how many diffusers per square foot?
A diffuser airflow rate is 50 cfm per linear foot (77.4 L/s per linear meter) of diffuser. Therefore, the recommended flow to use when designing is 50 cfm/ linear ft x 0.8 = 40 cfm/linear ft (77.4 L/s/ linear m x 0.8 = 61.9 L/s/linear m). The nominal airflow of a diffuser is determined by multiplying the diffuser length, the number of slots, and the airflow per linear foot. Using the airflow per linear foot calculated above, a 4 foot, 2-slot, 2-way diffuser should be designed to handle 4 linear ft x 2 slots x 40 cfm/linear ft = 320 cfm (1.219 m x 2 slots x 61.9 L/s/linear m = 150.9 L/s). To maximize the effectiveness of ventilation with ceiling diffusers, throws should be kept as long as possible.