scroll air compressor

A scroll air compressor is a device used for air compressing and as a refrigerant. It is used in air conditioning devices, as a vacuumpump, and as an automobile supercharger. Many air conditioning systems and residential central heat pump and few automotive air conditioning systems employ a scroll air compressor instead of the traditional rotary air compressors and wobble plate compressors. A scroll air compressor operating in reverse is a scroll expander and can generate mechanical work.

How a scroll air compressor works

Scroll air compressors are positive-displacement devices that work by internal air compression. Air (or any other gas) is drawn in, trapped, reduced in volume, and lastly, discharged at the outlet port.

The two main components of a scroll air compressor are a stationary scroll and an identical moving scroll. Each is carefully machined in the shape of an involute spiral. In a typical design, the second scroll is rotated 180 degrees concerning the first, which lets the scrolls mesh. The moving scroll mounts on the eccentric crank offset from the center of the stationary scroll. However, the scroll does not rotate.

These movements create suction that draws gas from the outer inlet openings.  Gas the gets trapped in the crescent-shaped pockets between the two scrolls and continuous orbiting moves it steadily toward the center, therefore, reducing the volume and causing compression. Lastly, it reaches the center of the assembly where pressurized gas exit through the port.

The design of the discharge port determines the amount of external compression, similar to that in a screw air compressor. However, there are limits on the maximum amount of compression due to the size, shape, thickness, and strength of scrolls. The size of the outlet port also adds up to this. Scroll compressors can generate relatively high pressures of 100 to 150 psi in a single stage unit.

Scroll air compressors can offer several benefits for engineers, such as the units have few moving parts that can mean higher reliability, and they tend to have low maintenance requirements. Typical designs always run quieter than equivalent piston air compressors. Gas flow through the compressor is continuing, so this reduces the tendency for gas pulsation that can generate noise. Moreover, there are no inlet or discharge valves that create noise. They produce a smooth and vibration-free operation.

Why should you get a scroll air compressor?

The question you should ask yourself is, why is the scroll air compressor becoming a new norm in industrial and commercial applications? There are more advantages to using a scroll air compressor.

• Price

Before purchasing any scroll air compressors, you should check their prices and go for the one that favors your pocket. Scroll air compressor price should be one of the most factors to consider before buying one

• Reliability and life

Scroll air compressors have tons of advantages over other compressors; for example, they have much fewer moving parts. The less moving parts you have, the less maintenance you have to do. This also shows that fewer things could go wrong. This situation results in a more reliable and longer-lasting compressor.

• Torque variation

Since the compressor has simple motion, it has less torque variation, which results in much smoother operation and less noise.

• Humidity control

Variable-capacity and two-stage compressors are known for their ability to control humidity. They can hold temperatures in a home well and match the exact need of the house. This results in better control humidity.

Whether you are a heavy-duty mechanic, automotive technician, or a contractor, you need an air compressor that keeps you up. Here is a scroll air compressor buying guide to help you choose the right compressor:

• Horsepower

The horsepower rating should be the best guide for determining the size of the compressor you need. Unfortunately, the marker guys have been exaggerating horsepower ratings to help sell more compressors. Industrial compressors are usually accurately rated.

• Air pressure

Air pressure is always rated in pounds per square inch or PSI. Most of the air tools require about 90PSI to run correctly. However, to maintain 90PSI at the machine, you need a compressor with a higher shut-off pressure. Many industrial compressors are two-stage, which means they build up to shut off pressure in two different stages.

• Cubic feet per minute CFM

Air tools require a particular volume to keep them working smoothly. The amount that an air compressor produces is rated in cubic per minute CFM.

• Air compressor tank size

An air compressor does not produce air. It only stores air. It is essential to have a big enough pump and motor because if you are providing as much air as you want to, you will never run out of air no matter how small the tank is. However, if you only use air intermittently, then you can save money by getting a smaller compressor with a large tank. This means that the compressor can build pressure until you need to repeat the job.

On the other hand, if you want to run a tool steady, such as the sender, then it is essential to be producing as much air as you need. A smaller tank is more portable and gets up to pressure quicker while a compressor with a small tank does not stop as often and cools the air in a bit better. A large tank does not mean that the compressor runs less, it starts and ends less often, but the running time is just the same as if it had a smaller tank. Tank sizes are always measured in US gallons

Single-stage and two-stage air compressors

Single-stage compressors have one more cylinder, and each cylinder pumps air directly into the tank. Two-stage compressors have at least two cylinders, and the air is pumped from one cylinder into another and then into the tank.

