Vacuum exhausts from multiple pumps shall be permitted to be joined together to one common exhaust where the following conditions are met:
- The common exhaust is sized to minimize backpressure in accordance with the pump manufacturer's recommendations.
- Each pump can be isolated by manual or check valve, blind flange, or tube cap to prevent open exhaust piping when the pump(s) is removed for service from consequent flow of exhaust air into the room. [NFPA 99:5.1.3.7.6.5]