MODEL SMD SPECIFICATIONS Automatic Reset Differential • Vacuum PressureMaximum PressureSurge: 20” W.C. Ambient Temperature:-40°F to 170°F CONNECTION Comp. Fittings 1/8” NPT 1/4” Hose Barb RANGES w.c. mm/w.c. .17”-6” 4.25-100 .17”-6” 4.25-100 .17”-6” 4.25-100