Archive for May, 2015


Last week, I received an email query from Kevin H:
Hi, do you know the RLU limit for diesel i see the IATA say

Here’s my response:

Thank you for your query about the existence of an RLU criterion for ATP-bioburdens in non-aviation distillate fuel.

When I suggested the HY-LiTE test low, medium and high levels, I basically translated from the culture test criteria I had developed from the decision matrix I had been using for BCA’s Biodeterioration Risk Assessments. (high risk: CFU bacteria/L fuel >100). That 100 CFU/L equals approximately 1,000 RLU/L.

At the time I was collaborating with Merck to help them have the HY-LiTE method become the basis for an ASTM standard test method. The HY-LiTE works quite nicely in Jet A, where additive usage and water content vary little among samples.

Regarding the relationship between microbial loads and damage risk:
1. I’ve been doing fuel microbiology for about 40 years.
2. I’ve seen systems that have had high levels of contamination, but no evidence of damage, and systems with low levels of detectible microbial contamination and substantial evidence of microbially-caused damage (filter plugging, system corrosion, degraded fuel, etc.). We still don’t have a reliable model for figuring out when a non-damaging population is going to start causing problems (very similar to humans: there are 10x as many microbes as human cells in and on our bodies. Normally they keep us healthy, but sometimes the same microbes cause disease). Key here is that there is no clear link between microbial load and damage risk. Moreover, microbes found in the fuel are generally not the ones to worry about. It’s the microbes growing on the fuel system surfaces. We work with fuel samples, because they are easier to collect. For this reason, both the EI Petroleum Microbiology Committee and ASTM Fuel Microbiology Working Group advise against setting criteria levels for microbial contamination in fuels or fuel-associated waters. The microbiologists on the IATA microbiology task force also resisted resisted putting criteria into the IATA document until the non-microbiologists wore them down.
3. BCA’s Biodeterioration Risk Assessment looks at climate, system design, operations, maintenance practice, fuel chemistry, bottoms-water chemistry, fuel microbiology, bottoms-water microbiology and system component condition. ATP is only one of 10 different microbiological tests that I use to assess biodeterioration risk.
4. All that said, given the patchiness of microbe distribution in fuel systems, I and most of the other fuel microbiologist that I know tend to be conservative. We agree that detecting microbial contamination tells us much more than not-detecting it. Any positive test result indicates a need for further testing. 1000RLU/L equals approximately 100 CFU/mL = 0.1 CFU/mL. In the UK, drinking water is permitted to have 10^6 CFU bacteria/mL (as long as they are not potential pathogens). IATA set a very conservative control level because filter pulling at 50,000 ft can cause an aircraft to fall out of the sky. Filter plugging on the ground can also stalling, but the net impact is not nearly as dramatic.

Long answer to a simple question. Based on their risk tolerance, different companies (particularly marine, rail and trucking fleets) have set in-house criteria. I recommend using ATP as a canary in the cave test. If you get numbers above background, you should run additional tests. I do not recommend relying on any single test when deciding whether you need to take corrective action.

What’s New – 10 May 2015

BCA’s updated site launched on 07 May. This is the first overhaul since Wendy Dalia (then working on her PhD in marine biology) created the original site in the late 1990’s. Although I’ve kept much of the site’s original content, it has been reorganized to make it easier to find useful information. Let me know what you think.

What’s New – June 2014

In January 2014, at TAE’s 19th Tribology Colloquium, I presented th preliminary results of field evaluations that were being performed on LuminUltra Technologies dQGO-M test method. The new ATP test method provides a simple and reliable means of differentiating between fungal and bacterial contamination in metalworking fluids (MWF).

