Basic Operation

All vacuum cleaners operate on the same basic principle which by lowering air pressure a vacuum is created. Air pressure is lowered by an electric motor-powered fan that sucks air into the cleaner's intake port or hose. The vacuum effect pulls in air and particles into the intake port and is held within the cleaner's containment system, usually in the form of a canister or bag. The air intake is filtered as it passes through the containment system and exits through the fans exhaust port.

Wet/Dry Systems for Workshops

Workshops present many challenges that an ordinary household vacuum cleaner would not be able to handle effectively. Liquid spills or large particles, such as sawdust, cannot be contained well enough by the standard bag system. Shop vacuums, also known as wet/dry vacuums, are designed to better contain these elements without fouling the fan motor or clogging vacuum bags.

The fan motor is mounted over a bucket-type canister and pulls air in through the intake. The flow of air through the narrow intake hose slows down as it enters the wider bucket, diminishing the vacuum effect to allow liquid and particles to drop into the bucket without entering the fan. The bucket design allows the user to remove the lid and empty the contents when needed.


Shop vacuums use several different ratings to describe performance details. Horsepower reflects the peak power output of the motor. However, horsepower ratings are typically outside the vacuum cleaners normal operating range and may not indicate actual air performance. Sealed Pressure (SP) is measured by how far a vacuum motor will lift a column of water within a sealed a glass tube. Maximum suction pressure is obtained at zero air flow with pressure decreasing as air flow increases. Cubic Feet Per Minute (CFM) measures the quantity of air moved by the vacuum motor while in operation. CFM can be affected by clogged or dirty filters, which reduce the flow of air and decrease suction.