Copeland Scroll™ 

Due to the fact that low-temp scrolls are adaptable for use on high, medium, and low temp applications, authorized wholesalers will stock this model for use on all equipment. Specification sheets with compressor rating data (amps, capacity, watts, and mass flow) are also available at your local PrimeSource Wholesaler or can be found in our Online Product Information (OPI) database.

Compressor mounting must be selected by application, with special consideration given to sound reduction and tubing reliability. Use hard mounts for multi-scroll racks, and soft mounts for single scroll units.

As with all compressor types, it is important to monitor and control pressure and temperature in refrigeration scroll applications. A discharge line thermostat is required on all models from 2 to 6 hp. It is set to shut off the compressor at 125°C (250°F) or less. The thermostat must be insulated if the application is outdoors. It should also be located 12.5 cm (5 inches) from the discharge connection to the compressor. Both high and low-pressure controls are required. The low-pressure control is required for protection against deep vacuum. This can result in arcing of the internal electrical connections and cause permanent damage to the compressor.

Scrolls handle liquid better than most other compressor types, but still can require additional accessories for optimal protection. Those accessories include: Accumulators are recommended for systems with large refrigerant charge or those that allow for uncontrolled refrigerant floodback. Crankcase heaters are required for three-phase systems with large refrigerant charge and in/outdoor applications.

Refrigeration scrolls operate with either liquid or vapor injection, making a wider operating envelope available. The liquid injection function feeds a steady flow of liquid to the middle of the scroll compression cycle to cool compressor components. This does not affect the compressor's performance as it would a reciprocating compressor. Injection is controlled by a liquid solenoid valve and cap tube metering device which feeds more liquid as head pressure rises. A current sensing relay is also required if the charge exceeds 4.5 kg (10 lbs.). It will stop the flow of liquid if the overload protector trips. Liquid injection is the simplest to pipe and the lowest-cost option, and it can be used any time refrigerant injection is required.

On rack applications all compressors require the use of an oil management system to maintain proper oil level in the compressor crankcase. Unlike reciprocating compressors, scroll oil pumps do not have accompanying oil pressure safety controls; instead, they require an external oil level control. The control should combine the functions of oil level control and timed compressor shut-off should the oil level not come back to normal within a set period of time. Immediately after the system start-up, the oil reservoir level will fluctuate until equilibrium is reached. You should carefully monitor the oil level during the first 24 hours to assure sufficient oil is available and to prevent any unnecessary trips of the oil control system.

Copeland Scroll refrigeration compressors used on multiple compressor racks must use oil separators and oil distribution systems similar to those used for semi-hermetic racks. However, they do not have positive displacement oil pumps like those found on most semi-hermetics. So there is no way to measure oil pump pressure as an indication of adequate lubrications. To protect Copeland Scroll refrigeration compressors against a lack of oil, you must use a float type system to sense the oil level in the compressor pump. If the oil level drops below a preset value, oil must be admitted to the compressor from the reservoir supplied by the separator. If the level remains below that preset level for a specific amount of time, the control will turn the compressor off. The TraxOil® is an example of a system that works well with Copeland Scroll refrigeration compressors in multiple compressor racks. (TraxOil is a registered tradename of TraxOn International.)

Copeland Scroll refrigeration compressors (such as ZBxxKA-PFV) are designated by a "Z" in the first position of the model number. The second position determines the application range (B = high/medium temperature, S = medium temperature, F = low temperature). The third and fourth positions represent the first two digits of the capacity of the compressor at its standard rating conditions and the fifth position gives the multiplier for the capacity (C = 100, K = 1,000, and M = 10,000). The sixth position designates the compressor's model generation. If there is a seventh position before the dash prior to the electrical designation, it will be an E (Polyol Ester oil) or an L (shipped less oil). If there is nothing in the seventh position, the compressor has mineral oil in it. Electrical designations (such as PFV) are the same as other Copeland® models. For picture diagrams, go to our Online Product Information (OPI) database on this website and search nomenclatures by product category. Copeland Scroll refrigeration compressors shipped with mineral oil are only approved for R-22. However, models shipped with Polyol Ester or less oil are approved for use with R-22, R-404A, R-507, and R-134a.

At first glance, refrigeration scroll compressors look very much like their air conditioning counterparts. But these two products are really quite different. Refrigeration scrolls undergo a number of design changes before they can meet the distinct performance demands of commercial refrigeration equipment. For example, you won't find liquid injection capability or an oil sight glass on an air conditioning scroll compressor.

Copeland Scroll compressors are direction-dependent, meaning they will compress in just one rotational direction. Three-phase scrolls will rotate in either direction, depending on power phasing. Here, the service technician should be aware of potential problems associated with reverse rotation. Prolonged operation in reverse result in insufficient lubrication, scroll galling and scroll set damage. Look for the following signs to verify reverse rotation:

1. Discharge and suction pressures do not change

2. Noisy operation (note: noise at shut down is a sound issue only; it will not cause damage)

3. Current draw is substantially reduced compared to tabulated values

4. If it is a three-phase scroll, determine the proper rotation at start up by observing that the suction pressure drops and discharge pressure rises. In addition, a phase monitor is recommended to eliminate the possibility of reverse rotation. Larger scrolls (7.5 to 15 hp) incorporate a phase monitor and timed lockout control in the motor protection module to protect against reverse rotation and power interruptions. For single-phase compressors, a timed lockout control is recommended in case there are brief power interruptions.

Copeland Scroll's compliant design provides both axial and radial compliance between scroll members, increasing compressor life. "Compliance" is the ability to separate under abnormal conditions. This feature eliminates interference contact, which can cause breakage. Axial compliance allows the scroll to remain in continuous contact in all normal operating conditions, ensuring minimal leakage without the use of tip seals. Radial compliance allows the scroll members to separate sideways so debris can pass through, substantially improving durability and reliability. The combination of axial and radial compliance result in the scrolls actually "wearing in" rather than "wearing out". Continuous flank contact, maintained by centrifugal force, also minimizes gas leakage and maximizes efficiency of the compressor.

Two, spiral-shaped members fit together, forming crescent shaped gas pockets. One member remains stationary, while the second orbits relative to the first. As the spiral movement continues, gas is drawn in and forced toward the center of the scroll form, creating increasingly higher gas pressures and discharging the gas from the port of the fixed scroll member. Visit the scroll technology page for additional information and to watch an animated scroll demonstration.