FUEL & FUEL SYSTEM MICROBIOLOGY PART 30 – looking for samples in all the right places

What samples are most useful for microbiological testing?

Earlier this week a colleague asked me to prepare a short piece about collecting samples from fuel systems when the intention was to perform microbiological tests. My initial response was to refer her to ASTM Practice D7463 Manual Sampling of Liquid Fuels, Associated Materials and Fuel System Components for Microbiological Testing and my recently published chapter on sampling in ASTM Manual 1, 9th Edition. My colleague responded that she was really looking for a two-page summary that she could share with her customer who wanted to monitor their fuel systems from microbial contamination. Today’s post provides that summary.

The right stuff…

I first addressed sampling in Fuel & Fuel System Microbiology Part 2 (December 2016) and discussed sample perishability in Fuel & Fuel System Microbiology Part 6 (January 2017), but have not previously addressed sampling directly in this posts. Two key principles lie at the heart of sampling for microbiological testing:

   1) 1. Fuel & Fuel System Microbiology Part 2Samples are diagnostic – not representative, and

   2) 2. Microbial communities develop at interfaces.

What’s a diagnostic sample?

Microbiological sampling is unique in that the objective is to capture a sample from a location that is most likely – within a fuel system – to harbor microbes. Our intent is to diagnose the risk of microbes causing damage (biodeterioration) to either the fuel or fuel system. This is in stark contrast to the more common objective of collecting a representative sample – one that we can use to determine whether the product is fit for its intended use. Consequently, I use the term diagnostic to differentiate microbiology samples from fuel samples.

What is an interface?

Interfaces are zones where two or more components of a system come into contact with one another. Figure 1 illustrates the interfaces found in fuel systems:

• Fuel-vessel – the surface of tanks and other system components that are in contact with fuel.
• Fuel-water – the surface at which fuel and fuel-associated water meet. The primary fuel-water interfaces are between fuel and bottoms-water, and between fuel and biofilms (slime layers) coating system surfaces.
• Fuel-headspace – in fixed roof tanks, the fuel’s surface that is in contact with the tank’s air/vapor zone (ullage)
• Water-vessel – areas of direct contact between fuel-associated water or biofilm and system surfaces.
• Water-sediment (sludge/sediment) – the top surface of any sludge or sediment layer hat has accumulated on the tank bottom.
• Sludge/sediment- vessel – the interface between sludge or sediment and tank bottom.
• Vapor-vessel – exposed surfaces in a fuel tank’s ullage zone.

The best fuel system microbial contamination diagnostic samples come from tank bottoms or interfaces. In practical terms, these are typically tank drain or bottom grab samples.

Sample collection – bottom drain

Supplies

• Absorbent spill pads
• Alcohol – methanol or ethanol liquid or wipes
• Bottle, clear glass, Boston round, or HDPE, wide-mouthed, 500 mL.
  Note: Clear glass makes it easier to observe phase, particulates, etc. However, analytes, such as adenosine triphosphate (ATP) can adsorb onto glass – making HDPE the preferred container material for samples to be tested for ATP.
• Bucket, 5 gal (20 L)
• Funnel
• Gloves, surgical
• Rags, shop

Procedure

•    1. Place absorbent spill pads on ground around drain to ensure that any spillage or splashing will be captured by pads.
•    2. Don gloves to protect hands and to reduce risk of contaminating sample with microbes from your skin.
•    3. Use alcohol to wipe down exposed surfaces of bottom-drain and funnel.
•    4. If there is sufficient space between ground (floor) and drain, place sample bottle into bucket and place bucket under drain.
•    5. Remove cap from sample bottle, place wide-end of funnel under drain and narrow-end into sample bottle.
•    6. Open drain and fill sample bottle approximately 75 %.
•    7. Close drain, remove funnel from sample bottle, replace cap, and label sample bottle with:
        a. Sample source identification
        b. Sample collection date and time
        c. Identity of sample collector
•    8. If sample is not going to be tested immediately, place in ice of refrigerator.

