A Few Questions About ASTs

Question #1: Does a double-wall tank need secondary containment?
Answer:  According to the US EPA, a double-wall tank will provide secondary containment when certain equipment is installed. Please see this EPA Memo


Question #2: How do Fireguard and Flameshield Tanks differ?

Answer: For a good comparison of these tanks, please read this article published in Tank Talk, in May 1999. Further, an explanation about Flameshield as it relates to various editions of the Model Fire Codes can be found here.


Question #3:  What is the R-Value of the insulation used in Fireguard Tanks?

Answer: In an experiment conducted to find the insulating value of Fireguard concrete insulation, the thermal resistance of the insulation was found to be 0.7 (hr-°F-sq.ft.)/(Btu-in.). This is compared to the thermal resistance of fiberglass insulation that is used in your house of 4 (hr-°F-sq.ft.)/(Btu-in.).

Thermal resistance is defined as "a quantity expressing the ability of a substance to prevent a heat transfer; equal to the temperature difference across the surfaces of the body divided by the rate of heat transfer."

This means that 3 inches of Fireguard insulation will have an R-value of 2.1 (hr-°F-sq. ft.)/(Btu).  This is calculated as 0.7 x 3. The R-value of 3 inches of fiberglass insulation is 12 (hr-°F-sq. ft.)/(Btu) and the R-value of mineral wool insulation is nearly the same as fiberglass.


Question #4:  Does Fireguard meet the California Air Resorces Board (CARB) requirements?

Answer:  STI/SPFA licensed Fireguard® Tank passed the Standing Loss Control portion of the new CARB EVR (enhanced vapor recovery) certification requirement on October 3, 2008 as announced in this press release. The CARB Executive Order for new installations is found here and for existing installations is found here.

CARB has provided this advisory with an explanation of the EVR requirements.


Question #5: What are the set-back distances required by the fire codes for aboveground tanks?

Answer:  Each local jurisdiction has its own fire code requirements.  However, most jurisdictions reference one of the Model Fire Codes.  Charts showing the set-back requirements for aboveground tanks used for motor vehicle dispensing per the most recent fire codes revision cycle can be found here.


Question #6:  Does Fireguard comply with UL 2085?

Answer:  Here is the UL Certificate of Compliance issued in 1998 and here is the UL Certificate of Compliance issued in 2007.  The 1998 Certificate refers to the current fire codes at that time and the 2007 certicate references the updated fire codes. In addition, here is an explanation of the performance tests required by UL 2085.


Question #7: Why are there so many different fire tests for tanks?

Answer:  There are only a handful of Nationally Recognized Test Laboratories here in the US, with both UL and SwRI being among them.  They are the only two test labs that both test and List storage tanks - UL and SwRI.  As for the test standards, all three (SwRI 97-04, UL 2080 and UL 2085) have the exact same requirements for the fire test itself.  The test is a 2000 degree furnace test for two hours (along with other aspects of the test spelled out in detail).  What varies is the pass/fail criteria for each of these tests.  When NFPA first developed a definition for a fire resistant tank, they believed that at the end of the test, the tank simply needed to serve its basic function.  They felt it was critical that the tank continued holding its product, that the supports continued to support the tank and that the emergency vent continued to operate.  To meet this criteria it was not necessary for the interior of the tank to remain below a specified temperature.  UFC took a much different approach which is what the Fireguard tank is based on.  UL 2080 was developed by UL alone based on their own criteria.


Question #8: What are the requirements for venting and emergency venting for tanks?

Answer: Tank venting is a complex subject that relies on the expertise of tank and vent manufacturers, testing laboratories, mechanical engineers who may be charged with designing vent piping extensions, product specialists who must be familiar with the properties of stored liquids, and the local authority having jurisdiction who is charged with interpretation and enforcement of code requirements. Accordingly, the answers offered in this article was written by Jeff Shapiro, PE and FSFPE of International Code Consultants answers some of these questions.  The answers are general in nature and should not be used in the absence of qualified experts responsible for overseeing the design and installation of tank vents.

Question #9:  Will a Fireguard tank meet the furnace test requirements for a Protected Tank if the test is extended from 2 hours to 4 hours?
During the furnace test performed by UL at their facility for the Performance Testing required by UL 2085 for Protected Tanks, the test duration was extended from 2 hours to 4 hours.  See this letter from UL regarding this testing.  Note that this data refers to tanks with 6 inches of insulation (rather than 3 inches).