What Size Air Receiver Do I Need for a CNC Workshop?
A practical guide to compressed air receiver sizing for CNC machinery, laser cutting, press brakes and manufacturing workshops, including peak demand, pressure stability, compressor cycling and future expansion.
Key areas covered in this guide
Receiver capacity should be selected around the compressor, machinery demand and control method rather than chosen by floor space or connection size alone.
What Size Air Receiver Do I Need? The Short Answer
There is no single air receiver size suitable for every CNC workshop. The correct capacity depends on compressor output, operating pressure, demand fluctuations, compressor control method, pipework volume and the number of machines connected to the system.
Many smaller workshops use receivers in the 270-litre to 500-litre range, while larger manufacturing sites may need 1,000 litres or more. These figures are only broad examples and should not replace a proper system assessment.
A large receiver cannot permanently compensate for an undersized compressor. Stored air can support short peaks, but the compressor must still meet the site's continuous demand.
What Does a Compressed Air Receiver Do?
An air receiver stores compressed air and acts as a buffer between the compressor and the machines using the air. It helps the system respond to short changes in demand without relying on the compressor to react instantly to every pneumatic movement.
Why CNC Workshops Benefit From Compressed Air Storage
CNC and manufacturing workshops often have highly variable compressed air demand. Machinery may cycle, pause, start again or use short bursts of air for pneumatic movements.
- Laser cutting machines may use compressed air for pneumatic functions or approved assist-air processes
- Press brakes may use air for clamping, guarding, supports or automation
- Tool changers and handling systems create short demand peaks
- Air tools may operate intermittently across the workshop
- Several machines may call for air at the same time
- Production demand may change between shifts or jobs
The receiver acts as a buffer between these changing demands and the compressor. Correct storage can improve stability, but it must be paired with a compressor capable of replenishing the air used.
What Determines the Correct Air Receiver Size?
| Sizing Factor | What to Check | Why It Matters |
|---|---|---|
| Compressor output | Delivered airflow at the operating pressure. | Higher output generally requires suitable storage and control volume. |
| Demand pattern | Steady demand or short, high-flow peaks. | Highly variable loads may benefit from additional storage. |
| Operating pressure | Normal system pressure and usable pressure range. | Pressure difference influences how much usable air is stored. |
| Compressor control | Fixed speed, start-stop, load-unload or VSD. | Control method affects cycling and storage requirements. |
| Machine count | Number of simultaneous compressed air users. | Several machines can create overlapping demand peaks. |
| Pipework volume | Total distribution network size. | The pipework itself provides some additional storage volume. |
| Future expansion | Additional machinery or longer production hours. | Avoids choosing storage that becomes inadequate too quickly. |
Typical Air Receiver Sizes for CNC and Manufacturing Workshops
The examples below are broad starting points only. Receiver selection should be checked against the compressor, demand pattern and system design.
| Example Compressor Size | Common Receiver Range | Possible Application | Important Note |
|---|---|---|---|
| 5.5kW | Approximately 270 litres | Small workshop or light CNC demand | Check peak usage and compressor control method. |
| 7.5kW | Approximately 270–500 litres | Small manufacturing workshop | 500 litres may suit more variable or expanding demand. |
| 11kW | Approximately 500 litres | CNC, fabrication or engineering workshop | Confirm whether multiple machines can operate together. |
| 15kW | Approximately 500 litres | Medium industrial compressed air system | Additional storage may be appropriate for short high-flow peaks. |
| 22kW | Approximately 500–1,000 litres | Production workshop or manufacturing facility | The KUT Machinery system includes a 500-litre vertical receiver. |
| 30kW and above | 1,000 litres or more | Larger industrial or multi-machine systems | Central and local receivers may both be considered. |
These are examples, not fixed rules. A smaller compressor serving a highly intermittent application may need more storage than a larger compressor operating against steady demand.
How an Air Receiver Supports Peak Demand
Some CNC equipment uses short bursts of compressed air rather than a constant flow. During those brief periods, the machine demand may be higher than the average workshop demand.
