Find the Right Air Compressor

Air Compressor Comparison Guide

Use the selector and comparison table below as an initial guide. It identifies the most suitable compressor category, while final machine selection should still be based on airflow, pressure, operating hours and site conditions.

Detailed Air Compressor Buying Guide

Use this detailed guide after browsing the categories or completing the selector. At Compressed Air Systems UK, we supply air compressors for workshops, manufacturing sites, commercial premises, specialist installations and mobile applications.

The range available through the Tanair Compressors website includes piston, rotary screw, vane, variable-speed, petrol, diesel, medical, dental and smoke ventilation compressor options.

What Information Is Needed to Select an Air Compressor?

Before choosing a compressor, gather as much information as possible about the application and existing system.

• Required airflow in CFM or litres per minute
• Required operating pressure in bar or PSI
• Number of tools or machines operating at the same time
• Daily and annual running hours
• Whether demand is steady or variable
• Available electrical supply
• Permitted noise level
• Available installation space and ventilation
• Required air quality and drying
• Expected future expansion

CFM, FAD and Displacement

Compressor airflow can be shown in several ways. Free air delivery, often abbreviated to FAD, represents the usable air delivered under stated conditions. Displacement is a theoretical figure and is normally higher than actual delivered airflow.

When comparing compressors, use comparable FAD figures wherever possible rather than selecting a machine from motor power or receiver size alone.

Operating Pressure

The compressor must provide enough pressure for the process after allowing for pressure losses through dryers, filters, regulators, pipework and hoses.

Running a compressor at a higher pressure than necessary increases energy use. The system should therefore be designed around the lowest practical pressure that still supports reliable operation.

Duty Cycle and Running Pattern

Duty cycle describes how long the compressor is intended to run compared with its rest period. Piston compressors are generally suited to intermittent use, while rotary screw and vane machines are better suited to longer daily running periods and continuous demand.

A compressor that is regularly operated beyond its intended duty can overheat, wear prematurely and require more frequent maintenance.

Piston Air Compressors

Piston compressors are a practical option for workshops, garages, maintenance areas and applications with intermittent demand.

They are often selected where:

• Air is used in short bursts
• Daily running hours are limited
• Initial purchase cost is important
• Demand comes from a small number of tools
• Higher noise is acceptable

Piston compressors should not automatically be selected for continuous production simply because the quoted CFM appears sufficient.

Rotary Screw Air Compressors

Rotary screw compressors provide a smooth supply of compressed air and are widely used in industrial and manufacturing environments.

They are commonly suited to:

• Regular or continuous demand
• Long daily operating periods
• Production environments
• Applications requiring quieter operation
• Sites where reliability and energy performance are important

Rotary Vane Air Compressors

Rotary vane compressors can provide dependable, smooth compressed air for regular and continuous applications. Their maintenance and lubricant requirements differ from conventional screw compressors, so model-specific support is important.

Variable-Speed Compressors

A variable-speed drive compressor adjusts motor speed to match changing air demand. This can reduce unload running and wasted energy where demand rises and falls during the day.

VSD technology is particularly useful where:

• Air demand changes significantly
• Production shifts or processes vary
• The existing compressor spends long periods unloaded
• Pressure stability is important
• Energy cost reduction is a priority

A VSD compressor is not automatically the best solution for every site. Where demand is consistently high and steady, a correctly sized fixed-speed machine may also operate efficiently.

Petrol and Diesel Air Compressors

Engine-driven compressors provide compressed air where a suitable electrical supply is unavailable. They are commonly used for mobile maintenance, construction, agricultural and remote-site applications.

They must be operated in suitably ventilated areas and should never be used where exhaust gases can accumulate.

Medical and Dental Air Compressors

Dental and medical applications can require clean, dry and low-noise compressed air from equipment designed for the relevant use.

Compressor selection should account for:

• Required air quality
• Oil-free or lubricated design
• Dryer and filtration requirements
• Noise and installation location
• Redundancy and standby requirements
• Applicable site and equipment standards

Smoke Ventilation Air Compressors

Smoke ventilation compressor systems are specialist life-safety installations. They may require duty and standby compressors, receivers, controls, monitoring and alarm integration.

These systems should be selected around the complete smoke ventilation design, not simply the compressor output.

Receiver-Mounted and Base-Mounted Compressors

Receiver-mounted compressors combine the compressor and air receiver into one package. This can simplify installation and reduce floor-space requirements.

Base-mounted compressors are installed with a separate receiver where required and can offer greater flexibility for larger systems and existing plant rooms.

Complete Compressor Packages

A compressor installation may also require:

• Air receivers
• Refrigerated or desiccant dryers
• Pre-filters and after-filters
• Condensate drains
• Oil-water separators
• Flexible connections and isolation valves
• Electrical isolators and protective devices
• Correctly sized pipework

The compressor should be considered as part of the complete compressed air system rather than as an isolated piece of equipment.

Electrical Supply

Check the available electrical supply before selecting a compressor. Larger machines may require three-phase power, suitable cable sizing, local isolation and correctly rated protection.

Starting current and control method should also be considered. Electrical work should be completed by a suitably competent person.

Ventilation and Installation Space

Compressors generate heat and require adequate cooling airflow. A machine installed in a poorly ventilated room may overheat even when correctly sized.

Allow space for:

• Cooling airflow
• Routine servicing
• Filter and separator replacement
• Access to electrical panels
• Safe lifting and component removal
• Future equipment replacement

Noise

Noise levels vary significantly between compressor technologies and enclosures. Piston and engine-driven compressors are generally louder than enclosed rotary screw or vane machines.

Where the compressor is close to offices, treatment rooms or occupied work areas, noise should be considered during selection and installation.

Allowing for Future Demand

A reasonable allowance for future growth can prevent the new compressor becoming undersized shortly after installation. However, excessive oversizing can increase capital cost and reduce efficiency.

Variable-speed control, receiver capacity and multiple-compressor arrangements can sometimes provide a better solution than selecting one significantly oversized machine.

Existing System Assessment

Where an existing compressor is being replaced, review:

• Actual running hours
• Loaded and unloaded operation
• Operating pressure
• Current airflow demand
• Pressure drop
• Leakage
• Existing dryer and filtration capacity
• Future production plans

Replacing an old compressor with one of the same motor power does not guarantee the new machine will match the site's actual needs.

A Real Example of Compressor Energy Savings

This is why we recommend reviewing real usage rather than simply replacing an older compressor with another machine of the same motor size.

Compressed Air Services