Above: Kittiwake Hydraulic Particles Test Kit
Comment
Top-up is a frequent source of particulate contamination. Keep filters and vents in good order and containers tightly sealed.
Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.6 Hydraulic Oil >> 7.6.4 Particulate Contamination
Hydraulic systems vary with regard to the way in which they are required to operate. Some equipment only operates occasionally and for short periods, whilst other equipment will operate for extended periods virtually continuously. As well as there being a wide variation in time in use, there is also wide variation in scope for contamination to occur and tolerance of the equipment to contamination should it arise. Tolerance to contamination is largely a function of operating pressures and the impact this has on oil film conditions at critical elements within pumps and motors.
Particulate contamination within hydraulic systems can arise from internal sources such as the top-up oil and the surrounding air. Particulate can also be generated internally within the systems, for example from wear, rust and material such as mill scale from pipe and weld surfaces. Achievement of problem-free operation of hydraulic systems is highly dependent on maintenance of cleanliness and this is a critical maintenance function.
A variety of techniques are applied ranging from particulate counting; particulate counting coupled with sizing; and ferrography. Ferrography aims to determine the amount of contaminant plus characterisation in terms of shape/colour and likely source of contaminant.
Comment
The variation in scope for contamination to occur is mainly determined by: the frequency with which fresh oil requires to be introduced into a system (i.e. amount of leakage occurring); the extent to which water can enter the system and cause corrosion.