Four international MWF compounders participated in the field evaluation. All of their data were subitted in time for my STLE 2014 Annual Meeting Presentation:

Recent advances in the differentiation between fungal and bacterial contamination in metalworking fluids using modifications of the ASTM E2694 Standard Test Method. Read more…

What’s New – November 2013

On March 11 through 14, 2014, Dr. Neil Canter, Mr. John Burke and I will once again be presenting STLE’s Metalworking Fluid Certificate Training Course. The course will be held in Atlanta, GA. For more information, visit the STLE website…

In January, 2013, at TAE’s 9th Fuels Colloquim, I presented a paper describing modifications of ASTM Mehtod D7687 (ATP in Fuel) that permitted detection of dormant microbes possibly present in fuel samples, and differentiation between bacterial and fungal biomass in fuel and MWF samples. In October, 2013, at the 13th International Symposium on the Stability and Handling of Liquid Fuels, I presented an updated version of the TAE paper.

In June 2013, I was honored to be presented with ASTM’s Award of Merit.

What’s New – January 2013

It’s been a busy couple of months since the November update. This month’s What’s New includes several course announcements, links to four webinars and announcements about two new ASTM Standards.

On February 19 thorugh 21, Dr. Neil Canter and I will be presenting STLE’s Metalworking Fluid Certificate Training Course in Philadelphia PA. For more information see the STLE flier…

Also coming up in March, I’ll be teaching two, one-day courses at Fuels & Lubes Asia 2013 ( On Tuesday, 12 March I’ll be presenting Metalworking Fluid Health and Safety (read more…) and on Wednesday 13 March I’ll be presenting Fuel Microbiology (read more…). Both of these courses present new material and focus on the economic impacts of the issues covered, along with explanations of those issues geared towards folks with backgrounds ranging from non-technical to purely technical. I invite you to join me in Bangkok for Fuels and Lubes Asia 2013.

I’ve now added hyperlinks to four webinars to the BCA website. Two webinars address fuel microbiology issues. And two address metalworking fluid microbiol.

  • The Importance of Biological Monitoring in Liquid Fuel Handling and Biological Monitoring of Metalworking Fluids can be found on LuminUltra Technologies’ webinar archive site. In the Importance of Biological Monitoring in Liquid Fuel Handling I discuss some of the basics about microbial contamination – focusing in on they various types of damage that microbes can cause to petroleum systems.
  • Similarly, Biological Monitoring of Metalworking Fluids offers an overview of metalworking fluid management and the role of effective microbial contamination control in best practice fluid management.
  • The third webinar discusses the economic impact (value proposition) of real-time microbial contamination in retail fuel systems. Did you know that at retail sites in urban areas, where vehicles line up waiting for their turn at the dispenser, flow rate restrictions as little as 10% can cost retailers >$100,000 US per dispenser per year? Find out how microbial condition monitoring can contribute directly to fuel retail profitability.
  • The fourth webinar in this series reviews the economic benefits (again, value proposition) of real-time microbial contamination condition monitoring. If you provide metalworking fluid management services or operate metalworking facilities, this is a must see webinar.

ASTM E2889 Practice for Control of Respiratory Hazards in the Metal Removal Fluid Environment is the first ASTM Standard to list recommended exposure limits for hazardous components of metalworking fluid aerosols. Just as significantly, the Practice provides guidelines for minimizing exposure risks. Read more…

ASTM D2881 Classification for Metal Working Fluids and Related Materials has been overhauled with the addition or revision of nine classifications and definitions. Read more…

ASTM D7847 Guide for Interlaboratory Studies for Microbiological Test Methods is the first ASTM Standard to grapple with the particular challenges presented when designing and performing interlaboratory studies (ILS) to detemine the precision of fuel microbiology test methods. Read more…

What’s New – November 2012

LinkedIn MWF Interest Group Microbiocide discussion that ran from August through September 2012. A question about microcbiocide selection for semisynthetic MWF triggered a lively discussion that included more than 50 posts. Although some of the posts contained useful information, a substantial number were based on limited experience and unsupportable personal impressions. I’ve compiled my contributions to the LinkedIn discussion and had a number of MWF industry experts review them for relevance and accuracy before posting them here. Read my compiled comments…

