The primary shut-off valve is one of the most important parts of vacuum truck tanks; it is the main protection point to prevent fluid or material from entering the pumps. It is vital to know the location and complete functioning of this valve; it must be monitored and kept in clean, working order in order to keep the whole vacuum system operating properly. Without it, there could very well be an expensive repair bill when the pumps fail to work.
Parts and Function
The main shut-off valve on a vacuum truck is located along the top of the tank; its purpose is to close off the vacuum to the pump before the tank overfills and fluid or other material is able to enter the pump. The primary parts include: a hole in the top of the tank that connects to the pump via a tube; a wire cage surrounding the hole; and a steel ball sitting in the wire cage.
When the tank fills to its limit and contents reach the shut-off valve, the ball is lifted into the cage until it is sucked over the hole. The ball then seats and remains, preventing the passage of anything from the tank into the pumps; such action could damage the pumps or make them susceptible to corrosion from contact with any liquid. It is a very simple process that provides an important protective measure.
The primary shut-off valve on any vacuum truck tank is a very simple concept; it does need to be well maintained and its condition checked frequently. The main problem that happens with these parts is that the metal cage holding the ball can corrode and break open, dropping the ball into the bottom of the tank. If that happens, the shut-off is nonfunctional and the pump is in danger. To prevent this from happening, it is important to check the primary shut-off valve every day when cleaning the tank to be sure there is not any excessive corrosion or any appearance that it may be breaking. If it seems in good condition, keeping the valve, ball and cage clean and free of debris is critical for everything to work properly.
Repair or Replacement
If the mechanism is beginning to show wear, corrosion, or any other evidence of breakage, it should be replaced. It is welded in, so the vacuum truck will have to be out of service for a day; however, knowing ahead of time about a repair is the best way to get it done when it is convenient and not an emergency. If only the cage is corroding, it can be removed and a new one welded in place. If the whole valve itself seems in bad shape, the entire part including the cage, ball and valve can be removed and replaced.
Although stainless steel primary valves are available, they are expensive. Even if vacuum trucks go through more than one valve replacement in a lifetime, it is still common to simply commit to regular monitoring and cleaning of the valve and replacement when necessary. Commitment to this effort is essential yet shouldn’t be an usual effort as cleaning and inspecting vacuum truck tanks should already be happening. Monitoring the primary cut-of value is a simple addition to the daily routine – and the best choice to make!