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Tel:  03 9764 8633
Fax: 03 9764 8979
Electron Vacuum Systems Pty Ltd
48 Jellico Drive Scoresby, Victoria.
Australia 3179

Vacuum Technology


While browsing through this web site and in general research of ducted vacuum systems, you may come across some wording you don't fully understand. These ducted vacuum definitions will help you better understand some of the terminology used within the ducted vacuum industry.

ABS Plastic

A high impact plastic polymer made of Acrylonitrile, Butadiene and Styrene. Acrylonitrile brings heat stability and surface hardness, butadiene adds toughness and impact resistance, and styrene provides rigidity. This combination provides many, many years of maintenance free use and it will not corrode or rust. It also dampens the natural sound made by an electric vacuum motor. Electron power units are constructed from ABS and feature a lifetime warranty on the vacuum's canister.


When a ducted vacuum cleaner is started, it creates a vacuum or an area of low pressure. Outside air rushes in to fill this vacuum. This rush of air or "Airflow" is controlled and directed for maximum cleaning efficiency. Airflow can be measured by the term litres per second.

Air Pressure

The air around us constantly exerts a pressure of about 400 inches of water. That means that every exposed surface has the equivalent of 400 inches of water pushing on the surface. A vacuum cleaner doesn't actually create a vacuum, but it does lower air pressure inside the vacuum unit. Since the outside air is at normal pressure it rushes inward in a controlled airflow which creates the cleaning effect.

Air Watts

Ducted Vacuums are measured by Airflow and Vacuum. Each of these measurements are in themselves inadequate because a vacuum is working somewhere in between these opposite maximums. A vacuum is not operating with sealed suction or at a 50mm vacuum opening but somewhere in between. When you read Airflow and Vacuum specifications of a vacuum, remember you are reading their maximum values. These values are never at that measurement at the same time in an operating vacuum. Air watts is a calculated measurement taking into account both the Airflow and Vacuum in real time at the operating end of the vacuum hose, tool, or brush. You have to know the curve created by both values as the opening changes from zero to 50mm. Somewhere along this curve the calculation for air watts will maximize. The peak is around the 19mm orifice and this orifice opening is usually where you will find where most vacuum cleaning tool’s air intake will be.

Amperage (Amps)

Represents the amount of electrical current used by the ducted vacuum motor during use. Ampere is to electricity, as litre is to water; a measure of quantity.


The part of the ducted vacuum motor that rotates, and on the end of which vacuum fans are mounted. A quality armature is mounted on ball bearings, and protected from incoming vacuum air that has been heated and dirtied.

Bypass Cooling

A separate stream of air that cools the motor, different from the air that draws in dirt from the home. In a bypass motor, air being vacuumed does not actually flow through the electrical components of the motor. Normally these motors have a separate fan to provide cooling air to the motor.

Central Vacuum

Ducted Vacuum Systems are also called Central Vacuums and Built-In Vacuums.

Cyclonic Action

Cyclonic action describes the natural action found in a tornado. In a ducted vacuum with cyclonic filtration, the air carrying the dust and debris moves through a tornado action. The air swirls downward in a cone-shaped pattern. At the bottom of the cone, it starts swirling upward again, inside the downward cone. Thus this is sometimes called a 'reverse' tornado action or 'dual cyclonic action'. The vast majority of the debris separates from the air steam as air reaches the bottom of the swirl, and is deposited in the dirt container. Only a small fraction remains in the air, to be removed by the secondary, cartridge-type filter or other filter type.


While decibels are a measurement of a sound volume, the average human ear can perceive a significant difference in volume between 5 decibels. The lower the decibels level, the quieter the unit.


The fan is the combination of blades that spin around to create the airflow to produce the vacuuming action. A ducted vacuum motor with two fans is called a 'two-stage' motor; if it has three fans it's 'three-stage' motor.

Flow Through discharge

In some less-expensive motors, the air drawn from the home flows right through the motor to cool it. Unfortunately this air is laden with the dust from the home which dirties and contaminates the motor. This air is also warmed by friction as it moves through hoses and piping, and is substantially warmer so it is less able to cool the motor. Thru-flow motors will overheat if they are run for long periods of time without adequate air flowing through the system.

l/s(litres per second)

A common unit of the measure of air moved by the vacuum fans. This measures the "volume" of air the motor is capable of moving and works in tandem with "Suction". Airflow can be a bit confusing however, since performance measurements are taken from the motor and do not factor any resistance found in a typical ducted vacuum system. Filtration, piping, hoses and accessories all restrict and reduce the amount of actual Airflow a system has. While Airflow is important to system performance, Suction or the "pulling of air" maintains the Airflow velocity necessary to sweep dirt and debris away at the hose end where vacuuming takes place.

Motor Brushes

The sliding contacts that provide electrical power between the stationary stator and the rotating armature of an electrical motor. Brushes are the most wearable part of an electric central vacuum motor, and should be replaced every few hundred hours or few years of operation.

Motor Speed

Measured in revolutions per minute (RPM).

Paper Filter Bag

A collection device for dust and debris.

PVC (Poly Vinyl Chloride)

A common plastic polymer that provides excellent appearance and longevity with good flame retardence at an attainable price. All of MD Manufacturing central vacuum fittings are made from virgin PVC.


This indicates the number of sets of fan blades in a central vacuum motor. Each fan - set of blades - increases the vacuum, or speed at which air is drawn through the system. The first fan starts air movement; the second increases it, and if there is a third fan it increases airflow still more.

Tangential by pass

Tangential bypass refers to the vacuum motor’s actual design. The design uses a separate fan for cooling the motors armature and stator (motors winding), the armature spins and the stator is stationary. Tangential bypass uses a series of impellers (fans) and shrouds to pull airflow through the motor and a special exhaust duct (called an exhaust horn) to port the exhaust out of the motor. The entire fan/shroud/horn assembly is separate from but connected to the motor. This design is widely accepted as the superior system for it's efficiency and reliability. Tangential bypass motors are often used in one of two sizes for central vacuums, 145mm or 183mm diameter and may have a series of one, two or three impeller (fan) blades referred to as motor stages. Bypass vacuum motors often have a lifespan of 25 plus years with little maintenance.


A measure of the electrical potential employed by a central vacuum motor. Typically, motors require common household current of 240 volts in Australia. Voltage is to electricity as pressure is to water; a measure of potential or driving force.


A total vacuum is the absence of everything, even air. Vacuum cleaners actually create a partial vacuum, or more accurately, an area of reduced air pressure, as air moves outward within the fan. Airflow is created as air with normal air pressure moves toward the area with the reduced air pressure.


This measures the suction strength of a ducted vacuum motor. Essentially, it tells how much "pull" or "lift" power the motor has. This measurement is always taken at its maximum value, the 0" inch orifice (sealed vacuum) where suction is at it's greatest. Since this measurement is taken from the 0" orifice, it is very misleading. This measurement does not take into account piping, hoses or accessories etc., thus giving a false measurement of power. Often referred to as Inches or Waterlift or Vacuum, Suction is vital to overall system performance since it is the "pull power" that maintains Airflow though the complex network of vacuum pipe, hose and accessories. While Airflow is necessary for a vacuum cleaner to work, suction creates the lift and velocity of air which sweeps dirt away. Waterlift is NOT a true measure of suction, however it is a form of measurement and part of the equation when measuring Air Watts. This is the most misleading measurement of suction power.



Quick Contact
Tel:  03 9764 8633
Fax: 03 9764 8979
Electron Vacuum Systems Pty Ltd
48 Jellico Drive Scoresby, Victoria.
Australia 3179