Scroll compressors are ideal for industries requiring lower output, quieter operations, a smaller footprint, and improved energy efficiency. They use a scroll mechanism with a spiral-like design to compress crescent-shaped air pockets to the required pressure level.
This gentler, oil-free approach relies on displacement compression technology. It is widely used in food manufacturing, HVAC installs, dentistry, medical clinics, and other industries.
1. What is a Scroll Compressor?
A scroll compressor uses two spiral elements to compress air. One spiral stays fixed while the other orbits around it, creating pockets of air that shrink as they move toward the centre. This gives steady pressure without the pulsing you get from piston models.
These units have fewer moving parts than other compressors. The two scrolls never actually touch, which cuts down on noise and wear. At the Bristol Royal Hospital, maintenance staff replaced their old compressors with scroll units in 2021, reducing noise in the children’s ward from 71 to 59 dB – about the normal conversation volume.
You will find scroll compressors in places that need clean air and quiet operation. The Oakfield Dairy near Chester uses four small units in their yoghurt production area, running 18 hours daily. They are housed in a standard grey metal cabinet about the size of a washing machine, with a simple control panel on the front.
Scroll compressors cost more upfront than rotary models – a typical 5 kW unit runs about £1,200 compared to £750 for a similar piston model. However, many users find lower electricity bills make up the difference within two years. According to their facilities manager’s records, the units at Westland College had paid for themselves after 22 months of use.
2. How do Scroll Compressors Work?
Scroll compressors use two spiral elements to compress air. One scroll stays fixed while the other orbits around it. This movement traps air between the scrolls. As the orbiting scroll moves, the space between scrolls gets smaller, squeezing the air toward the middle.
The compressed air exits through a centre port with a check valve that stops air from flowing backward. Scroll units run quietly with just one moving part and no metal touching metal. The workshop at Bedford College measured their new scroll unit at 61 dB, about the same volume as normal conversation.
Scroll compressors make less noise than reciprocating types. They also need fewer repairs and produce less vibration. St Mary’s Surgery in Luton installed one last autumn in their basement, just below the consultation rooms. Staff noticed the difference immediately compared to their old piston unit.
Most scroll units come fully sealed. They serve various needs, from the dental practice in Norwich, which runs three small units to cool their treatment rooms, to the microbrewery in Bath, where two larger units power their bottling line. These compressors work best for applications needing up to 30 kW of power. The scrolls look like two snail shells fitted together, one able to move while the other stays put.
3. Types of Scroll Compressors
There are different types of scroll compressors to choose from:
Oil-Free Scroll Compressors – Best for businesses needing clean, oil-free, compressed air. This includes food & beverage, medical, and other fields.
Oil-Lubricated Scroll Compressors – Although less common, oil-lubricated scroll compressors are also available. These require oil for sealing and lubrication purposes and meet some industrial requirements.
Single-Stage Compressors – These compress either air or gas using a simpler Atlas Copco’s one-stage process to get results. Most often seen in smaller air platforms.
Two-Stage Compressors – These compressors support air pressurisation at higher levels than are usually possible with single-stage machines. The second stage boosts the pressurisation created by the first stage.
Modular Scroll Compressors – Incorporating multiple smaller scroll units that often work in unison. These offer similar energy efficiency while providing greater flexibility to scale up air production.
Are you unsure which scroll compressor is right for your business? Contact our team to discuss your needs.
4. Applications of Scroll Compressors
Compressors are becoming more popular across a range of industries. Below, we discuss common applications of scroll compressors:
Medical equipment: healthcare facilities, including dental clinics, require oil-free compressed air to complete operations.
Automotive: vehicle superchargers are becoming a preferred option for improved cooling.
HVAC systems: the air conditioning systems needed to support HVAC often use scroll compressors. They offer greater efficiency, low maintenance, and reduced decibels during operation.
Food transportation: reliable refrigeration and air conditioning are essential for food transportation. Otherwise, food may spoil earlier than expected.
Accurate industrial processes: scroll compressors’ consistent air quality and reliable air flow are prized features.
5. Advantages of Scroll Compressors
There are pronounced advantages to using scroll compressors. Below are a few of them:
Quieter Operation
Because scroll compressors have only a single moving part, they are quieter. For example, the Atlas Copco SF series emits as low as approximately 53dB while offering a capacity of 7.6 litres per second at 145 psi (10 bar).
