1. Air Conditioning
Compressors

2. Types of Compressors Rotary- Small appliances Screw- Large Chillers
Scroll- Central Air Conditioning; Newer Chillers
Centrifugal- Large Chillers
Reciprocating- Refrigeration and A/C Systems

3. Hermetic- Welded inside shell
Semi Hermetic- Bolted together and can be serviced
Open-Motor and Compressor are separate and are attached by a belt or coupling

4. Rotary
Small and light weight
Uses blades or vanes to move refrigerant

5. Operation Eccentric rotor (off center) Rotates inside cylinder
Suction and discharge are separated
Dome is on high side
Ports (tube stubs)

7. Advantages Efficiency is higher than a reciprocating type
Can pull a deeper vacuum
No dead head space
Less apt to blow fuses (trip breakers) on start up

8. Screw Compressor Used on large chilled water systems
Available in sizes 20 tons and up
Operation (helical screw compressor)
Refrigerant vapor is drawn into the space between the lobes of the screws
As the voids between the lobes gets smaller the gas is compressed and piped to the condenser
Screw compressors will operate smoothly even when capacity is reduced to as low as 10%

10. Scroll Compressors Newest type of Compressor
Has no intake or discharge valves except check valve on discharge.
The refrigerant vapor is squeezed
Very little wear and tear (few moving parts)
Two offset spiral discs to compress the vapor
Used in systems under five ton for now

13. Centrifugal Compressors
Used in large commercial refrigeration systems over 50 ton
Uses impeller or wheels
Vapor is moved in a circular path using centrifugal force
No valves or pistons
Operates at high speeds

16. Reciprocating Compressors
Domestic and Commercial use Compressors
Piston type
Normal RPM’s
Older units – 1725 RPM
Newer units – 3450 RPM

17. Hermetically sealed
Motor and compressor are sealed in a steel dome
External switching must be provided
Dome is on the low side of the system
Suction line ends at steel dome
Fills the compressor with low pressure low temperature vapor

18. Main Parts Cylinder Pistons Connecting rods Crankshaft Clylinder Head
Valves

22. Types of Reciprocating Compressors
Hermetic
Semi – Hermetic
Open

23. Hermetic (fully welded)
Sometimes called a tin can
Disposable
Cooled with suction vapor

25. Semi - Hermetic
Motor and compressor are contained inside a single shell that is bolted together
Can be serviced by removing bolts and opening
Air cooled as well as refrigerant vapor cooled
Sometimes water cooled

26. Motor and Compressor are separate. Connected by belt or coupling.
Open
Motor and Compressor are separate.
Connected by belt or coupling.