Which statement is true when pumping down a scroll compressor?

When pumping down a scroll compressor, operating the unit in low speed for less than 1 minute is considered effective practice. This approach helps to maintain the integrity of the compressor while achieving the necessary suction without placing undue stress on the components. The low speed ensures smoother operation and reduces the risk of overheating or damaging the compressor during the pump-down process. It allows for a gradual reduction in pressure, which is essential for maintaining system safety and efficiency.

In contrast, operating at high speed can lead to rapid changes in pressure that may not be beneficial during the pumping down process. Additionally, discharge valve plates are designed to seal under pressure; however, the focus in this scenario is on proper technique rather than their specific behavior under pumping conditions. While there may be elements of truth in the other statements, the emphasis on the low-speed operation for a limited duration most accurately reflects best practices when pumping down a scroll compressor.