In August, the last thing on the mind of most Texans is building a fire indoors. The temperature in Mansfield, Texas, home to fire suppression foam manufacturer Chemguard, averages 96 degrees F that time of year. Last year was significantly above average. Still, Chemguard needed to build an indoor fire in a round 50 square foot pan several feet deep in heptane.
Required as part of an international test protocol, a fire like this would typically have been built in a far more frigid climate than Texas, said Dr. Kirtland Clark, Chemguard's Vice President of Research and Development.
"This is the first time these fires have been run indoors," Clark said. "It's also the first time the fires were run at atmospheric temperatures of 100 degrees and above. All the other fires have been done in the U.K. or in northern Norway."
Even the fuel temperature and water temperature used were higher than what is normally indicated in the LASTFIRE tests. As if that was not enough, some of the tests were conducted with the overhead door of the massive test building shut tight.
All this simply added another hurdle that the Chemguard AR-AFFF product, Ultraguard 3% x 3%, easily cleared. Eleven batches of fire fighting foam totaling 50,000 gallons were approved for sale to a Middle Eastern country who ordered the testing as a condition of purchase.
LASTFIRE (Large Area Storage Tank Fire Protocol) was developed as a test to assess the capability of a foam to achieve the special performance characteristics relevant to large storage tank fire fighting. The test serves as a standard for this severe application and has been included as a requirement in foam concentrate procurement specifications by major international oil companies.
Richard Coates with U.K. based Resource Protection International, a consulting firm specializing in fire and explosion management, provided third party supervision of the cradle-to-grave testing process. Coates formerly served as the Chief of Fire Protection for BP Corporation.
Typically, manufacturers test their products by submitting samples to a separate location where testing is conducted. However, in this case, the entire production process was monitored by Coates at one location. He sampled the foam as it came out of the blender, pulling out the batch that was tested on the fire. At no time was the material outside his ability to control.
The fire test burns were conducted by Chemguard's senior and very experienced foam chemist, Randy Hendricksen, who himself checked every aspect of the tests from initial blending to the detailed laboratory analysis of every separate batch, Coates said.
"Randy is a consummate professional," Coates said "It was no surprise that while I was at the plant over two weeks, Randy received telephone calls from people both in and outside the USA requesting technical advice on foam and their chemical products."
The actual test is conducted under equally rigorous conditions. A separate LASTFIRE test is conducted for each of the three categories of nozzles used - aspirated, semi-aspirated and a system nozzle that is the equivalent of a foam chamber/pourer. First, the pan is ignited and allowed to burn for three minutes. From a fixed position, a stream of foam is shot into the center of the burning pan for seven minutes.
Foam first moves to the back, then forward around one-foot protrusions on either side of the pan that simulate debris that firefighters may encounter. Finally, the foam seals the surface of the liquid by pushing against the pan's forward edge.
"This is where most products fail," Clark said. "That front edge will continue to burn because many products cannot heal that edge against the heat."
The faster the fire is extinguished, the higher the score. The fire has to be out well before the end of the foam addition to get a high score.
Extinguishment is not the conclusion of the test. Once the foam application is completed, attempts are made to reignite the fire. Finally, a burn back test is conducted in which a sleeve is used to isolate an area of fuel which is reignited. Once the sleeve is removed, the foam must "heal" across the affected area, smothering the flames.
"LASTFIRE is a very special type of fire that requires a mobile foam in order to flow around those one-foot protrusions and yet a foam that has a very low field pickup so that you don't have to put fresh foam over the top of it in the way that can be done in UL testing," Clark said.
UL foam testing is conducted using a one-minute pre-burn in a square pan. The depth of fuel is much shallower than the LASTFIRE test, he said.
"The UL test allows you to train the foam," Clark said. "After you get control you can pick up that nozzle, clean up the foam and cool the edges. With the LASTFIRE test you don't get to cool edges by directing the foam against the wall. It is all dependent on the foam moving on its own to cool the wall, even around the protrusions."
Even the quality of water used was open to variation. Instead of tap water, some tests were conducted using synthetic sea water. The foam's performance actually improved, said Clark.
A key issue with the extended burn times is the amount of large black smoke that billow from the tall burn building during every heptane burn, Coates said.
"The positive relationship that Chemguard has established with their community, fire department and local municipal council is such that these burns are permitted, which in other communities would be banned," Coates said. "Education on the necessity for the practical testing of fire fighting foams and what the Chemguard facility means for the local economy and employment, have ensured that the Chemguard manufacturing facility and foam testing laboratories receive full support from community leaders."
Both Coates and Hendricksen attended a full meeting of the Mansfield City Council to meet officials and elected members should there be any questions over this unique series of extended large scale burns.
"However, no concerns were forthcoming with the mayor and officials who were pleased to support what is a significant export from the town's leading manufacture of fire and chemical products," Coates said.
Being able to provide on site live fire burn testing, expert technical backup and cutting edge laboratory technology, makes good commercial sense and ensures long term product viability for quality fire fighting foams, he said.
Testing does not end with the delivery of the foam. Standard procedure at Chemguard is to store a sample from each batch that can later be tested if there are complaints about the 10-year guaranteed product.
"It keeps you totally honest as a manufacturer and, at the same time, it guarantees to the purchasers a product that fully meets the LASTFIRE requirements," Clark said.