The United States has slowly been phasing out the use of R-22 refrigerant (or Freon), a Hydrochlorofluorocarbon (HCFC) refrigerant found in older commercial and residential HVAC equipment.

Regarding restaurant air balance, negative building pressure 

There is much hype these days in the facilities management industry about the importance of

Due to the skill level required and equipment needed, facility managers and mechanical contractors hire professional test and balance contractors to bring buildings into balance at the end of construction, remodels, ...

Understanding HVAC test and balance reports can be a challenge, especially for busy facility managers.