Back in the day — before the introduction of the large-diameter hose (LDH) — we would use two lines of hose to supply our trucks. One was a 2.5-inch and the other was a 3-inch, laid out simultaneously to the spud intakes of the truck.

We had a procedure of always putting hose clamps on each hose. Then, when the driver was ready, he would open the hose clamps and then the gate at the spud to get the incoming supply of water for the truck.

Those days are gone now since fire departments have moved to using LDH, either 4-inch or 5-inch. The advantage of using LDH is the significantly-reduced friction loss and the volume of water that can be transported through the hose line.

One of the most important things to remember when using LDH is that it is not a "pressure" hose like those used for firefighting attack lines — it is merely a "supply" line. So, to put things into perspective, we are moving a large volume of water.

At my former department, we used 5-inch hose for our supply lines. The 5-inch hose holds about one gallon of water per one foot of hose, and hose sections come in 100-foot lengths. Therefore, each section holds about 100 gallons.

Since one gallon of water weighs 8.36 pounds, one section of supply hose weighs 836 pounds. When this hose is filled with water, it is not getting moved! You will suffer some sort of injury if you attempt to move it, especially for one person.

Thus, planning where the line is being laid is crucial.

Vehicles that try to drive over it will get caught up on it, especially if driving over a coupling. Since the hose is difficult to move when filled with water, you need to leave access for other apparatus, such as aerial/ladder trucks to be able to spot in front of or at the corner of the building.

If the hose is right in the middle of the street, these trucks won't have access. It needs to be laid off to the side of the street as best as possible.

Now that we have some sort of perspective as to what LDH is and does, this is where the ball intake valve and pressure intake valve (BIV/PIV) come into play. These hose appliances allow us to control the "large" amounts of water flowing through these hoses.

Large amounts of water and their hydraulic forces can be dangerous. A good example is walking through a river or stream with flowing water, or at the beach when the riptides and currents are moving under the water. And as an extreme example, think about the destruction that occurs when a tsunami hits land.

The incoming volume of water cannot occur rapidly. If a BIV/PIV is not placed on the intake of the apparatus pump, the truck will get slammed with large volumes of water. Having no control of the pressure/volume will result in damage, either to the truck or individuals.

Remember, the intake going directly into the pump does not have a separate gate on it, unless you have specified a remotely operated one. That is why BIVs/PIVs are put in place, to allow drivers to control their supply line.

Hose clamps still come into play, even though I do not think anyone is still using them in their hose evolutions. They serve a purpose for when a hose line breaks, which brings up another point.

If a driver was initially pumping from the tank before getting a supply line, the first thing he/she needs to do once the supply is established is to fill the tank back up to full immediately. This way they have a backup water supply in case the supply hose gets damaged, gets run over, bursts or gets cut. A driver of a normal passenger vehicle can be inattentive/distracted or for any other reason may have an accident and take out your hydrant!

Practice, training and drilling need to occur to assure that operations are done safely — first and foremost to yourself, your crew and citizens in the immediate vicinity. Good luck and be safe!