What is cost difference between ppgl and and ppgi sheet?

What is the definition of cold room?

The PPGI Steel Sheet Cold Storage is intended for cooling and storage of perishable product-cooled or frozen.1. The sandwich panel for the cold room is built by polyurethane, easy to mount and to disassemble or enlarge if necessary.2. The panels are joined through quick-action eccentric mechanisms. 3. The external and inner panel cover is of a zinc-coated steel sheet with a plastic finish. The heat insulation is of rigid foam polyurethane.3. The floor panels are reinforced and they withstand distributed load up to 2000 kg / SQ Meters.4. Cold Storage is equipped with electric lighting. Freon 22 and 404A are used as refrigerants.5. The prefabricated cold rooms are intended for cooling and storage of perishable products-cooled or froze.6. The Cold Storage should be installed in a sheltered place away from direct sunshine, dust, and rain.7. Depending on the cooling temperature maintained, the Cold Storage can be:　- for medium temperatures from + 20℃ to -5℃.　- for low temperatures from -15℃ to -60℃.8. According to the conditions of work the Cold Storage is available from +5℃ up to + 45℃ ambient air temperature.Yuyan-refrigeration is a professional manufacturer of a\cold room.