Concentrate – a precious resource
Published: 02 April, 2009
Not having the right foam proportioning equipment could seriously hurt your bottom line.
The NFPA has a rule covering foam proportioning. NFPA 1901 stipulates that when proportioning foam greater than 1 per cent (and it is common to see 3 and 6% recommended foam/water mixtures recommended for class B fires), there should be an error rate of between -0 to +30% of the required concentrate – or 1% point, whichever is less.
Michael P Dupay, Marketing Manager of FoamPro, explains that this means that fire brigades can use a proportioner that mixes with water up to 30% more concentrate than what is needed, and still comply with the regulations. When this rule relates to 3% solution, Dupay adds that firefighters have to put three gallons of concentrate per 100 gallons of water, which at 30% accuracy margin comes to 3.9 gallons of concentrate margin allowable. “This is also less than the one percentage point stipulated by NFPA.”
But things change when the rule is applied to higher percentage foam concentrates. “Suppose you had a 6% concentrate foam. If you are supposed to inject at 6%, that’s 6 gallons per 100 gallons of water. The rule says you cannot inject less than the 6 gallons, but it allows you to be 30% rich in concentrate. When dealing with 6% foam, 6 x 30% equates to 1.8 gallons per minute of extra foam concentrate for error margin. However, NFPA says that the standard’s error margin is 30% or 1 percentage point – and this is important – whichever is less. So according to the rules, the error of margin is not 1.8 ie 30% of 6 gallons of concentrate, but 1 gallon.”
Dupay’s concern is that brigades using some of the older proportioner technology (such as eductors) may struggle to comply with these rules, particularly when it comes to the lower concentration foam mixes. “These systems are limited by their technology and external circumstances. Mixtures can be lean or rich if incoming pressures water pressures vary, nozzles have not been properly matched, long hose lays or elevated nozzles create high back pressure. FoamPro microprocessor driven technology simply measures water flow and injects the appropriate amount of concentrate as set by the operator. If there is no water flow it does not inject. We advertise an accuracy of +5% but all our testing comes well below that.” In addition, the system provides real-time and complete operation performance information. “Management can easily be advised of total amount of foam and water used for reclamation”. What about the bottom line?
Dupay highlights that in a class B situation some monitors use 1000s of gallons per minute. He offered a scenario where concentrate costs $20 per gallon, with a 10,000 gallons per minute flow rate, a 3% proportioning rate, and a 10 per cent inaccuracy rate (acceptable under NFPA rules).
Wasted foam calculations are astounding; 30 extra gallons per minute; 1,800 extra gallons per hour; 18,000 extra gallons per 10 hours. The costs are $600 dollars per minute; $36,000 per hour; $360,000 per 10 hours, wasted.
At 30% inaccuracy rate, 3%, and 20,000 gallons per minute, the figures more fabulous, with the cost of wasted foam reaching $2,160,000 per 10 hours. This is not something to be sniffed at.
