Recovery-Cylinder 80% Fill
The maximum net refrigerant a recovery cylinder may legally hold under the 80% fill rule.
Example
You enter
- Cylinder water capacity WC (lb) 50
- Refrigerant liquid density (lb/gal) 9
- Refrigerant already in (net lb) 30
- Max fill fraction 0.8
You get
- Specific gravity 1.079
- Max net at fill limit 43.2 lb
- Remaining capacity 13.2 lb
- Percent full 69.5%
Checked against published worked examples from: ACHR News (Chris J. Ludwig), after AHRI Guideline K.
Details, formula, and sources
ScopeFrom the stamped water capacity and the refrigerant's liquid density, plus the headroom left and the fill / do-not-fill action.
Formula or tablespecific_gravity = density(lb/gal) / 8.34; max_net = 0.80 x water_capacity x specific_gravity; remaining = max(0, max_net - current). Do not fill when current >= max_net.
Source and editionDOT / AHRI 700 / EPA Section 608 recovery practice (by name).
Free accessThe 80% fill rule and the WC/tare basis are public refrigerant-handling practice.
What governsEstimate. AHJ and licensed professional govern.
API field nameswater_capacity_lb, refrig_density_lb_gal, current_net_lb, fill_fraction, specific_gravity, max_net_lb, remaining_lb, pct_full
- Fill fraction 0.80 maximum (the 80% rule leaves room for liquid expansion with temperature); never fill past itDOT / AHRI 700
- Net basis water capacity (WC) and tare are stamped on the cylinder; net = gross on the scale minus tare; 8.34 lb per gallon water basiscylinder stamp
- Handling never mix refrigerants; use only a cylinder rated and in-date for recovery; EPA Section 608 governsEPA 608