by Tony » Mon Oct 27, 2008 11:57 am
Vacuum motors are a pretty good way to get started building a flow bench, but they do have some disadvantages. The biggest probably being high power consumption, high noise level, and the relatively short life of the high rpm brush type motors.
If you are planning something from the start to have well above average flow or pressure capability, a single large diameter industrial blower (or supercharger) will very likely be more power efficient, and produce vastly less noise, and it should run for years without any motor fires or explosions.
When building your bench, realise it has to withstand considerable air pressure over some very large areas. The forces involved can easily reach many thousands of pounds, so bursting or implosion of the main bench structure is always a risk under blocked flow conditions.
That is another disadvantage of vacuum motors. A large diameter industrial blower will put out fairly constant discharge pressure, even with completely blocked flow. Some two stage vacuum motors can spike to well over 120 inches with completely blocked flow, and that could burst your bench.
It is always much easier for the structure to withstand high vacuum than high positive internal pressure. Leaks are less likely under vacuum, as all the joints compress. My own preferred method of bench construction these days, is a welded steel angle frame, with MDF panels bolted to the outside. If I ever get around to building yet another bench, I would do it this way again without hesitation.
Also known as the infamous "Warpspeed" on some other Forums.