A suitably sized receiver can release stored air during the peak and then be replenished by the compressor afterwards.
Peak storage is not continuous capacity. If the high demand continues for a long period, the compressor must be able to supply the required airflow without relying on the receiver.
How Receiver Size Affects Compressor Cycling
A receiver that is too small may cause pressure to rise and fall rapidly, resulting in frequent compressor start-stop cycles or repeated load-unload events.
Excessive cycling can increase wear, reduce control stability and create avoidable electrical and mechanical stress.
Fixed-Speed Compressors
Fixed-speed compressors may use receiver capacity to increase the time between loaded and unloaded operation or between starts and stops.
Variable Speed Compressors
VSD compressors adjust output to follow demand, but they still benefit from suitable system volume. If demand falls below the compressor's minimum stable output, adequate storage can help reduce rapid cycling.
Should the Air Receiver Be Installed Before or After the Dryer?
Receiver position depends on the system design. A wet receiver is installed before the dryer, while a dry receiver is installed after the dryer.
| Receiver Position | Potential Advantages | Important Considerations |
|---|---|---|
| Before the dryer | Can cool compressed air, collect condensate and reduce short flow peaks entering the dryer. | Requires effective drainage and suitable corrosion management. |
| After the dryer | Stores treated air and can support downstream peak demand. | Dryer and upstream equipment must handle the compressor's changing flow. |
| Receivers in both positions | Can provide upstream conditioning and downstream treated-air storage. | More common in larger or carefully engineered systems. |
There is no universal layout. Receiver position should be considered alongside dryer sizing, condensate drainage, pressure drop and the demand profile.
Vertical vs Horizontal Air Receivers
Both vertical and horizontal receivers can provide effective compressed air storage. The best arrangement usually depends on plant-room layout, access and equipment configuration.
Vertical Receivers
- Use less floor space
- Often suit compact plant rooms
- Can be positioned alongside upright equipment
- Provide straightforward low-point drainage
Horizontal Receivers
- May suit low-height installations
- Can be supplied as compressor-mounted arrangements
- May provide a stable base for packaged equipment
- Require sufficient floor space and service access
Can a CNC Workshop Use More Than One Air Receiver?
Yes. Larger or more complex systems may use a central receiver near the compressor and one or more local receivers close to high-demand equipment.
Local receivers should not be added without considering pressure, drainage, isolation, statutory inspection and the ability of the compressor to refill the stored volume.
Air Receiver Safety, Inspection and Maintenance
An air receiver stores compressed air under pressure and must be installed, maintained and inspected appropriately.
- Receiver pressure rating must suit the compressor system
- A correctly rated safety valve must be fitted
- Pressure indication and isolation should be provided where required
- Condensate must be drained safely and regularly
- The vessel should be protected from corrosion and physical damage
- Maintenance access must be retained
- Applicable examination requirements must be considered
Depending on the system, the Pressure Systems Safety Regulations may require a Written Scheme of Examination and periodic inspection by a competent person.
Do not modify, weld or repair a pressure vessel without suitable specialist assessment. Damaged or heavily corroded receivers should be taken out of service and assessed by a competent person.
Real Installation Example: 500-Litre Receiver at KUT Machinery
Compressed Air Systems UK supplied a complete Tanair compressed air system for the KUT Machinery showroom in Kidderminster.
The installation includes a 500-litre vertical air receiver alongside the 22kW variable speed compressor, refrigeration dryer, filtration and compressed air distribution pipework.
The receiver was considered as part of the complete system rather than selected in isolation. Compressor output, showroom demand, pressure stability, available floor space and system layout were all relevant.
- Tanair TAN-S 22VSD compressor
- Up to approximately 113 CFM
- 500-litre vertical air receiver
- TAN-RD-36 refrigeration dryer
- High-efficiency filtration
- Condensate-management equipment
- Compressed air pipework
- Testing and commissioning