The main reason forbuying atwo-stage compressor is if you need high pressure, but not many applications need high pressure; therefore, you probably don’t need a two-stage compressor. For many applications, you would better go with a good quality single-stage compressor instead of low-cost compressors.

Direct drive or belt drive, oil or oil-less air compressors

There is also a wide variety of portable scroll air compressors available to you, such as Turkey. You can also choose from oil-free scroll air compressors, lubricated and oil-less portable scroll air compressors. There are as many as 360 suppliers who sell portable air compressors.

There are very many better compressors in both belt drive and direct drive versions. The problem is that most of the direct-drive compressors were designed to keep the cost down for big-box stores, and that means low quality. Direct drive compressors are directly connected to the motor. Most decent direct drive compressorsare small in RPM. Some engineers have designed compressor to spin twice as fast to get more air out of them and keep the price know for the big box stores. However, the life expectancy is cut down to about one-quarter of that low RPM compressor, and it produces a lot of noise.

Some direct drive compressor is oil-less, which is very important for some application such as breathing air or aeration. If the compressors are low in RPM and built right, then they should be able to last longer.

Most belt drive compressors aresplash lubricated, which means they have dippers on the bottom of the connecting rods to splash oil around in the compressor crankcase. For best value, get a belt-drive, oil-lubricated compressors and stay away from full high speed, oil-less compressors unless you want to carry it around.

In most cases, suction or discharge valves are not used in scroll compressors. But electric discharge valves are preferred at the compressor discharge when operating at high differential pressure values. In such cases, having an active valve at the discharge increases the efficiency of managing the compressor. For instance, scroll compressors operate at high differential pressure, for example, refrigerationapplications. In such cases, dynamic discharge valves are preferred.

But in other cases, like air conditioning, having a discharge valve results in pressure losses, reducing the efficiency; hence these are not alwayspreferred.

Advantages of scroll air compressors

Scroll type compressors are more efficient compared to other types of compressor form many reasons like:

1. The absence of piston for gas compression enables scroll compressors to reach the full percentage of volumetric energy leading to reduced energy loss
2. Re- expansion losses, a typical feature of each piston stroke encountered in reciprocating models, are eliminated. Moreover, valve (ports) losses are reduced, since suction and discharge valves do not exist.
3. They do not need spring suspension due to lover vibration and noise.
4. Scroll compressors are considerably quieter in operation compared to other compressors due to the absence of several moving parts.
5. Scroll air compressors are more durable because they have fewer moving parts, lower vibrations, and less friction.
6. Gas pulsation is also minimized if not eliminated, and therefore they can operate with less vibration.

Disadvantages of scroll air compressors

1. The most significantdisadvantage of scroll compressors is that they are usually not repairable. They cannot be dissembled for maintenance because they are fully hermetic.
2. Many reciprocating compressors are free in rotating in both directions. This is not always the case for scroll air compressors.

Application their production, scroll air compressors have been successfully used in applications involving the following:

• Food and fruit refrigeration
• Truck transportation
• Vacuum pumps
• Marine containers
• residential and small to medium scale commercial air-conditioning applications

Scroll air compressor brands

• Atlas Copco– they opened their door in 1907 and delivered the first-ever mobile air compressor. This brand offers an industrial air compressor that is made with quality in mind.
• Quincy– it was founded in 1920, and they continue to lead the pack when it comes to air technology. This brand also sells scroll compressors in the industrial application side.
• Powerex– this is the last brand in the industrial category. Founded in 1988, their only focus has always been the engineering sides of things.
• Copeland- it is a light-duty compressor. They are the best name in air technology. They roll out newer generations of technology, and that applies to their scroll compressor operations too.
• Eastwood – this is also another brand that is known for smaller scroll compressors. Their products are mostly aimed towards garages, shops, and hobbyists’ market. They produce small scroll air compressorsthat are very powerful and more efficient while minimizing noise.
• Danfoss- they are majorly known for building light-duty scroll compressors. They sell units for refrigeration.