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7. System application
7.1 Overview
The content of this chapter is proposed for the reliable and safe operation of the RFC
screw compressor, if there is any violation of the principles, suggestions or questions
mentioned in this chapter. Please contact RFC first!
For screw compressors, users can compose a system in a similar way to piston
compressors. It's just that the oil circuit has its particularity and needs special attention.
Due to the structural characteristics of the screw compressor itself, it is not sensitive to
liquid compression during operation and shows good reliability. However, measures should be
taken to ensure that the compressor will not be filled with lubricating oil or refrigerant liquid
during the shutdown period. Filling the compressor with lubricating oil or refrigerant liquid will
cause uncontrollable liquid pressure during startup, and in extreme cases, the bearing will be
damaged. , the compressor itself and the solenoid valve of the oil circuit, etc.
Compressors must be protected against contamination such as dirt (dirt, rust and
phosphate deposits). The cleanliness of oil and refrigerant during compressor operation has a
major impact on the reliability and life of the compressor.
7.2 general principles
Determination of pipe diameter and oil return
For the short circuit pipeline, the diameter of the pipeline is mainly determined by the
nominal size of the globe valve. However, for pipelines with multi-branch systems, such as
low-temperature systems, parallel systems, systems with large load changes, and the
ascending section of the pipeline, special calculation dimensions are required. The usual
calculation criterion is to determine the pipeline according to the flow rate (oil return). diameter.
Considering the flow rate of oil in the return pipe, the airflow velocity in the horizontal pipe
should be ≥4m/s, and the airflow velocity in the vertical pipe should be ≥8m/S.
For the longer riser pipe, an oil trap should be set every 4m (the length of the oil trap
must be as short as possible to avoid excessive oil accumulation); while for a single
compressor (or parallel system) partial load operation, it should be set Double riser to ensure
oil return. Figure 7-A
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