In the Judson rule book of truckmount designs; rule number 8 is that you NEVER bypass back to the pump inlet.
I will explain why...During bypass, the pump will overheat quickly. Relying on a thermal relief valve to keep the pump from burning up, and having the valve there at all when not necessary is just one more thing to break.
The pump cannot prime itself. In other words, if there is air in the pump, it just returns it to the pump inlet. This can cause the pump to run in a semi-cavitating state.
By using a small float tank, this allows the pump to bypass a volume of water like 4 gallons. This tank constantly primes the system, because the bubbles just float to the surface of the water.
By having a float tank, you are able to lay the wand down for a very long time without any heating issues. It allows the pump to pump cold water and the regulator to operate with cold water. This extends the life of the pump and the regulator.
I am now going to address the issue of chemical injection design. There is only one way to have a chemical injection system on a truckmount. This system has been on the Judson TNT since 1973 and is the most proven, trouble-free system on the market.
The TNT chemical injection system is exactly as Greenie described. It slightly starves the pump for water and the pump draws the chemical. Remember; this system is the most proven, trouble-free chemical system in the world. That's why this is the only way to do it. I absolutely see no reason to try to reinvent the wheel here.
I would now like to address the issue of water rinse versus rinsing agent. Water is different all over the U.S. Some water is heavy in metals, some water is heavy in minerals. Some water is harder than others. For example, have you ever gone to the beach where the water is hard and taken a shower? It seems like you can never get rinsed off!
This is why it is better to use a water conditioning agent to rinse with. Water softeners break down the surface tension. Heat also breaks down the surface tension. This makes the water wet faster. Seeing the water is coming out of the jet and in a split second is being vacuumed up, it is very important that the surface tension is broken down as much as possible.
Surface tension is not the only factor in a rinsing agent. Do you remember when I mentioned about taking a shower in hard water; how it is hard to rinse off? Another reason that it is this way is minerals in the water. The Judson soap-free O2 rinsing agent, is heavily kelated. This binds the minerals in the water and allows you to rinse the carpet more effectively.
The Judson O2 rinse has some other advantages. It brightens the carpet as it drys; it deals with wicking issues as it dries; it has a drying agent that accelerates the drying of the carpet expecially if you use an air mover.
It also has an additave called sodium borate that has high disinfectant properties. As a result, it assists in deodorization of the carpet, versus just masking odors with fragrance.
You should use the Judson soap-free O2 neutral rinse no matter what pre-srpay you use.
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