Knowledge and Safety the Keys to Successful Vacuum Truck Performance
If you attend a drag race, do you walk down from the stands, climb behind the wheel and run a top-level dragster down a ¼ mile straightaway in 4 or 5 seconds? Not likely, and certainly not without proper training about the powerful machine you are operating. Yet something similar happens everyday as vacuum truck operators man high-performance trucks, sometimes with limited knowledge.
Why is it that two operators can perform the same job with the same truck, same age and style and achieve two very different results? Chances are that only one of the operators is making best use of his equipment under the proper conditions and in the safest manner to maximize what the truck can do. That operator is saving his company time and money with greater efficiency.
Most truck operators do not have degrees in physics, nor should they. However, unless some fairly basic principles of physics are understood, trucks cannot perform at peak efficiency and the operator may put himself in very real physical danger.
Following are a few key points to keep in mind. It is not all you need to know, but they are several things I stress when talking to vacuum truck operators.
- Diameter size of the hose is very important.
Vacuum operators need to understand the importance of changing from one hose size to another and the impact of their decisions. Just how much impact can a slight change in diameter make? Look at the difference between a ¼" hose and a 3/8" hose.
In seminars, I connect each hose to a mustard jar and see how quickly the contents of the jar are emptied. You might think since the 3/8" hose is half again as large as the ¼", it would vacuum the contents at a 50% faster rate. Instead, contents are removed from the jar nine times faster! The jar with the larger hose is empty almost before the other has started.
- Hose diameter is also paramount in getting the most out of your truck.
Changing hose diameters in the middle of the job is not only inefficient it can be dangerous.
Start off with an 8" hose that the operator runs 100 feet and then change to a 4" hose. The volume at the start of the 4" hose is deafening. The truck is being asked to suction x amount of air designed to go into 8" at full throttle, though only through a 4" opening. The material flies through the hose at 4". Then when it hits the 8" section the power is reduced and material clogs up the hose. This severely impacts the air stream where the two sides meet and is destructive to your equipment.
- Performance decreases when friction is lost.
Hold a 7" inch hose with a ¼" diameter to your mouth and try to blow through it. Not difficult. Then try to do the same with a 7-foot hose. Your eyes will probably bug out trying to push air through to the other side. This gives you some idea of how hard your machine has to work.
- Smooth bore hoses almost always work better.
An advanced drainage system hose is very rough inside, almost like a corrugated material. An operator can get by with a drainage system hose on a short job, but on a longer and tougher job a smooth bore hose is necessary.
Safety is an issue as equal or more important than vacuum truck operation. Unfortunately, I see many of the same mistakes and same problems today as six or seven years ago, especially with new operators. Here are a few safety points to keep in mind when on the job:
- The tank is a confined space.
An operator may be handling toxic chemicals. If he enters the tank to make a repair, he might be overcome by fumes. There is only one way in and one way out when dealing with a confined space. Don't enter a tank when there are chemicals inside.
- An inline "T" and vacuum release can help ensure safety.
There are three release areas available with a truck, including a remote release or a manual release near the truck itself and an inline "T."
The larger the diameter of the hose, the bigger the force you have. If a 27" hose gets stuck to your body it can be fatal. An inline "T" is the mechanical device placed in the hose that kills the vacuum in the hose.
Nearly every injury in our industry occurs because those devices aren't working or aren't operative. If all 3 are working, you won't have injuries.
- Always ground the truck.
This is important for any product an operator uses. You might be sucking grain dust or something that might trigger a dust explosion. In fact, an air mover should never be used on anything being removed with a temperature flash point of 140 degrees or less. That is an industry standard.
- Wet and dry material should never be mixed.
In most cases, an operator does not know the chemical reaction if wet and dry materials are mixed.
In classroom settings, I test water and Alka Seltzer. I fill a jar with water and add eight tablets of Alka Seltzer. It blew the jar apart. There was nowhere for the pressure to escape. Who knows what might happen if a cubic yard of Alka Seltzer entered a full tank - or any other wet and dry combination?
The only exception is where a neutralizing acid might be used after a spill. A known chemical like bicarbonate of soda might be used with acid. In that case the operator has the knowledge to work safely.
Vacuum trucks are powerful enough to give an operator a false sense of security. They are so forgiving performance-wise, even when not used properly. But ultimate performance relates to how careful an operator is. Knowledge of your truck and common safety measures will aid performance.
Phil Stein of Guzzler Manufacturing presented his "Vacumm Truck Operators' Training Preview" at the 2002 Pumper and Cleaner Environmental Expo. He also teaches the seminar across North America approximately 10 times each year.