Optimal placement of condenser in butane vapor recovery

Hello, thanks in advance for your suggestions. After some downtime and passive runs, I put my rebuilt trs21 back into action. After coming to the shop I noticed my employee had placed the condenser at the input of the pump instead of the output. After some questioning he claimed after multiple runs everything was running smoothly.
but the filter drier (https://www.bestvaluevacs.com/bvv-filter-drier.html) on the inlet of the pump was developing a frost. Another colleague suggested returning to the previous configuration. Where is the optimal placement of the condenser? Should the pump be pulling through the condenser and sending liquid through the pump or pushing vapor through it and sending liquid to the manifold? Im curious what everyone here thinks.

my understanding is that the trs21 will be happier pumping gas, as that was what it was designed to do. I have it in the back of my head that some recovery pumps can get quite pissed off at liquid refrigerant (broken rods or blown seals). I recall a manufacturer telling me that it was the first few slugs of liquid butane that were the most likely to cause an issue. don’t recall which manufacturer. I may even be hallucinating. :slight_smile:

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thanks for the input, but i checked the manual and it looks like its fine pumping liquid. in fact it gave several configurations for pumping liquid. http://www.cpsproducts.com/wp-content/uploads/TRS21-Series_Product-Manual.pdf
in case anyone is interested

hallucinating again it is…glad you know the importance of rtfm.

The hammering mentioned in the manual sounds much like the vague memory I have of “pissed off”…

Note: Recovery Unit is designed to directly recover large amounts of liquid refrigerant. During Vapor Recovery, if compressor makes slugging or hammering noise, meter incoming liquid refrigerant by closing LOW Side Manifold Valve until noise subsides.

Liquid doesn’t compress like gas does, which is what the hammering is about. Maybe it was a repair guy…

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my eyes jumped to that exact passage, but i noticed the way my employee had everything setupa, he wouldnt have any way of adjusting the flow because the liquid is starting on the wrong side of the manifold. when compared to the picture included in the manual.

What did you end up figuring out? If
you don’t mind me asking…

Every rig I have ran the condenser goes after the recovery pump unless you’re doing a cold injection . Most are designed to pump in a vapor form and the pump also will heat it up significantly (unless its air driven) so you want to condense going back to the solvent tank .

heat removal after compression.
liquid in your vapor recovery pump causes a few issues.

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