Particle contamination can greatly reduce the lifespan of hydraulic components, which is why it is important to check the oil frequently. Some level of contamination is unavoidable, but keep it at a minimum if possible. The level to be aware of will vary across different hydraulic systems and is set by the manufacturer. You should ensure to set the cleanliness level to the lowest ISO code level, which is the strictest threshold.

Hydraulic oil is used to adequately lubricate moving parts such as pumps, motors, and valves. An important component to hydraulic fluid is viscosity, which determines the amount of friction in a system. Too much or too little friction can prevent the machine from doing its job well and lead to breakdowns, costing businesses time and money on repairs. Selecting the proper viscosity grade is best done in conjunction with the equipment manufacturer and lubricant supplier.

Because cleanliness drastically affects the durability of various system components, a new industry trend is to take the duty cycle, operating pressure, and system reliability requirements into consideration. New systems will need to be flushed out before being serviced to remove debris accumulated during building. Do not take shortcuts while flushing out old oil or system components could fail within a short operating time.

Hydraulic systems must be checked regularly for the presence of water, especially in the oil reservoir. The water should be thoroughly drained to avoid buildup, which can result in corrosion, sludge, and even hydrolysis of the additive components. The cleaner the oil, the longer the system will function. Large solids not only lead to detrimental results like pump failure, but it can also result in wear and tear of the pump or cause the valve to stick.

Most systems are equipped with filters to prevent a buildup of particles in hydraulic systems and protect vital components from damage. These filters should be changed and serviced often in accordance with the manufacturer’s instructions. Systems without filters require more frequent oil changes to prolong the life of the equipment.

The cleanliness of hydraulic oils should be monitored periodically to ensure no disruptions during operation. Oil from large systems should be sampled one per year for contamination, viscosity, water content, and amount of particles. There are several ways to measure filter residue such as gravimetric analysis, microscopic examination to determine the size and quantity of residue, and automatic particle counting in a representative oil sample.

These are some generally accepted warning limits for contamination levels:

Filter residue (0.8-micron membrane filters) limits

0 – 50 mg/kg – Clean

50 – 150 mg/kg – Acceptable

150 – 300 mg/kg – Filters should be changed

300 – 400 mg/kg – Heavy contamination

+400 mg/kg – Filter should be replaced immediately\

High-pressure system (above 70 bar) limits

0 – 30 mg/kg – Clean

30 – 100 mg/kg – Should be monitored and filter should be changed

+100 mg/kg – Oil needs change and heavy filtering is needed

Three-quarters of hydraulic system malfunctions are due to particulate matter contamination in hydraulic oil. Prevent disruption to your operation by contacting a professional to perform a checkup on your hydraulic oil.