Chapter 1 – The Basic Stuff
This is the basic information that most every buyer will prefer to have in front of them when they purchase an industrial vacuum. This stuff will help give you an idea of what to read through in order to make an educated choice as a buyer.
Chapter 2 – A different CFM
This is the lesson in “air flow” that’s eventually covered in just about every vacuum system sale. There is more confusion over the terms “SCFM”, “ICFM” and “ACFM” than any other topic in the wonderful world of compressed air. So, for the layman, here are a few definitions:
The system diagram beside shows three different points in both a vacuum and pressure type system. Note that the location of ICFM changes with pressure and vacuum applications Note that in a vacuum system, the volume of air expands (is rarified) as it travels toward the air pump inlet (and thus travelsfaster in a fixed size pipe). In the pressure system, air expandsin exactly the same way as it travels from the compression side of the air pump to the system end point. And as a final small note, the only difference between a vacuum producer (or exhauster) and a blower is the side of the process connection.
Chapter 3 – Let’s Discuss Pressure
This is a quick lesson in pressure and vacuum terminology. There are a few common pressure terms that need to be understood if you’re going to talk vacuum with those of us in the business. Here they are:
|W.G.||Water Gauge (plus a height dimension)|
|W.C.||Water Column or Column of Water|
|Inches H2O||Inches of Water (Column)|
|S.P.||Static Pressure (usually in inches)|
|Water Lift||Water Lift|
These are all the same thing. They can reference pressure or vacuum, but is normally associated with dust collector fan performance. In vacuum systems, it’s most often used when talking about pressure differential across a filter media.
Chapter 4 – The Dreaded @
Marketing is a competitive business, and there are always some vendors who feel the need to over-emphasize the positive things about their vacuums, and perhaps even to exaggerate beyond what their units can really do. Performance claims are often boastful for many types of products, but there are really a lot of extremes seen in the vacuum business. And you rarely hear about a unit’s limitations. Hey, every unit has some limitations. Here is your reality check!
Almost every vacuum company states their performance figures at either end of the performance spectrum, since those figures will always be the largest for each typical scale.
For example, when making claims about volume performance, many companies use what’s known as the “open condition volume”. This is the volume that is achieved by a vacuum producer when pulling 0 vacuum. They also use conditions you would only find at zero flow to make vacuum performance claims.
Combining those two figures is simply meaningless. It’s like measuring your car’s mileage while it’s running in your driveway. Worse than this are companies whose marketing copywriters get confused and use the two performance claims together, with the @ symbol.
Chapter 5 – Horsepower Stories
As we mentioned in our last section, marketers love to exaggerate their units’ productivity beyond reality. The retail vacuum business is likely one of the areas where the most grievous infractions occur. But if our customers have already tried shop vac units, we usually need to explain to them the ins and outs of horsepower – we’ll even explain it to people who already should know.
As you might know, you can easily find vacuums that state their horsepower with wide, bold numbers, like 5.0 Hp or even 6.0 Hp. But they still plug into standard 15 amp electrical outlets. What’s up with that? Turns out, if you read the really, really fine print, you’ll see something like “10A” on the nameplates.