Charging a plant
The correct charge is the figure on the maker’s nameplate or in the plant manual. After a repair, recovered refrigerant is weighed back in and the shortfall is added as new gas. Liquid charging into the receiver is the usual method when the plant is stopped. Never vent refrigerant to the atmosphere. MARPOL and company rules require recovery.
How this calculator works
Still required = Nameplate − Remaining − Already added. A negative figure means the plant would be overcharged. Sight-glass, pressures and superheat still decide whether the charge is right in service. Weigh cylinders before and after. Record the type and quantity in the ozone / refrigerant record book.
Who should use it
Useful for engineers weighing gas back into a provision or AC plant. Follow the maker’s procedure and use recovery equipment.