Morrison Combination Vent/Overfill Alarm

The 922 Combination Vent/Overfill Alarm is a fully mechanical, high intensity audible alarm that alerts you when your tank is near full while also allowing your tank to breathe during filling and dispensing operations. The unit is equipped with a whistle that incorporates a 2” or 3” full port pressure/vacuum vent. The unit can be set to activate at 90% fill height by adjusting the cable length to the float device. The adjustment tool is provided. The unit attaches to a 2” or 3” N.P.T. pipe mounted on the tank. Minimum fill rate for alarm to operate is 20 GPM.Combo-Vent-Overfill-Alarm.jpg

Construction Details

Body:         anodized aluminum
Screen:        stainless steel
Rainguard:    anodized aluminum
Seal:        Viton®
Ball:        Teflon
Float:        stainless steel

2” Pressure relief setting ...... 6 oz/in2 or 8 oz/in2
2” Vacuum relief setting....... 1 oz/in2
2” Venting capacity (CFH) ... 30,120 or 30,300

3” Pressure relief setting ...... 6 oz/in2 or 8 oz/in2
3” Vacuum relief setting....... 1 oz/in2
3” Venting capacity (CFH) ... 43,020 or 44,160Combo-Vent-Overfill-Alarm-Illustration.jpg


In order for the 922 Combination Vent/Overfill Alarm to function properly all emergency vents, fill connections, tank openings and piping connections must be airtight. Emergency vent should be set at least 2oz. higher than the 922 Combination Vent/Overfill Alarm. All storage tank vent air passages must be completely free of restriction and all vent mechanisms must have free movement in order to insure proper operation.