It is important to recognize that the amount of tubing, the size of the sample port and the volume of static oil in relation to the location of the sample port can all disturb the overall quality of the sample. For an effective, data-rich sample, appropriate pre-sample flushing volumes should be included in sampling procedures and should be specific for each individual sample port. The industry rule of thumb is to pre-flush six to 10 times the total volume of static oil in a sample tube, port, port adapter and any dead legs of pipe in the systems upstream of the sample port location.
One of the biggest culprits for letting dirt into hydraulic and oil reservoirs is the air breather. Many systems come with a standard paper media breather with a nominal rating of about 40 microns. This allows the smaller, more destructive particles to get into the system very easily. Upgrading a standard breather to a high-efficiency filter is easily done using commercial bayonet adapters and quality synthetic hydraulic filters.
Avoid damage to drums and other large containers during handling. Negligent handling can cause leakage or ingression of dirt. Each container for in-plant lubricants should be used for only one oil, clearly marked for it and not substituted for another container. It also should be kept clean and sealed to keep out dirt. Never mix lubricants.
Corrosion inhibitors are additives that suppress oxidation and prevent formation of acids. These inhibitors form a protective film on metal surfaces and are used primarily in internal combustion engines to protect alloy bearings and other metals from corrosion.
Assuming that no water is emulsified in the system, some reasons for an increase in viscosity of a circulating oil might include:
Unless you have special arrangements, most laboratories retain your oil sample for only a short period of time. Seven to 14 days is typical. When you get back your reports and have a questionable result or want to have additional testing performed, call the lab immediately to avoid the risk of your sample being discarded.
A properly constructed reservoir is more than just a tank to hold the oil until the pump demands fluid. Whenever practical, it should also be capable of dissipating heat from the oil, separating air from the oil and settling out contamination in the oil.