How Do I Fill a Water Truck?
- The most important step in filling a water truck is proper positioning. The manhole to fill a water truck is located on the top of the tank, and when the truck is filled, water comes down from a valve in the ceiling. As such, it's important that a driver position the manhole directly beneath the valve. This may require several adjustments if the driver is alone, but if there is someone else around he can give hand signals or shout out when to stop so that the water truck is properly positioned. To check the position, the driver should climb the side of the truck and check the alignment of the manhole and the fill valve in the ceiling.
- The filling process actually consists of several different steps. The fill valve in the ceiling should be opened slowly, and the water should be watched to make sure that it's all going into the manhole in the water truck. There will be a water gauge on the side of the water truck, and it should be watched throughout the filling process. When the fill level reaches about 3/4 full, then it's time to slowly close the fill valve. Ideally this should bring the water level in the truck to just below the roof line of the cistern.
The Hammer Effect
- It's important that those who are going to be filling a water truck learn about "the hammer effect" that water can have. This means that when a valve is open too quickly, water will move too fast and could damage what it hits when it comes out (in this case the water truck, which is an expensive piece of equipment). The same thing occurs when a water valve is closed too quickly. The water flow, if the valve is closed too quickly, will result in the water striking like a hammer against the now closed valve and increasing the pressure within the pipe. This can lead to a burst pipe, or a damaged valve if it happens too often, or with too much force.