Refrigerant Recovery Time and Phase Split

Recovery time is dominated by the vapor phase and by a large margin: a machine moving liquid in push-pull handles pounds per minute, while the same machine pulling the last vapor out to the required vacuum moves a fraction of that and slows further as pressure falls. Recovering liquid first, wherever the system and the machine allow it, is the difference between a ten-minute job and an hour-long one. The speed-up factor is the output that changes behavior, because setting up for push-pull or liquid recovery costs a few minutes of hose work and the calculation puts a number on how many minutes it buys -- which is what makes the argument on a hot roof at four in the afternoon. On a small charge the setup costs more than it saves; on a large one it saves the afternoon. A 45 lb charge taken 30 lb as liquid at 8 lb/min and 15 lb as vapor at 3 lb/min recovers in 8.75 min against 15.0 all-vapor, a 1.7 times speed-up, and the gap widens with charge size because the liquid fraction grows while the vapor tail stays roughly fixed: a 200 lb charge taken 170 as liquid is 31.3 min against 66.7, saving thirty-five minutes. The evacuation term is the tail and it is the part that cannot be rushed -- the rate falls as pressure falls, and stopping short is both a regulatory violation and a system left with refrigerant in it. A planning estimate; the recovery machine's rated performance, the required evacuation level, and EPA Section 608 requirements govern.

liquid_min = liquid_charge / liquid_rate; vapor_min = (total - liquid) / vapor_rate; recovery_min = liquid + vapor; total_min = recovery + evacuation; all_vapor_min = total_charge / vapor_rate; speedup = all_vapor / recovery.

Recovery time split by phase -- liquid at the machine's liquid or push-pull rate, vapor at its much lower vapor rate, plus evacuation to the required level -- by name, with the all-vapor case reported for comparison. Rates are the recovery machine's published figures, entered rather than bundled. The machine's rated performance, the required evacuation level, and EPA Section 608 requirements govern.

Time is charge divided by rate; the rates come from the recovery machine's own published performance and are entered by the user.

Estimate. AHJ and licensed professional govern.

Field names used by the API: total_charge_lb, liquid_charge_lb, liquid_rate_lb_min, vapor_rate_lb_min, evacuation_min, cylinder_net_lb, liquid_min, vapor_min, recovery_min, all_vapor_min, speedup_factor

• Vapor dominates vapor recovery runs at a fraction of the liquid rate and slows as pressure fallsrecovery machine performance
• Setup cost push-pull or liquid recovery costs setup minutes; worth it on a large charge, not on a small onerefrigeration service practice
• Evacuation cannot be rushed stopping short of the required level is a violation and leaves refrigerant in the systemEPA Section 608