BY BRIAN MOLENAAR AND CHRIS DENNIS
The curriculum for new pump operators in Wisconsin requires students to spend considerable time developing pumping skills for the practical skills evaluation in addition to the classroom instruction. As in most volunteer fire departments, it is sometimes difficult to gather the necessary personnel to operate handlines to simulate fireground pumping conditions. To address this situation, we developed a device for simulating pumping conditions that requires only two firefighters.
The pumping simulator is a U-shaped device that is attached to the hose at one end; the other end is submerged in a folding tank.
One end of the U-shaped device attaches at a 90° angle to the hoseline. At the other side of the “U,” a one-foot length of pipe is attached at a 90° degree angle and terminates in a T-shaped discharge (photos, 1, 2).
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To construct the device, we used Schedule 40 PVC piping with solvent welded fittings, PVC National Pipe Thread (NPT) nipples, and a hex adapter to go from NPT to National Hose Thread (NHT). The U-shaped piping is easily attached to a portable folding tank frame with two wire ties, one near the top and one near the bottom. The piping’s pressure rating of 280 psi is adequate to develop pump pressures that simulate those of handline operations.
The “T” on the discharge end eliminates almost all reaction forces, which are divided equally on each side of the “T.” Although we had drilled a small hole in the end of the “T” opposite the discharge flow to create a small amount of backward reaction pressure, we found this was unnecessary if the device was secured to the folding tank supports. Hose placement affected the movement of the device more than the actual flow of water.
Using a folding tank provides the flexibility of using the engine in drafting or hydrant operations. During drafting, we recycled the water in the portable tank. Typical simulations practiced during drafting operations included loss of suction and pump recovery. The instructor would simulate air leaks by lifting the suction line to allow air in, causing a temporary loss of prime.
During hydrant operations, we allowed the folding tank to overflow. When our device was connected to a 100-foot, 1¾-inch line, we were able to flow 200 gpm at 175 psi. This worked well in obtaining the different pressures and flows. For reduced water flows, we simply increased the length of the hose to create more friction loss in the line.
We also found that when pump temperatures are a concern during drafting operations, this device can easily be attached to a hoseline and left in the folding tank to circulate enough water to keep the pump cool. We have used this device during live-fire evolutions with our engine acting as a reserve water source. When using the device as a recirculation line, we found that the water temperature increased only minimally during a three-hour standby period. Another benefit of the recirculation line was that it was easier to maintain the pump prime during extended scene times with little water usage or waste.
Initially, we intended to create a larger manifold device that would accept multiple connections and also function as a jet siphon. However, this idea was abandoned because the cost and the overall size of such a device would make it less portable. The current design is much simpler, still performs dual functions, and is much more portable. We were concerned about turbulence resulting from discharging water into the folding tank, which we believed would cause drafting problems. However, we found that once the device was flushed of air, the water in the folding tank remained relatively calm. Also, we discovered that by placing the devices in the tank on the side opposite the pump suction, the water was even less turbulent. This arrangement allowed for a more efficient use of space with the hoselays.
Some members of our department were concerned that the device might come apart during pumping operations. We performed a pressure test using a 100-foot section of 1 3/4/-inch hose with the line pressurized to 250 psi without failure. Although this is not a working pressure we commonly encounter, we were confident that the device could withstand higher operating pressures, and it addressed members’ concerns.
As with any hydraulic device, we strongly recommend that materials selected for a similar device be rated for the pumping pressures encountered. Also, the device should be thoroughly inspected for signs of fatigue or failure before each use.
We found this device extremely helpful in refining our pump operating skills and hope that others will benefit from building a similar device.
BRIAN MOLENAAR is a firefighter, an EMT-I, and a motorized pump operator with the McFarland (WI) Fire Department.
CHRIS DENNIS is a lieutenant, an EMT-I, and a motorized pump operator with the McFarland (WI) Fire Department.
