How Do Vacuum Pumps Work?

This pressure differential and the surface area of the cup or pad define the attraction force so that even a large item can be lifted.

There are several different types of vacuum pumps for industrial use; the operation and basic working principles of these are the same. They consist of a device whose purpose is to extract molecules of gas or air from a vacuum chamber. This reduces the pressure inside the chamber and makes it increasingly difficult to suck the molecules out. Industrial vacuum pumps are designed to cope with a large range of pressures, so they can more easily overcome this problem.

How do you create a vacuum?

A vacuum is usually created by using either pumps or generators. Pumps also work by generating a vacuum. Vacuum pumps can be used like conventional pumps to transfer liquids from one place to another, but are much more useful in manufacturing processes or engineering. 

A vacuum generator creates a vacuum using the Venturi system, where air passes through a tube with a restriction that causes a low-pressure area. Although vacuum generators are static with no moving parts, they require a constant flow of air to create the vacuum grip. Vacuum generators also use solenoid valves to turn systems on and off, but centralised systems of this type still need valves at the suction cups or pads. 

These valves open and close the path of the vacuum and can activate either one or multiple suction points in a materials handling bed. Newer technology deploys sensors to actuate only selected suction points if items are not identical or have a complicated shape. 

A vacuum pump creates differential pressure in a similar way to a compressor creating compressed air, by pumping the air molecules out of a sealed chamber. They’re not as common as vacuum generators but are an easy and efficient means of handling materials.

Types Of Vacuum Pumps

Vacuum pumps can generally be split into either wet (oil-lubricated) or dry (without oil), depending on whether the lubricant forms part of the air compression process. There’s a wide choice of vacuum pump designs, including piston-type, rotary vane, side-channel, liquid ring and displacement types. In addition to these, the four most commonly used types are:

Diaphragm Vacuum Pumps

This type of pump has two mechanical diaphragms, which increase and decrease pressure by moving in and out – or backwards and forwards – with a valve to prevent liquid backflow. Diaphragm pumps are widely used in industry, as they have a reputation for accuracy.

Positive Displacement Vacuum Pumps

This type of pump confines a precise amount of air or gas in a chamber and compresses it. They provide a moderate, low-power but steady flow of suction through an intake point with an expanding cavity leading to a discharge point with a decreasing cavity. 

Momentum Transfer Vacuum Pumps

Sometimes called kinetic pumps, this high-pressure type of pump forces gas or air from the intake to the outlet via a rotating component. A low-pressure region develops into a vacuum and is sealed by a powerful valve. Momentum transfer pumps work by either regenerative or centrifugal force. The centrifuge type propels fluids forcibly through the device, while the regenerative, peripheral or turbine type recirculates liquid inside to pump up the pressure.

Entrapment Vacuum Pumps

This type, also called trapping or capture pumps, comprises refrigerated devices that are good for storing air or gas for use later. They induce air molecules to condense by cooling them in a confined space and then removing the resulting liquid. Condensation can also be induced using electrical fields.

Safe Operation Of Vacuum Pumps

Vacuum pumps are powerful industrial components and can be dangerous. Potential health and safety hazards include:

• Accidental exposure to moving parts causing injury

• Faulty wiring causes electric shocks and maybe fire

• Overheating or other malfunctions causing a fire

• Inadequate ventilation leads to a build-up of toxic fumes

• Incorrect use causes spillage of contaminated pump oil

Health and safety is always a priority in the workplace, so you need to be sure you understand thoroughly how the vacuum pump works before you put it into operation. Some important ways to enhance pump safety include:

• Only operate pumps in properly ventilated areas – if possible in a ventilation cabinet

• Make sure pump exhausts or outlets are always free from obstruction

• Wear appropriate PPE

• Ensure appropriate belt guards are fitted

• Check tubing is fit for use and fully compatible with the pump

• Check all cabling and switches for potential faults

• Make sure there aren’t any combustible materials in the surrounding area

• Monitor oil levels and top up or change the oil as required

• Dispose of any discarded oil safely and in the proper manner

• If any faults occur, use a spill tray to catch leakage   

When Would You Use A Vacuum Pump?

You can use vacuum pumps for handling or transferring bulk materials, in analytic equipment such as spectrometers, electron microscopes and radiotherapy systems, as well as in gyroscopes for flight instrumentation, lighting and air conditioning systems and dairy equipment.

It’s important always to match a vacuum pump carefully to your particular requirements. You can choose from compact all-in-one units or large-scale central vacuum systems, depending on your business needs. You’ll need to decide what brand of vacuum pump to purchase, as some manufacturers specialise in particular types.

Specifying your vacuum pump includes not only its intended application and performance requirements but also choosing the right type and size of pump for your needs. Specific instructions on use of your particular product should be provided by the manufacturer, but it helps if you understand the basic properties of a vacuum and the pump’s working principles.