🔍 Key Concepts

• How refrigerant behaves in a closed cylinder (pressure vs. quantity) • What changes when refrigerant is added or removed from a cylinder • Which measurement is most reliable and commonly used for inventory control

💭 Think About

• If the cylinder is partly liquid and partly vapor, will the pressure change much as you add or remove some refrigerant at the same temperature? • Does the physical size of the cylinder change as you add refrigerant? How does that affect one of the possible measurements? • When technicians track how much refrigerant they have used on a job, what unit do they normally record in their paperwork?

✅ Before You Answer

• Think about which option is directly proportional to the actual amount of refrigerant present, regardless of temperature (hot day vs. cold day). • Consider which method is practically used in the field to know how much refrigerant is left in a service cylinder. • Eliminate any choice that depends strongly on temperature changes rather than true quantity of refrigerant.