydraulic fluid power – Guidelines for determining the required cleanliness level (RCL) of a system, International Standards Org., Geneva, Switzerland.

[2] M J Day & J Rinkinen: ‘Contaminant monitoring of hydraulic systems – the need for reliable data’, presented at COMADEN 97, Tampere University of Technology, Tampere, Finland.

[3] M. J. Day & C.Galletly: ‘Reducing the lifecycle costs of marine systems by fluid cleanliness management.’, presented at ‘Tribology At Sea’, University of Southampton, 28th June 2006, I Mech E , June 2006.