Copyright Goodheart-Willcox Co., Inc. May not be reproduced or posted to a publicly accessible website.. 98 Math for HVACR Weight Measurement Exercises The following exercise requires an electronic scale and a refrigerant cylinder. Refrigerant service cylinders are often designed to hold 30 pounds of refrigerant, but by AHRI and DOT Sta andards, they cannot be fi lled completely. Following the guidelines shown, calculate the allowable amount of refrigerant that can be held by a recovery cylinder for R-22. ▪ WC = 30 pounds ▪ SG of R-22 = 1.197 (at 77°F) ▪ TW = 17.1 pounds Exercise 5-5 1. How much R-22 can be held in this cylinder? __________ lb 2. If the maximum amount of R-22 is put into the cylinder, what will the total weight of the cylinder be? __________ lb 3. Using an electronic scale like the one shown earlier, weigh a refrigerant cylinder. Compare the e weight measured with the tare weight (the empty weight) printed on the cylinder. How much refrigerant is in your cylinder? __________ 4. Calculate how full the cylinder is. __________% 5. EPA regulations state that refrigeration systems containing more than 50 pounds of refrigerant must be repaired if the leak ratio exceeds 35% per year, calculated on an annualized basis. A system that holds 750 lb of R-22 has been leaking over the past y year. Every four weeks it needs to be refilled to capacity. Today, a technician added another 24 lb of refrigerant to the system. Calculate how much refrigerant this system leaks each year. __________ pounds 6. Based on the rule stated above, does the system’s leak ratio (loss of refrigerant) exceed 35% per year, thus requiring repair? __________