How to Use Portable Pumps And Be Happy With Them
The Volunteers Corner
Just about every fire department, no matter how small, has at least one portable pump.
The three basic uses for portable pumps are supplying water directly to one or two hand lines for fighting fire, supplying water to an automotive fire pumper, and dewatering cellars, pits and other places where unwanted water has collected.
The use of portable pumps has serious limitations when used to directly supply hand lines, although their use in this manner can be expedient when the fire and the static water source (pond, brook, etc.) are close to each other and a motorized pumper cannot get within reasonable distance of either the water or the fire.
Pumping capacity: The limitations on the use of hand lines off portable pumps is governed by the capacity and maximum pressure of the portable pump. In discussing “portable pumps,” we are limiting the definition to those pumps which two men can carry. In this discussion, we will not consider pumps of larger capacity that are so heavy they have to be mounted on a one or two-axle trailer.
The rated capacity of portable pumps can be disillusioning unless you know that portable pumps are rated for the flow of water at the pump discharge. To check the capacity of your portable pump under practical fire conditions, position it for drafting at as close to zero lift as possible. Run one length of 2 ½ or 3-inch hose from the pump discharge to an automotive pumper inlet. Also connect a 2 ½-inch hand line with a 1-inch straight tip to a pumper discharge.
Now start the portable pump and supply water to the automotive pumper. Ideally, there should be level ground between the two pumps, but a little rise will not matter that much as far as back pressure is concerned. Actually, it will probably more closely approximate your average fireground conditions.
With water flowing through the hand line, increase the pumper engine speed until the intake gage pressure flirts with zero, indicating that you are pumping all the water being received from the portable pump. Squeezing the supply line from the portable pump also will give you an indication of full use of water from the portable. After determining the nozzle pressure with a pitot gage, you can translate that pressure into gpm. This figure is a reasonably satisfactory determination of the useful pumping capacity of the pump—not the rated capacity.
Looking at capacity: Remember, you will be able to use only the flow that a portable pump provides for use on the fireground. You can’t use a portable’s rated capacity when that gpm cannot be delivered to the fireground because of friction losses in hose lines. The deliverable capacity of a portable pump is less than its rated capacity, but you can learn to live with the volume of water the portable can supply to your automotive pumper through the supply line lengths that you most frequently use.
Portable pumps are made in three basic types. One is designed to produce large volume with relatively low pressure, another to produce small volume with relatively high pressure, and the third is designed for medium volume and medium pressure.
The large volume, low pressure pump is best for supplying automotive pumpers because the only objective is to get as much water as possible to the large pumper. With whatever flow of water the automotive pumper receives, the pump can increase the pressure to any fireground requirement— within the limits of the amount of water received. In other words, don’t expect a pumper to supply a 250-gpm hand line with only 200 gpm from a portable pump.
Use of portables: When you want a portable pump mostly to supply water to an automotive pumper, obviously you want a high volume, low pressure portable. On the other hand, if you use a portable mostly for supplying hand lines directly, either the high pressure-low volume, or the medium pressure and volume pump is the one to use.
If a pumper has two 2 1/2-inch suction intakes, two portables can be used to supply the pumper. A reducer also can be used on a large suction intake to provide a connection for a supply line from a second portable. You also can put a clapper Siamese on a 2 ½-inch suction inlet. When it is necessary to obtain a larger water supply through the use of several portable pumps, put the supply lines from these portables into a portable reservoir from which the automotive pumper can draft.
When dewatering after a fire or pumping out flooded cellars and other areas, portable pumps should be used to avoid damage to the much more expensive pumps on fire apparatus. It is surprising how much damaging junk can pass into an apparatus pump through both the suction hose strainer and the pump suction inlet strainer. Not only are repairs to portable pumps less costly than those to apparatus pumps, but also a portable pump that is out of service is a relatively minor problem compared to an automotive pumper being out of service.
You can avoid many headaches with portable pumps if you operate them on a regular schedule in the station. The portables can be run for a short time once a week—along with portable generators and power saws. In some paid departments, this is accomplished by having each shift run this equipment each time a shift starts its day tours.
A fresh gasoline supply and clean spark plugs with properly adjusted gaps are two other things that will ensure operation of portables when they are needed.