Hydraulics & Pneumatics March 2022

HYDRAULICS 40 HYDRAULICS & PNEUMATICS March 2022 www.hpmag.co.uk Why do we need cleanliness specifications? We’ve seen how important it is to operate systems and processes with clean hydraulic fluid - and keep that fluid clean throughout the processes’ life. But you can’t control what you don’t measure – and this is the basis of any quality system, especially a Cleanliness Management system. So, to control cleanliness, we need an appropriate specification to compare our measurements with. The RCL should define the cleanliness - from the design phase, through manufacture and onto its operation. There are several methods currently available to select the RCL, including the new method outlined in ISO 12669, which will give the RCL to suit the individual requirements of the operator. Although the RCL is essentially a system requirement, it is much, much more than that as it dictates the cleanliness throughout the life of the system, namely: The design of the contamination control aspects of the system The cleanliness level of the production and assembly facilities The cleanliness of machining and wash fluids used in the production of components The cleanliness of the fluid in the component test rig The cleanliness level that must be achieved after system commissioning and flushing and immediately prior to delivery to the end user The cleanliness required in service so that the life and reliability required by the end-user is realised The RCL is used to set maintenance action levels How do we obtain the most appropriate RCL? Currently, there are several ways designers and users can select the RCL for In the last issue of Hydraulics and Pneumatics, Mike Day, managing director of CMS Consultants, showed how the cleanliness of hydraulic system fluid has improved over the years. This month’s article by Mike Day – co-authored by Wayne Hubball, technical director of Reynolds Contamination Control – looks at the Required Cleanliness Level (RCL) and explains why selecting the most appropriate RCL is the foundation of a Cleanliness Management Programme. a system and these are identified below. Unfortunately, there is insufficient space to describe these, and they are described elsewhere [1]. Component manufacturers’ recommendations Recommendations by industrial and academic organisations Recommendations based on practical experience Recommendations by filter manufacturers Laboratory contaminant sensitivity testing It’s doubtful whether any of these methods will give the most appropriate RCL for a specific system, as they all focus on a different aspect of the operation and are generally a generic value as the specific requirements of a user are rarely taken into account. Also, most are based on historic data which may be out-of-date and not really suitable for the more modern machine being designed, Certainly, few – if any – take into account the requirements of a specific user. Of perhaps greater importance, is that the RCL given by them Have you reviewed your hydraulic cleanliness specification lately?