FAQ – A Primer on Vacuums
There are three important things to look for in a vacuum: CFM, static lift and filtration.
CFM is an abbreviation for cubic feet per minute. This is a measure of the volume of air the vacuum is moving. Most vacuums move enough air to work with point of origin dust collectors…at least for a few minutes. But on weak vacuums, when the filters start to load up, the CFM soon begins to drop.
Whereas CFM measures the volume of air moved, static lift measures the ability to keep the air moving under a load. Static lift is measured in inches. It can be equated to torque on a motor. If a vacuum has 80” of lift, it means it can lift a column of water 80” off the ground.
When a filter is loaded up with fine dust, it becomes more difficult to pull air through the pores. A vacuum that delivers 120CFM with 90” of lift will continue to pull a large volume of air through the filter whereas a vacuum that delivers 120CFM with 40” of lift will tend to see a substantial drop in the CFM pulled through the hose. This will result in a loss of efficiency for the dust collector.
There are many types of good filtration systems. They run from pulse type back flush systems to paper and plastic disposable bag type filters. Often machines use a combination of filter types to deliver the optimum performance. The filter is the heart of a vacuum and it is essential it is correctly specified for the application.
In addition to CFM, lift and filtration, the operator should also be aware of how the vacuum is constructed and the true power of the motor.
A bypass motor is usually the best design for site use. With this design, the dust is not brought through the motor by the cooling air, thereby prolonging motor life, particularly the brushes and armature. If the vacuum is not equipped with a bypass motor, be sure it has a secondary filter downstream of the disposable filter to further protect the motor in case the disposable bag filter fails.
Lastly, be sure you know how to read the true power of the motor. Many vacuums will not deliver the performance claimed. Dyson have spent a small fortune trying to have EU laws changed so that advertised performance is factual and represents actual site operation rather than laboratory conditions.
The Dust Muzzles, Crack Chasers and Saw Muzzle for the 7” worm drive saws will be very efficient if they have a steady 80 CFM of airflow through the exhaust port. This airflow can be well maintained if the vacuum has at least 80” of static lift.
The Saw Muzzle GP for the gas-powered saws runs best with a steady 110 CFM and at least 80” of static lift.
The TV50 is a very strong, industrial vacuum that is capable of effective dust control on most angle grinders, sanders and polishers.