[Ken Wainwright]

When using my portable, I give an extra drying pass to achieve maximum recovery and to enhance the drying time of the carpet. Standard practice, most techs. do it.

On truckmounts, the air pump uses a different law of physics to our tiddly little 3 stagers. From what I'm told, these air pumps perform better with much higher volumes of water than portables. They don't work very well with small volumes of water. This is one reason for having bigger water pumps. My question is this: As a truckmount is most efficient when using larger volumes of water, is an extra drying pass of benefit? If so, why?

Safe and happy cleaning:)
Ken

[Glynn]

Of course it is Ken.
Before I sold off my last portable, I did tests
like this:
clean e.g. 80/20 twist with 2 vac portable including 1 dry pass at a moderate speed (not fast) the visible amount of recovered water in the see flow was nil(ish), then 1 dry pass with the TM, result a substantial extra water recovery.
The portable uses as we all know twin motors, the TM uses positive displacement blower. They both produce lift and air flow CFM.
However since the TM has more of BOTH properties it stands to reason that it has to be better. You can use a TM for dry vaccing as well, and it is very powerful, using it like this really require a dust downer, only to protect the blower etc. My TM for example has a 31HP engine, a portable is restricted to drawing 3HP off the mains !.
Hope this helps,
Regards
Glynn.