Ins and Outs of Cold Room Compressors  

Do you know what a cold room compressor is? No? You’re not alone. Many people are completely unaware of what a cold room compressor is or what it does.
We’re going to change that! In this post, we will break down what a compressor is and the different kinds of compressors.

Compressor, What Exactly are They?
Compressors are the workhorse of cooling units. They take the hot vapour refrigerant away from the cold room’s evaporator system. Essentially they condense vapour to reduced volumes at higher temperatures. Some use electric motors, while others work with a belt and pulley system.

Encompassing reed valves that help regulate circulations of refrigerant during the pumping phase, compressors work to keep the cold rooms cold. However, suppose the valves aren’t tightly held. In that case, there’s a possibility of gas leaking into the lower side during a compression stroke.

Relief valves exist to control and monitor the pressure and automatically stay open to relieve stress if discharge pressures exceed their usual amounts. There are a few different types of commonly used compressors which include;

  • Reciprocating
  • Rotary
  • Screw
  • Centrifugal
  • Scroll


6 Types of Compressors

There are five different types of commonly used compressors that all achieve the same goal through various methods. While the same in function, their ways of compressing the refrigerant vapor vary from compressor type to type.


Reciprocating compressors are also referred to as piston compressors. They get this name from using a piston that moves within the cylinder and compresses refrigerant with the help of a crankshaft.

 The piston’s pushed down as vapor coming from suction lines is delivered to an intake valve. As it moves up, the refrigerant compresses. It then travels into the compressor’s exhaust valve and eventually finds its way to a condenser. With a motor engine-like construction, the rotary motion is achieved.

2 valve sets perform an absorption and expulsion of air. Single-way valves make sure that any absorbed air can’t seep through and also keeps compressed air from moving backward as the reciprocating compressor’s piston once again goes down.

There are multiple types of cylinders called multi-cylinder compressors which can have; two cylinders, four cylinders, eight cylinders, and so on.


The rotary compressors contain the compressor and motor in a tightly sealed environment creating an enhanced driver method. As a result, there is a constant interaction between refrigerant and motor. This leads to the gas compressing and creating pressure variance to assist in easy refrigerant mobility throughout the system in the rotary compressor.

Stationary Rotary

The motor drives a cam, causing a ring to move along with it and move to the external rim along the wall of the cylinder. Vapor’s produced by the evaporator, which goes to the compressor through the holes within the frame.

To achieve gas compression, the use of a rotating offset ring is required. This barrier splits the intake and exhaust ports. While the vapor is taken in by the compressor, the barrier becomes grasped against the rin with support from the spring. The ring, in turn, moves around the cylinder to perform gas compression before being pushed into the compressor’s condenser.

Rotating Blade

Two roller blades are aligned to a 180-degrees separated distance and move across the side of the cylinder. The roller is erect and moves to connect with the intake and discharge ports.

As the roller starts moving, the vapour flows to the intake port, makes its way into the cylinder, and traps it inside, sealed. The next blade moves beyond the contact point, thus nearly compressing the vapour. Once reaching a certain value of pressure, it continues to move through the exhaust and into the condenser.


Centrifugals, or radial compressors, are used in high-capacity refrigeration systems. Centrifugal compressors rotate vapor in circular motions, which is called centrifugal force (hence the name).

Impeller disks made up of radial blades begin to rotate in the housing and drive gas towards achieving higher speeds. Then, a diffuser takes the energy and transforms it into new pressure energy, provided to the centrifugal condenser as the pumping efficiency increases. Centrifugal compressors work at higher velocities by design.

Centrifugals are popular due to their simple design elements, fewer active parts, and energy efficiency in operating in a variety of stages.


Screw compressors are driven primarily by electric motors or diesel engines. These compressors use screws or helical rotors that interlace before compressing refrigerant while the roots revolve inside the cylinder.

Low-pressurized refrigerant moves to one side of the compressor. A high-pressurized refrigerant gets expelled to the other side.

Screw compressors contain fabricated male and female rooters. The male rooters are made of 4 lobes and are connected to 6 flutes, all of which corresponds to the female rooter. Large amounts of lubricant oils lower the temp of the compressed air. In addition, oil shuts the gap that’s left by a lack of intercoolers.


With scroll compressors, you get clean compressed air and all done noise-free. They are reliable, quiet, and a prevalent compressor type available because of these factors. This is the compressor frequently used in fridges, freezers, and similar products in order to pump and distribute freon.

The scroll design is unique in that it has only a single moving part. The compressor contains dual spiral components, and while one moves in unconventional circles, the other remains stationary. As this singular rotation happens, the refrigerant between them is relocated to the center. This all results in a reduction in the volume of gas. This reduced quantity of gas is discarded through the condenser’s center port.

 When scrolls work in reverse, it’s called scroll expander. This creates energy, mechanical in nature, and works to expanded fluids, compressed gas, or air. 

There you have it. Now you know a little bit more about the different kinds of compressors.  Are you confused as to which one is the best for you? Need further help making the connections between compressors and the cold room you’ve been looking at renting or buying?

If you need further information or help to understand your cold room or perhaps just want the guidance of a specialist, head on over to our website and get in touch today!