If oil is returning poorly to a compressor with a double riser, which riser should have its capacity checked?

In a refrigeration system utilizing a double riser, one of the risers is typically designed to carry a larger volume of vapor while the other is smaller and often responsible for returning oil. If oil is having trouble returning to the compressor, the smaller riser should be the focus for capacity checking.

This is because the smaller riser's capacity is directly related to its ability to carry oil back to the compressor efficiently. Insufficient capacity in this riser could lead to inadequate oil flow, contributing to lubrication issues within the compressor and potentially causing serious operational problems. By evaluating and ensuring that the smaller riser is functioning properly, you can help restore correct oil return and maintain the system's overall efficiency and reliability.

Monitoring both risers may seem logical; however, focusing on the smaller riser directly addresses the issue of oil return specifically, which is crucial in preventing compressor damage and ensuring proper lubrication.