Have you ever gotten milk from the grocery and later opened it only to find it had already gone bad? Bought a carton of eggs and found a couple were cracked? These things happen. Even if 99.999 percent of the time everything is perfect, that .001 percent can pose a big risk to your health. Just like those eggs from the store, machine oil can be defective and pose risks to the health of your machinery.
The key is not to allow defective products into your machine systems—that’s where testing is mission-critical. In this article, we’ll walk you through the absolute must-checks before you put your new oil into service.
A Word on Filtration
While many facilities filter their oil, filtration only removes dirt and particles, not the dozens of other contaminants and potential issues that can lurk, hidden in your oils. As such, we highly recommend proper testing for your lubricants.
Test Your Oil for Yourself
Some lubricant suppliers offer oil analysis services, wherein you could send your supplier a sample of newly delivered oil and have them test it. But there’s an inherent conflict of interest involved. While most are honorable, and you can trust them, it’s best to test at least some of the oil with an independent, third-party lab to confirm the results from your supplier’s lab.
Define Your Acceptable Quality Limit (AQL)
The first step in testing is to know what level of quality and consistency you need from your supplier—bottom line, you will get some defective oil, sometime. We do this using the acceptable quality limit (AQL) measure.
An (AQL) is the worst process average (a percentage) you can accept, prescribing the range of the number of defective components considered acceptable when random sampling those components during inspections.
Component defects fall into three categories (specified by the manufacturer):
- Critical
- Major
- Minor
What are your product quality controls? Is your AQL 95, 97 or 99.99 percent? As you set this, keep in mind small percentages on a large scale can create massive waste.
For example, the world’s biggest oil producer refines 241 million gallons of oil each day. With an AQL of 99.9 percent, that’s 241,000 gallons of defective oil per day—88 million gallons per year.
Bottom line, you can’t know your oil is acceptable if you don’t sample and test it, and you’ll need a nice, high quality standard that your supplier can still meet.
Once you’ve defined your AQL, it’s time to start testing for a variety of potential issues.
Types of Testing
Several types of testing can quickly tell you whether or not the brand new oil delivered to you is, in fact, suitable for your system:
- Viscosity Testing—Test with viscometers to ensure you get the correct grade (if your oil is too low a grade, it can massively impact your system)
- Particle Counting—Will help you determine how much filtration is necessary; you can use many quick, simple particle counters
- Offsite Testing—After viscosity and particle tests are performed, it’s best to take your oil to a third-party lab offsite that can run a series of tests
Drawing a Proper Oil Sample
The first key to proper testing is taking a proper oil sample. Here’s a step-by-step guide to help you through the process.
- Preparation
- Confirm the port ID plaque matches the work order
- Remove plug from tank opening
- Clean any exposed ports
- Hardware flushing
- Insert one end of your new nylon tubing into tank and the other end into vacuum pump; don’t tighten the knurled nut on the sampler to allow air to vent during sampling
- Loosely thread on the purge bottle
- Purge 10x estimated dead volume by pumping vacuum pump
- Loosen knurled nut to stop flow
- Remove flush bottle
- Sample bottle preparation
- Open sampling bottle
- Tightly thread sampling bottle onto sampling pump (nylon tubing end must puncture bag)
- Sampling
- Pull vacuum pump handle to extract oil sample
- Fill bottle no more than 75 percent full
- Stop oil flow by loosening knurled nut to break vacuum
- Extract tubing from tank
- Labeling
- Unthread sampling bottle from vacuum sampler
- Tightly secure cap without opening plastic bag
- Write required data on label
- Attach label to sampling bottle (if it’s not already attached)
- Cleaning
- Detach and discard tubing
- Clean sampling pump and place in a plastic bag
- Wipe clean and reinstall dust cap on sampling valve
- Wipe any fluid spilled on machine
- Dispose purged fluid, nylon tubing and any used, lint-free cloth (in accordance with your plant’s environmental policy)
Incoming Oil Tests
We recommend conducting the following tests for incoming oil:
- Viscosity at 40 degrees C (ASTM D445)
- Viscosity at 100 degrees C (ASTM D445)
- ISO particle count (ASTM D7647)
- Acid number (ASTM D664, D2896, D974, D3339)
- Karl Fischer moisture (ASTM D1744 or D6304)
- Elemental spectroscopy (ASTM D5185, D6595)
- Fourier transform infrared (FTIR) spectroscopy (ASTM E2412)
Tests by Fluid Type
Compressor, Gear, R&O and Turbine Oils:
- Color (ASTM D1500)
- Foam stability/tendency (ASTM D892)
- Demulsibility (ASTM D1401, D2711)
- Linear sweep voltammetry (ASTM D6810, D6971)
Hydraulic and Motor Oils:
- Varnish potential (ASTM D7843)
- RPVOT (ASTM D2272)
Maintain Top Cleanliness Standards
The health of your equipment and machine systems depends on the quality of your oil. Sub-par oil can cause component failures, equipment malfunctions and costly plant downtime. It’s crucial to your oil and your plant that your oil analysis program provides for proper oil sampling and testing of new oil deliveries.
At Energy Services International, we can help. We have more than 15 years of experience in oil sampling, analysis, testing, cleaning and flushing. We’ve helped major plants worldwide ensure total oil quality in their machine systems, extending the life of critical components, equipment and whole systems. Partnering with independent, third-party testing services, we ensure total peace of mind for your lubricants and your plant.