Air receivers are often overlooked components in compressed air systems. They have no moving parts (except for drains) and operate quietly and reliably- provided they are properly maintained. Yet their role is crucial: they provide buffer storage, absorb peaks in air demand, stabilize pressure, and reduce compressor load/unload cycles.

When correctly selected and installed, air receivers allow compressors to respond efficiently to fluctuations in demand and significantly contribute to the reliability and energy efficiency of the entire compressed air system.

Air receivers also collect condensate, improving dryer performance and protecting pneumatic tools and production processes. However, accumulated condensate can affect the structural integrity of the vessel over time, which makes safety a critical factor when selecting air receivers.

 

Key Design Parameters

The three fundamental parameters when designing a compressed air station are:

  • Flow rate
  • Pressure
  • Air quality

These parameters determine the size of all components: filters, dryers, piping - and also the size of the air receiver(s).
Each component must have a maximum allowable working pressure (MAWP) greater than the compressor's operating pressure.

Example:
If a compressor operates at 8.5 bar(g), all downstream equipment - dryers, filters, piping, and air receivers - must be certified for at least the same pressure.

 

Safety Above All Else

Air receivers are manufactured according to specific pressure requirements and must strictly comply with the European Pressure Equipment Directive PED 2014/68/EU.
Common standardized MAWP ratings include:

  • 11 bar(g)
  • 16 bar(g)
  • 40 bar(g)

Each air receiver must be equipped with the following essential safety devices:

1. Pressure Gauge

  • Must measure at least up to the tank's maximum allowable pressure.
  • Should be sufficiently large and easy to read at a glance.
  • Must be installed in a visible and easily accessible location.
  • Best practice: install an isolation valve between the gauge and the tank to simplify replacement.

2. Pressure Relief Valve (Safety Valve)

  • Must be sized for the system's full airflow.
  • Must be set to open at or slightly below the maximum allowable working pressure.
  • Must be installed where it can be inspected easily.
  • Since it may open at any time, it must be positioned so that personnel are protected from the exhaust airflow.
Important: No isolation valve is permitted between the air receiver and the relief valve.

3. Drain Valve

  • Must be connected at the lowest point of the tank.
  • Manual drains are the least effective option - they are either left closed (no drainage) or left open (significant air losses).
  • The recommended solution is a zero-loss drain, such as the KAESER ECO-DRAIN, which opens only when condensate is present and includes a test button for easy verification.

MAVA Industrial provides a wide range of cost-effective, zero-loss drainage solutions suitable for any installation.

 

Where and Why to Install Air Storage

Proper placement of air receivers is essential for system stability.
Best practice, wherever possible, is to install two air receivers.

1. The "Wet" Air Receiver

  • Installed immediately after the compressor, before the dryer.
  • Acts as a buffer and smooths pressure fluctuations.
  • Aids in initial condensate separation.
  • Mandatory: a reliable automatic drain, preferably zero-loss.

2. The "Dry" Air Receiver

  • Installed after the dryer and final filters, before entering the distribution network.
  • Stores dry, clean air.
  • Reduces pressure drops across the network.
  • Ensures stable peak supply and responsiveness to short-term consumption spikes.

Local Point-of-Use Storage

For applications with sudden and intense peaks, installing a small air receiver near the consumer often proves highly effective. This ensures peak demands are met locally without causing pressure drops across the entire network.

 

Sizing - Volume Matters

Sizing air receivers is generally straightforward - and slight oversizing rarely causes issues.
Undersizing, however, leads to:

  • frequent load/unload cycles,
  • unstable system pressure,
  • increased wear,
  • higher energy consumption.

General rule of thumb:

For a base-load rotary screw compressor:

Air receiver volume ≈ 30% of the compressor's maximum free air delivery (FAD).

This ensures the system can maintain airflow for at least 30 seconds, providing enough time for the compressor to start and load without causing significant pressure drops.

 

Weight and Mechanical Support

A common question is whether an air receiver can be installed on a mezzanine.
The answer is yes, but only if the structure can safely support the maximum possible weight, including when the tank is completely filled with water.

Air receivers contain enormous stored energy. If not properly anchored or supported, they can pose severe safety risks, including tipping, falling, or catastrophic failure.

  • All receivers are equipped with support legs, which must always be securely anchored.
 

Periodic Inspection

Air receivers must undergo regular assessments to ensure safe operation. Many are equipped with a manway opening for internal inspection. According to European legislation, air receivers must be:

  • inspected every 5 years by a certified external body, and
  • installed with adequate clearance to allow for proper maintenance and internal examination.
 

Conclusion

Although they operate quietly in the background, air receivers play a decisive role in the performance and safety of a compressed air system:

  • They stabilize pressure.
  • Reduce compressor cycling and wear.
  • Store air for short-term peak demand.
  • Support water separation and protect production equipment.

When properly sized, installed, and protected, they require minimal attention and deliver long-term reliability.

 

Need Expert Support?

The specialists at MAVA Industrial - official partners of KAESER - have extensive experience in:

  • designing compressed air stations,
  • analyzing consumption patterns,
  • sizing receivers, dryers, filters, and piping,
  • optimizing energy efficiency in industrial environments.

For technical consultation based on your installation's real requirements, our team is ready to assist.