We finalized our recovery with our recovery machine pulling a light vacuum on the systems. Our first step working with the empty systems was to drain all the refrigeration oil that could be freely drained from the Parker POR reservoirs and compressor sumps. This simple gravity-drain procedure removed the majority of oil from our systems, though we knew that there would be some oil trapped in areas that cannot readily be drained. We will deal with removal of the remaining oil in our next post. Since R404A and R448A both require POE oil, multiple changes with flushes as would be required if we were retrofitting an HCFC/mineral oil system, are not needed.

Filter changes were the next order of business. Oil filters were changed first, with new Sporlan OFE-1 cartridges installed in ROF-413-T filter housings. The coalescing filter elements in the oil separators were also changed. We then moved on to changing compressor suction filter elements. New RPE-48-BD pleated suction filters were placed in RSF-4813-T housings. There is one suction filter per compressor on our systems. Each rack has a replaceable-core Catch-All to filter and dry the liquid supply into the liquid header. The Catch-All cores were replaced with new RC-4864's.

Now is also the time to replace valves, seals, and other components on the "shopping list" we made in preparation for our retrofit. We determined that we did not need to replace any valves in our preparatory work, primarily because we had EEVs installed at the time. Our systems were already equipped with Sporlan Y1037 liquid injection valves. Had they not been, we would have installed them at this time so that we could maintain acceptable discharge temperatures with R448A.

We sealed the systems back up carefully, making certain to use new seals on all filter housings, and properly torquing the cover bolts. At this point we were ready to begin leak checking, which we will cover in our next post.
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