Trends in the fire industry are slow but persistent. When I started in this industry some 30 years ago, in the USA, a 1000 GPM (4000 LPM) pump was most popular. Over the years, this has risen to 1250 GPM (5000 LPM) and again to 1500 GPM (6000 LPM) pumps. This is a trend that continues to this day.
What drives this? Some of this is the nature of fire response. In the US, very few emergency responses require a truck to pump water at all, and certainly not at full capacity like this. Yet when they need to, they may need to give it all they have. This has led to larger and larger pumps. There are also incentives from insurance organizations that favor larger pumps. There are also bragging rights.
Clarence Saylor was a salesman for the now defunct New Lexington Fire Apparatus, and a good friend of mine and my company. I’d been to his plant in Rockwood, Pennsylvania, which is a small town of about 950 people. I recall we went out to lunch at a local diner because, in his words, “It’s the only place in town that serves food.” In their heyday, they were probably building nearly 100 trucks per year. One day he approached me wanting to build a pumper for his own department, and he wanted the highest flow possible. Local departments in his area had been playing this game for years, and everyone wanted to be championed as the best. Being a good colleague
of Clarence, I took on the challenge. We started with our N2000 model and custom machined the impeller for maximum flow. I recall we got over 2300 GPM (8700 LPM) out of it, making it our highest maximum flow N series pump
in our history. Clarence was ecstatic. But these are bragging rights, not practical points.
New Lexington was located in a largely rural area as were the surrounding communities. It is doubtful that they needed this large of a pump, or that they could supply it with enough water even if they did. That said, even small communities have some large structures, or various difficult to defend facilities such as petroleum storage tanks, that are going to require large amounts of water. While it is possible to make up for a large pump by tasking several smaller models on the fire, this can get unwieldy and difficult to coordinate. The number of hoses and connections make maneuvering difficult, and trucks can get caught in a single position, unable to move, even when conditions have changed, without disrupting the water flow for other pumps. Clearly, there is an advantage to having a single large pump in some circumstances.
Back when I started in the fire industry, a 2000 GPM (8,000 LPM) rating was the largest available. Even these were not terribly popular at the time, as you needed a truck with a very large engine in order to achieve such a rating. But as chassis power rose over the decades, this limitation was overcome. Currently, it is not unusual to see a chassis equipped with a 450 HP (335 KW) or even larger engines. That is good, since for some of the pumps on the market now, that is barely enough.
Pumps on the market now can exceed 3500 GPM (13,250 LPM). Many of these are at lower pressures, say 100 psi (8 bar) and need to be run from huge water mains to achieve these flows. This is not an issue with many large petroleum facilities, but could be a challenge in some municipal markets.
Another area that is embracing high volume pumping is the maritime industry. Many of our boat manufacturers are ordering very high volume pumps and reporting extraordinary results. In our testroom, we need to operate from a lift condition and are therefore limited to about 3500 GPM (13,250 LPM). These vessels operate with no lift requirements and achieve much higher reported flows. Our latest sale involves a 1000 HP (750 KW) engine. We look forward to seeing what this will do for performance. I’m expecting flows in excess of 4000 GPM (16,000 LPM) and for vessels, unlike industrial truck ratings, this would be at 150 psi (10 bar). They certainly have the power, unless they need to reserve a lot more than I think they will for propulsion and maneuvering. These vessels are being furnished by MetalCraft Marine out of Canada to Tacoma, Washington and will be used for firefighting, or that is their intended purpose. My cynical colleague, Kevin O’Sullivan, suggests that these are more likely to be used for photo opportunities and to impress the mayor. That said, there are a lot of structures and other large vessels in many harbors that could benefit from high volume pumping.
Another area we’ve entered that needs super high volumes is the petroleum (shale) fracturing industry. We don’t supply the pumps that do the actual fracturing, but rather supply the pumps for water supply to feed those pumps. Although this isn’t an actual fire fighting application, there are a lot of similarities, and a few dissimilarities. These fracking feed lines, as they are known, can be several miles long, perhaps up to 50 miles (80 KM). This requires staging several pumps in relay to complete the entire chain of pumps and hoses.
The location where our pumps eventually discharge is a bulk water storage facility near to the actual well location. Much like the fire industry, reliability is highly prized. Once fracking operations have commenced, they must be continued until completed or the well must be capped. Such a disruption carries an enormous expense. This daisy chain of pumps need to be able to communicate with each other so that they can detect a disruption in the flow rate that requires some intervention. As noted, there is a short period of time to correct any complications. Our ability to coordinate communication between units, and to the command post, has also shown useful in military operations to move fuel over long distances, though the US military has not been interested in so high of flow rates. The experience we’ve gained in telemetrics and telematics may be useful in the future of firefighting, as vehicles can know the location of other vehicles and communicate operating status for smoother operations.
The high flow rates of the new pumps on the market require the builder or procurement officer to carefully consider the entire system. Is there truly a need for such high flow performance? How will it be fed and discharged? Is there sufficient power available for such operations? While a single high volume pump sports many advantages, it also requires careful study on the front end.
While there are instances where high volume pumping is worthwhile, or even plainly needed, smaller pumps shouldn’t be ruled out. The Red Rhino vehicles being produced in Singapore are a great example, where a small 500 GPM (2000 LPM) pump equipped with a compressed air foam system (CAFS) is being installed on a small, maneuverable vehicle for highly effective first attack. It is good to know that large volume pumps are now available, but it is not going to eliminate the need for smaller pumps.
One caveat to consider with high volume pumps is that they are not well suited to smaller flow rates. When a pump is designed for high flow rates, it should be operated at those rates. Using a 3000 GPM (12,000 LPM) pump to fight a 10 GPM dumpster fire is very hard on the pump, much harder than if a 500 GPM (2000 LPM) pump were being used for the same situation. Pumps work best when operated near their best efficiency point, and the further away from that one gets, the more trouble and wear there can be from operations, from flow vibration issues to overheating or cavitation damage.
Darley, and most other pump manufacturers, offer a wide variety of capacity and pressure ratings to suit many different applications – high volume pumping being just one.
I think the days of Clarence Saylor saying that he just wants the highest capacity pump he can get are long gone – a lot more study is required to take it to this next level.
For more information, go to www.darley.com