Proper lubrication is the single most important factor in ensuring the continued performance of a gearbox, making oil analysis and oil sample is a vital part of keeping your gearboxes reliable. Here are tips for getting the most out of your gearbox oil sampling program.
The Sampling Method - Garbage In, Garbage Out
Proper sampling procedures build the foundation of an effective oil analysis program as the results for the tests done during oil analysis depend on the data contained in the oil sample. It is best to take a used oil sample while the unit is running, during normal operating conditions. Remember, strict adherence to all safety guidelines should be followed.
Points to consider: - Samples coming directly from the sump, reservoir, or drain can contain bottom sediment, debris, particles, and water in concentrations that are not representative of the actual oil condition - Drop-tube (vacuum pump) sampling can also lead to inconsistent reports as typically you cannot guarantee that the sample is coming from the same location, close to the active oil zone, each time you sample - it could be coming from the top, bottom, middle or side
- Both these sampling methods also:
- Introduce outside contamination into your equipment if you're not sampling from a closed system
- Require the equipment to be shut down in order to sample safely
Dedicated sampling valves make it possible to take oil samples faster, with hot active oil, while the equipment is running, from the same spot, every time. Sampling, while the equipment is running, ensures that the sample is a direct representation of the equipment's condition.
Sampling Location Matters
Don't sample directly from the drain. In a gearbox, the oil sitting at the bottom of the case is not really representative of the oil between the gears. The oil just above the drain port may contain many years' worth of wear debris making the samples collected from this location indicate excessive wear when that is not the case.
Here you can see primary and secondary sampling port locations on a gearbox. As the goal is to get a sample from as close to the active zone as possible, to achieve this select a sampling valve that has a permanent sampling tube.
Benefits of Sampling (Pitot) Tubes - The permanent sampling tube ensures that the oil sample is pulled away from the bottom and side sediment - Tubes can be cut and bent up or down depending on the port location - Different tube OD sizes are also available depending on oil viscosity
Sampling From Circulating Lube Lines For most newer gearboxes, it may be possible to sample from a low-pressure circulating return line. In this case, consider a convenient LP Pushbutton valve pre-filter on external circulating lube lines. From here you'll get an easier to take, more representative sample.
Incorporate Other Tools With Sampling
A great program improving objective for teams is to create a closed lubricated system, capable of dynamic sampling, filtering, level checking, topping up, draining free water, and monitoring desiccant breathers. This arrangement saves time, avoids stress with production over shutdowns, and most importantly keeps the equipment performing to expectations.
Desiccant Breathers: - Desiccant breathers prevent moisture contaminated air and particles from entering your system - The clear outer shell provides a visual indicator of the condition of the breather
Filter Gauges: - Gauges such as a color-coded FilterminderTM help as it indicates when a desiccant filter should be changed - The gauge provides an indication of the built-up pressure in the oil vessel that can cause seal damage or blowout, friction, overheating, and loss of power
Level Gauges: - Maintaining the correct level is essential as oil lubricates, cools, and protects the moving parts of your machine - Vent kits options provide a completely enclosed system, preventing outside contaminants from entering the system
Bottom Sediment & Water Bowl (BSW): - Visually inspect for dirty oil, water contamination or excessive wear debris - Drain free water to be easily from the system
NEW Bottom Fluid Retriever (BFR): - Water is a leading contaminant of lubricated systems - Bottom water migrates throughout heated oil when systems heat up, cavitating lubricated surfaces and oxidizing the oil or fuel - Remove that water from the deep bottom of tanks below drain plugs using a low port profile BFR, vacuum pump, and tubing - Replace the water with the required oil to maintain adequate lubrication
Oil Sampling Intervals
Every machine is unique in its intended performance, locality, environment, and maintenance schedules, and this uniqueness, therefore, sampling frequencies should be set specifically for a particular machine. Although, most machinery manufacturers will recommend a fixed sampling interval. Or you can establish sampling intervals based on oil condition. Remember, the optimal sample frequency for any application should be based on your reliability objectives.
In summary, pay attention to your gearbox: - Monitor daily - Regular sampling - Keep contamination out
