Five Years Seems Like Ages Ago

By Rick Long

Taking lessons learned during the past five years into account, PEI’s Diesel Exhaust Fluid (DEF) Committee recently released the second edition (2015) of RP1100. The document makes technical corrections and clarifications to the original work and adds guidance on several key topics related to DEF storage and dispensing.

As was true in for the first edition, Steve Hieber of PWI Inc. in New Oxford, Pennsylvania, chaired the committee of experts who drafted the revision. Hieber expressed his gratitude for the knowledge and cooperation of all the committee members.

PEI published the first edition of RP1100: Recommended Practices for the Storage and Dispensing of Diesel Exhaust Fluid (DEF) in 2010 in response to changes in federal emission requirements for diesel vehicles and a new diesel engine technology, selective catalytic reduction (SCR).

The emission requirements lowered the allowable oxides of nitrogen from diesel vehicle exhaust. And SCR, which uses DEF for after-treatment of the vehicle’s exhaust, was emerging as the accepted solution to meet those requirements.

That first edition was intended to provide basic guidance on the new DEF storage and dispensing equipment that best would preserve the product’s quality and prevent releases into the environment.

Five years later, SCR-equipped diesel vehicles and DEF-related infrastructure are firmly established as essentials of the U.S. transportation system. Annual DEF consumption in the U.S. is expected to increase from 400 million gallons in 2015 to 1 billion gallons in 2019. And much has been learned in the process by installers, service contractors, fuel marketers and other DEF stakeholders.

Here are eight of the most important changes, clarifications and additions in this version:

  1. Labeling: As the DEF industry has matured during the past five years, so has the regulatory environment in which the industry operates. One regulatory development has to do with labeling requirements. Effective January 1, 2016, the National Conference on Weights and Measures (NCWM) added requirements for the labeling of DEF dispensers to its Handbook 130, the document that covers engine fuels, liquids and fueling systems. “Handbook 130 has been adopted in full by nearly 20 states, and many other states accept portions of the document,” Hieber said. “The PEI DEF Committee felt it was important for users of RP1100 to know that specific language is now required on DEF dispensers, so we amended Chapter 6 to point users to Handbook 130 for those labeling requirements.”
  1. Material Compatibility: To prevent contamination or an unintended release, equipment that comes into contact with DEF—including tanks, dispensers, piping and other associated components—must be compatible with the product. The 2010 version of RP1100 included examples of compatible and incompatible materials referenced in two standards: the International Organization for Standardization’s ISO 22241 and the German Institute for Standardization’s DIN 70070. The 2015 edition removed the reference to the DIN standard.

“ISO 22241 has gained wide acceptance in the industry in the last few years,” Hieber said. “DIN 70070, on the other hand, is seldom cited and has essentially become obsolete. As a result, the committee thought it would be unwise to reference both documents in the new edition. In particular, we wanted to avoid any opportunities for conflict or confusion if one of the standards changed in the future and the other did not. Given ISO 22241’s prominence, sticking to that standard was the obvious choice.”

As in the first edition, however, the reference to ISO 22241 is not meant to specify the only materials that are compatible.

“While we elected to defer to the work ISO has done in identifying compatible and incompatible materials, readers should be aware that the ISO materials lists are for guidance only,” Hieber said. “Manufacturers may test other materials for compatibility with DEF as long as the test conditions reflect the expected temperature range and contact time to give a fair assessment of any material degradation or other effects.”

  1. Quality: The introduction of impurities will degrade DEF and negatively affect the performance of SCR systems. The first edition of RP1100 stressed the importance of maintaining product quality throughout each phase of storage and dispensing. “For this edition, the committee decided to go even further by giving users some guidance on how to ensure that the product is still on spec,” Hieber said. “One often-used tool for doing that is a DEF refractometer, which tests the concentration of urea in the DEF, so we mentioned that approach in the new document.It’s important to mention, however, that the committee did not go as far as it could have with specific sampling and testing procedures for determining DEF specifications. The reference to refractometers simply states that the use of this device is ‘one way’ to do it.”
  1. Underground Storage Tanks: As DEF quantities have grown during the past few years, underground storage tanks (USTs) have become a common solution for storing the product. The 2010 edition gave early guidance on DEF USTs, noting specifically that:
  • All DEF USTs should be double-walled, have secondary containment with monitoring, or both.
  • The inner tank must be constructed of compatible materials.
  • The inner tank and outer containment must be liquid-tight.

The new document further refined the tank requirements: “Hydrostatic monitoring systems, in which the interstitial space is filled with brine, clearly would cause contamination of the DEF if the inner wall were to leak,” Hieber said. “In the new edition, the committee pointed out this danger, in effect recommending the use of tanks with a dry interstice.”

  1. Overfill Protection: Sometimes one word makes all the difference. A change to section in the revised RP1100 is an example. This section, which addresses overfill prevention, previously stated that tanks “should” be equipped with overfill protection. The new sentence states “equip” DEF USTs and ASTs with overfill protection. The committee’s deletion of the word “should” turned what had been a suggestion into a requirement. This change represents a clear decision in favor of overfill protection.


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