Sample collection – bottom grab

• Absorbent spill pads
• Alcohol – methanol or ethanol liquid or wipes
• Bottle, clear glass, Boston round, or HDPE, wide-mouthed, 500 mL.
  Note: Clear glass makes it easier to observe phase, particulates, etc. However, analytes, such as adenosine triphosphate (ATP) can adsorb onto glass – making HDPE the preferred container material for samples to be tested for ATP.
• Bucket, 5 gal (20 L)
• Funnel
• Gloves, surgical
• Sampler – Bacon bomb or bailer (figure 2)
• Sounding tape

Procedure

•    1. Place absorbent spill pads on ground around drain to ensure that any spillage or splashing will be captured by pads.
•    2. Don gloves to protect hands and to reduce risk of contaminating sample with microbes from your skin.
•    3. Use alcohol to wipe down the sampler and funnel.
  Note: If multiple samples are being collected, and the previous sample contained visible sludge, sediment, or both, use clean fuel to rinse out the sampler before disinfecting its internal surfaces.
•    4. Place sample bottle into bucket.
  Note: This serves two purposes: 1) it reduces the risk of spillage onto ground around sampling bottle; and 2) it shields sample bottle from the view of those who are not directly involved in the sampling process – this is particularly important when sampling retail site underground storage tanks.
•    5. Attach sampler to sounding tape and lower the sampler into the tank until it touches the tank’s bottom but remains vertical.
  Note: Follow standard fuel handling safety precautions to ensure that the sounding tape is properly grounded and that there is no risk of sparking.
  Note: Best practice is to first determine the height of any free-water in the tank (figure 3).
  
  
•    6. Remove cap from sample bottle, place narrow-end of funnel into sample bottle.
•    7. Recover sampler and place it over funnel.
•    8. Drain contents of sampler into sample bottle (figure 4).
  
  
•    9. Remove funnel from sample bottle, replace cap, and label sample bottle with:
        a. Sample source identification
        b. Sample collection date and time
        c. Identity of sample collector
•    10. If sample is not going to be tested immediately, place in ice of refrigerator.

Sample handling

Best practice is to keep samples chilled (40  2 F; 5  1 C) and to begin microbiological testing within 4h after collection Fuel & Fuel System Microbiology Part 6 explains sample perishability. Samples that have been kept chilled can be tested reliably for up to 24h after collection. The total level of microbial contamination and types of microbes present in the sample are increasingly likely to change as sample age beyond 24h. This makes the test results less likely to reflect conditions inside the tanks from which the sample was originally collected. Consequently, the risk of either failing to detect heavy microbial contamination or incorrectly concluding that actually had negligible contamination when sample was heavily contaminated, increases with sample aging. Microbiological tests like ASTM Method D7687 for ATP are easy to run in the field, immediately after sample collection. Using this type of test eliminates the risks caused by sample aging.

The details

This brief explanation of sampling procedures will get you started on the right path. However, circling back my opening comments, I recommend using ASTM Practice D7464 for detailed, step-by-step sampling instructions, and referring to my sampling chapter in ASTM Manual 1 for a full discussion of the considerations that should be taken into account when deciding when and when to collect samples for microbiological testing. I also address sampling in considerable detail in BCA’s six-module fuel microbiology course. For more details about this course, please contact me at either fredp@biodeterioration.control.com or 01 609.306.5250.

Beginner’s Mind – What does this have to do with fluid management?

In the June issue of Lubes’n’Greases, Jack Goodhue wrote a an article about the Zen concept – shoshin – beginner’s mind.  Normally a fan of Jack’s Your Business column, I was surprised by how far off the mark he was in his understanding of shoshin.  I wrote a letter to the editor to express my concerns, and a condensed version of my letter was published in this month’s issue. I believe that when used appropriately, shoshin is of tremendous value to business leaders.  My full letter to the editor (Caitlin Jacobs) provides a more detailed argument than the version of the letter as it appeared in Lubes’n’Greases. I’ve copied and pasted it here.  In the version below, I’ve added a few links to articles that explain shoshin in more detail than I have in my letter. I look forward to reading your comments.

