One of the most frequent questions people ask about vacuums is “how do you know how strong a vacuum is?” A vacuum’s ‘strength’ has two parts to it: CFM and Water Lift
CFM Is Air Flow
Air flow is the volume of air moved through the vacuum. It is measured in vacuum specifications as CFM, or cubic feet per minute. The more air flow through a vacuum, the better. A common air flow measurement is 125 CFM. A very thorough guide to air flow, as well as how it is measured in different vacuums, can be found here.
Water Lift Is Suction
Suction is measured in terms of water lift, also known as static pressure. This measurement gets its name from the following experiment: if you put water in a vertical tube and put a vacuum hose on top, how many inches high will the vacuum pull the water? A common suction measurement is 85″.
A Good Vacuum Has Balanced Air Flow and Suction
Our HEPA Wet+Dry Vacuum comes in at 130 CFM and 103.6″ Water Lift.
Many vacuum buyers find themselves upset when the vacuum they purchase doesn’t perform as well as the store made it sound. This is often because the air flow and suction are not balanced. For example, a vacuum might have exceptional air flow, but if it has low suction, the vacuum will not pick up particulates well. On the contrary, a vacuum that has a good air flow rating and a good suction rating will perform highly.
We know that a good vacuum has a balanced CFM and water lift rating – so what do good numbers look like?
A strong air flow rating is around 125 CFM and higher. This is strong enough air flow to pick up most anything you may work with – including dust from 5″ or smaller grinders.
A strong water lift rating begins at least 80″. This is the point where the suction will be strong enough to produce desirable results.
When you go to the store, be sure to look at those two metrics: CFM and Water Lift (Static Pressure). They should be close to 125 CFM and 80″, respectively, or higher.
Connecting Vacuums Together
You can get good work out of a single vacuum alone – but what happens when you connect them? The effect on suction remains the same, yet the air flow is additive – combining two 125 CFM vacuums produces
250 CFM through a single hose. It can be of great advantage to combine two vacuums together for an exceptionally strong vacuum system that can easily be broken down for transport. We have a kit specifically for combining vacuums together.
If you would like to learn more about vacuum suction and how our products can increase the abilities of your vacuum system, give us a call at (435) 637-5885 to learn more!