Energy Efficient
Zero metal contact and fewer moving parts mean considerably less energy is spent creating compressed air, reducing electricity costs.
Compact
This compressor type fits into small spaces, making it easier to install. As such, it supports compact environments, such as refrigerated delivery vans and HVAC systems.
Clean, Consistent Air Quality
Oil-free scroll compressors produce higher air quality that passes the ISO 8573-1 Class 0 standard. This is beneficial for the pharmaceutical, beverage, food, and other industries requiring oil-free production lines.
Reliability
These compressor types are ideal for creating dry air without significant contaminants. Zero oil and the simple design of the scroll keep these compressors operating fault-free for longer than other alternatives, reducing the inconvenience and loss from frequent shutdowns.
6. Disadvantages of Scroll Compressors
Scroll compressors perform well. However, they do have some disadvantages to be aware of:
Capacity Restrictions – Air system requirements at a small to medium flow rate are ideal. While modular scroll compressors offer good capacity, they are no substitute for a powerful screw compressor or a reciprocating compressor.
Higher Cost – Scroll compressors are more expensive than reciprocating compressors. However, operating expenses are lower throughout their lifespan because of reduced energy expenditures and less wear, creating fewer maintenance issues.
Maintenance – Scroll machines create fewer maintenance problems than piston compressors. However, because of their complexity, they require disassembling to fix certain issues.
Discuss your exact needs with our compressor experts. They will steer you in the right direction.
7. Scroll Compressors vs Other Compressor Types
Let us compare scroll compressors to other compressor types:
Screw compressors: while more energy efficient, scroll compressors do not support the high capacity required by many substantial operations. Screw compressors deliver higher capacity where it is needed.
Rotary compressors: scroll compressors have a higher initial purchase expense. However, they provide smooth, consistent performance over rotary compressors.
Reciprocating compressors: their energy efficiency and quietness have reciprocating compressors’ beat. Yet, scroll compressors do admittedly cost more to purchase.
8. Considerations for Choosing a Scroll Compressor
What should you ponder when looking at a scroll compressor?
First, consider whether an oil-free or oil-lubricated compressor is required. Most scroll compressors are oil-free machines.
Second, what are the necessary capacity and air pressure levels? Will a scroll compressor support these requirements?
Beyond this, look at the total cost of ownership. Sure, the initial cost of the air system is higher; however, these compressors are low maintenance, run efficiently, and use less energy per litre of compressed air delivered.
Also, ensure the compressor is compatible with any existing air systems.
Conclusion
Scroll compressors meet a specific need. They offer compactness, energy efficiency, and improved reliability. They are an excellent option for low-to-medium air flow and pressure requirements, dependable performance, and limited maintenance.
While effective, they may not suit every industrial or commercial situation. For the best results, consult our experts at J Ll Leach.
FAQ
What makes a scroll compressor different from other types of air compressors?
Scroll compressors use two spiral elements – one fixed, one orbiting – to compress air. They have fewer moving parts than reciprocating or rotary models. A basic scroll unit runs at 62 dB while a reciprocating model reaches 72 dB.
Leicester Royal Infirmary installed four scroll units in their east wing in 2022, mainly to cut noise near the paediatric ward. You will find these compressors in hospitals, small food packaging plants, and air conditioning systems where clean air matters.
Is a scroll compressor suitable for my air conditioning system?
Scroll compressors suit most home air conditioning systems. They do not have the jarring start-stop pattern you get with piston types. A typical 5 kW home unit draws 6.8 amps and needs about 30 seconds to fully operate after startup. Without valves to maintain, service intervals stretch to 8,000 hours rather than the usual 4,000.
Edinburgh Technical College switched twelve units from piston to scroll in their main building last winter. The caretaker noted fewer temperature complaints from staff in rooms 112–148, which had previously suffered from cold spots.
What are the advantages and disadvantages of using a scroll compressor?
Scroll compressors run quietly and need less upkeep. They produce a steady air flow and take up little space – a 3 HP unit sits in a 40 cm square footprint. The Cooper Street Medical Centre in Manchester houses theirs in a former broom cupboard.
However, they cost £800–£1,200 more upfront than comparable piston models and output tops around 30kW, which is insufficient for heavy workshop use. Blackwater Brewery in Manchester uses scrolls for their bottling machines but installed screw compressors for their main production floor. Cooling matters, too – a scroll unit needs room temperature below 40°C, and the service manual recommends installing them at least 45 cm from any wall to allow proper airflow.
