How to Choose the Right Air Receiver Tank Size
The air receiver tank is one of the most overlooked components in a compressed-air system, yet it plays a crucial role in efficiency, pressure stability and compressor life. Choosing the right tank size helps reduce energy use, prevent cycling and ensure consistent air supply to your tools and production line. This guide explains how to calculate the correct receiver volume for your ABAC, Atlas Copco, FINI, NUAIR or HPS compressor system.
1. What an Air Receiver Does
An air receiver tank stores compressed air and smooths out pressure fluctuations. It allows your compressor to run at full load for longer periods rather than starting and stopping every few seconds. This reduces wear, saves electricity and gives your tools a more stable air supply.
- ⚙️ Acts as a buffer between compressor and system
- 💧 Allows condensate to drop out and be drained
- 🔧 Provides surge capacity for high-demand tools
- 📉 Reduces on/off cycling and extends motor life
2. The Rule of Thumb for Tank Sizing
A simple guideline is to allow **6–10 litres of storage per CFM** of compressor output for workshop use, or **20–30 litres per CFM** for systems with large demand peaks.
Example: a 10 CFM piston compressor requires roughly 100 litres of receiver capacity, while a 50 CFM screw compressor should have 500–1,500 litres depending on usage pattern.
3. The Formula Method
To calculate precisely, use:
V = (Q × t × (P₁ / (P₂ - P₁)))
Where:
- V = tank volume (litres)
- Q = air consumption (litres/min)
- t = acceptable compressor off-time (minutes)
- P₁ = minimum pressure (bar abs)
- P₂ = maximum pressure (bar abs)
Example: If you want the compressor to rest for 1 minute between 8 and 10 bar while supplying 1,000 l/min:
V = 1,000 × 1 × (9 / (10 - 9)) = 9,000 litres
That’s a large tank — in practice, most users compromise between space, budget and performance.
4. Piston vs Screw Systems
Piston compressors produce pulsating air, so a larger tank (100–300 litres) smooths delivery. Screw compressors deliver continuous flow, allowing smaller receivers (250–500 litres) if fitted with a load/unload control. Multi-compressor installations often use a single central tank sized for combined flow.
5. Receiver Orientation
- Horizontal: Easier to mount under smaller units; ideal for mobile and workshop setups.
- Vertical: Saves floor space, improves condensate drainage and is preferred for industrial screw systems.
6. Pressure Ratings
Always match or exceed your compressor’s maximum working pressure. Most UK receivers are rated at 11 or 15 bar with CE certification. Never use unverified or unmarked vessels—pressure systems fall under UK PSSR (Pressure Systems Safety Regulations).
7. Drainage and Moisture Control
Receivers naturally collect condensate as compressed air cools. Fit a manual drain or, better, an automatic drain valve. Regular draining prevents corrosion and protects downstream dryers and filters.
8. Installing the Receiver
- Install between the compressor and main air distribution line.
- Use flexible hoses to isolate vibration.
- Fit a pressure gauge, safety valve and isolation valve.
- Mount securely on level ground with anti-vibration pads.
9. Sizing for Multiple Compressors
If you run more than one compressor, total the combined FAD (Free Air Delivery) and apply the same 6–10 litre per CFM rule. It’s often better to install a single large 1,000–3,000 litre receiver than several small ones—it balances load between units and stabilises the system.
10. Energy Efficiency and Load Control
A properly sized receiver lets your compressor operate in longer, more efficient load cycles. For screw compressors, aim for at least 1–2 minutes of off-time per cycle. Each unnecessary start adds wear to contactors and motors. Energy savings of 5–10 % are typical simply from optimal tank sizing.
11. Compliance and Certification
Under UK law, receivers over 250 bar-litres require a written scheme of examination by a competent person. All vessels must display:
- Manufacturer name
- Design pressure and test date
- Serial number
- CE or UKCA mark
Inspect tanks annually for corrosion, damaged fittings and safety valve function. Replace corroded receivers immediately.
12. Example Sizing Table
| Compressor Flow (CFM) | Suggested Receiver (Litres) | Example Model |
|---|---|---|
| 5 – 10 | 100 – 200 | ABAC Pro A39B |
| 15 – 25 | 250 – 500 | FINI MK 113 |
| 30 – 50 | 500 – 1,000 | Atlas Copco GX 7 / ABAC Genesis 7.5 |
| 60 – 100 | 1,000 – 2,000 | HPS 15 / 22 kW Screw |
| 100 + | 2,000 – 5,000 | Industrial multi-compressor systems |
13. Receivers for Oil-Free Systems
Oil-free scroll and dental compressors need stainless-steel or internally coated receivers to prevent rust and contamination. These tanks should include sterile filters and bacterial traps for medical compliance (HTM 01-05 or ISO 8573 Class 0 air).
14. Space and Acoustic Considerations
Large vertical receivers can reduce noise by acting as silencers. Always allow at least 500 mm clearance around tanks for inspection and access. If installing indoors, ensure adequate ventilation and floor loading capacity.
15. Example: Sizing for an ABAC Genesis 7.5
At 7.5 kW and 40 CFM output, a 500–750 litre receiver provides ideal balance between cost and performance. The compressor will run for 3–4 minutes per cycle and rest for around 1–2 minutes, ensuring low wear and stable pressure.
16. When to Replace a Receiver Tank
- Visible corrosion or pitting inside the vessel
- Frequent water discharge even after draining
- Safety valve lifting below rated pressure
- Out-of-date inspection certificate
Always replace ageing receivers with certified CE/UKCA tanks. It’s illegal to weld or repair pressure vessels without re-testing.
17. Accessories to Consider
18. Key Takeaways
- Size receivers at 6–10 L per CFM for general use.
- Choose vertical tanks to save space and improve drainage.
- Drain daily and inspect annually for corrosion.
- Fit automatic drains and safety valves for reliability.
- Correct sizing improves energy efficiency by up to 10 %.
FAQs
Can a receiver be too large?
Rarely. Larger tanks reduce cycling but increase cost and footprint. For workshop use, balance space against compressor duty cycle.
Do I need a receiver if my compressor already has one built-in?
Yes—built-in tanks are often too small. Adding an external receiver improves pressure stability and protects the compressor motor.
How often should I drain my receiver?
Daily for manual drains or weekly if using an automatic valve. Moisture accumulates faster in humid conditions.
Are vertical receivers safer?
Both orientations are safe if certified and installed correctly. Vertical tanks are simply more space-efficient and easier to drain.
See also: Compressor Installation Best Practices