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Dear Caitlin:

I generally enjoy reading Mr. Goodhue’s Your Business articles in each month’s LNG, but found myself scratching my head while reading his critique of shoshin in his June 2019 offering. His comments made me think of novice mariners failing to recognize that, as important lighthouses are as aides to navigation, their very presence represents a hazard to navigation – follow the line of sight track toward the beacon for too long and you’ll run aground.

No doubt, Mr. Goodhue accurately reported Mr. Fogel’s comment about shoshin. It’s a shame that he didn’t then do a bit of research on the beginner’s mind concept before writing his essay. Prof. Daniel Kahneman, a psychologist who is also Nobel laureate in economics has waxed long and poetic about our tendency to be blinded by preconceptions. In many professions, true experts are able to respond to cues and react appropriately seemingly without thought. Air Force Col. John Boyd canonized this ability as the OODA – observe, orient, decide, act – loop in areal combat. The pilot with the shortest OODA loop wins the dogfight. In Prof. Kahneman’s terms this is “fast thinking.” Malcom Gladwell’s “Blink: The Power of Thinking Without Thinking” is a paean to fast thinking. However, as Prof. Kahneman explains in “Thinking, Fast and Slow,” although the ability to react quickly with limited data is no doubt beneficial in some circumstances, it is not universally so. Snap decisions – used inappropriately – can lead to disastrous results. This often the case when complex issues are being considered.

Developing long-term strategic business plans is one example and root cause analysis is another in which a beginner’s mind is more likely to lead to success. As explained by D. T. Suzuki – the Japanese Buddhist scholar largely responsible for expanding western readers’ awareness of Buddhist and Zen thought – the concept underlying shoshin is to strive to become aware of your biases and preconceptions and to – at least temporarily – set them aside when examining an issue. The idea is to adopt an open mind and to avoid drawing conclusions based on preconceptions rather than available, objective information – first observe without judgment (this is the philosophy underlying brainstorming efforts). With a beginner’s mind, one can accept data, ideas, and information without critique – without filtering through the lens of personal bias. Embracing beginner’s mind during the early stages of problem-solving efforts or during the listening phase of conversations makes an individual more receptive to insights they would otherwise miss.

I’ll offer a case study to illustrate my point. In my work with the petroleum retail sector I often hear about filter plugging from clients who would be better advised to report the issue as slow flow. Retail fuel dispensers are set to deliver product at a maximum flow rate of 10 gpm (40 L/min). Although there are typically at least six different phenomena that can individually cause, or collectively contribute to, reduced flowrate, too many retail site operators assume that slow flow is a symptom only of filter-plugging. A shoshin approach would have stakeholders focus on the objective reality – reduced flowrate. And to ask beginner’s mind questions, such as: “What are all of the things in a retail fuel system that can contribute to flowrate reduction?” Note here, no one is asked to discard their previous knowledge or experience. They are only asked to set them aside in order to see the actual situation more clearly. By understanding that premature filter plugging is only one of several phenomena that cause flowrate reduction, stakeholders are better able to develop a cost effective plan to minimize both the risk and impact of fuel dispenser slow-flow (The opportunity cost of flowrates <8 gpm at an urban fuel retail site is >$250,000 per dispenser per year at a site with 12 dispensers, that per dispenser cost translates to $3 million lost fuel sales opportunity. Beginner’s mind thinking could mean $millions in increased revenue).

I fully agree with Mr. Goodhue. “Achieving shoshin would be difficult for most business people or anyone else more than three years old.” So is metadata analysis. The difficulty of achieving shoshin should not discourage either technical or managerial folks from cultivating the skill. The return on effort and investment in cultivating a beginner’s mind can be enormous when the mindset is used appropriately.

Sincerely,

Frederick J. Passman, Ph.D.