Which statement is true regarding the compression ratio of a reciprocating compressor?

The statement that the compression ratio of a reciprocating compressor varies according to operating conditions is accurate because the compression ratio is defined as the ratio of the volume of gas before compression to the volume after compression. As operating conditions change—such as variations in pressure, temperature, or gas properties—the volumes involved in the compression process can also change, thereby affecting the compression ratio.

In practical applications, factors such as suction pressure, discharge pressure, and even the nature of the gas being compressed can lead to variations in performance and, correspondingly, in the compression ratio. This characteristic is essential for understanding how a compressor will perform under different load conditions, which can help in optimizing system efficiency and ensuring appropriate operational settings.

The other statements do not accurately reflect the nature of compression ratios in reciprocating compressors. For instance, stating that it is constant regardless of operating conditions does not consider the dynamic behavior of the compressor under varying loads. Similarly, saying it only depends on pump design overlooks the significant influence of operational variables, and asserting that it should always be above a specific ratio does not account for the diversity of applications and designs in the field of compression technology.