2001 L.U.S.T.Line article on microbiologically influenced corrosion in fuel system underground storage tanks removed from BCA’s website. In October 2012, I received a letter from the Fiberglass Tank & Pipeline Institute’s (FTPI) attorney, demanding that I remove this article. In the article I had speculated about the likely mechanism and appearance of fiber reinforced polymer (FRP) tank failure if such failure was due to biodeterioration. My hypothesis was based on FRP failure mechanisms that had been reported in the scientific literature (see bibliography). However, as a measure of good will, I have removed the offending article form this website and have replaced it with a PDF of my exchange with FPTI’s attorney. Read more…

Correction – The version of Non-conventional Methods for Estimating Bioburdens in Fuel Systems Rapidly that has been available on the website was missing the Discussion & Conclusion sections. The incomplete paper has now been replaced with a complete version. Read the full paper…

What’s New – August 2012

Fred Passman Presented with STLE’s P.M. Ku Award

At the 2012 STLE (Society for Tribology and Lubrication Engineering) Annual Meeting in St. Louis, MO, Fred Passman was presented with the P.M. Ku Award; the society’s highest award for meritorious service to STLE…

ISMOS-3 3rd International Symposium on Applied Microbiology and Molecular
Biology in Oil Systems (ISMOS-3) in Calgary, Alberta June 2011.

Now available: Microbial Contamination Control in Fuels and Fuel Systems Since 1980 – A Review

What’s New – November 2011

STLE Recording of Real-time Testing of Bioburdens in Metalworking Fluids Using Adenosine Triphosphate as a Biomass Indicator.

A webinar recording of the Wilbur C. Deutsch Memorial Award winning paper that Fred Passman presented at STLE’s annual meeting is now available for viewing…

This webinar discusses the comprehensive process by which the test method that was ultimately developed into ASTM E2694 was vetted in the laboratory and in a 12-week field evaluation at Caterpillar, East Peoria, IL.

12th International Conference on the Stability and Handling of Liquid Fuels

Now available: Can Non-Chemical Antimicrobial Devices Replace or Augment Fuel-Treatment Microbicides – Presented at 12th Intl. Conf on Stability & Handling of Liquid Fuels, 16-20 October 2011, Starasota FL. Fred Passman and his co-authors Gerry Munson and Robert Kauffman evaluate alternative non-chemical technologies; evaluating them for their ability to inhibit microbial growth & proliferation in fuels and fuel systems

ASTM D 7464 Standard Practice for Manual Sampling of Liquid Fuels, Associated Materials and Fuel System Components for Microbiological Testing

Not exactly breaking news, but the publication of D7464 in the ASTM Annual Book of Standards hasn’t been mentioned in earlier What’s New postings. Initially intended to be a few paragraphs inserted into the existing standard – D4057 Practice for Manual Sampling of Petroleum and Petroleum Products – D7464 provides a comprehensive set of instructions for collecting and handling fuel and fuel system sample when those samples will be tested for microbial contamination. Read more…

Links to Passman Webinars and Podcasts!

Visit BCA’s Annotated List of Other Useful Links to find hyperlinks to Fred Passman’s webinar and podcast recordings.

What’s New – June 2011

STLE University Webinar – Emerging Issues in MWF Microbiology: Biofilm Control

Fred Passman will be presenting a webinar on Monday 20 July 2011 from 1:00 PM until 2:00 PM (Eastern Daylight Time). During the webinar he’ll be discussing key concepts that industry stakholders must understand in order to effectively control biofilm accumulation in MWF systems.

For more information see the Webinar flier visit or contact Kara Lemar, STLE education manager at

What’s New – April 2011


An ASTM Standard Test Method, based on LuminUltra Technologies’, has just been approved as ASTM D 7687, Method for the Measurement of Cellular Adenosine Triphosphate in Fuel, Fuel/Water Mixtures and Fuel-Associated Water with Sample Concentration by Filtration. Unlike Previous ATP test methods, the new Method has been demonstrated to not be affected by the Chemical interferences that have limited the overall usefulness of more traditional methods, such as ASTM D 4012and D 7463.


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