The switch should be adjusted so that it activates within 2 complete turns of the valve. We typically shoot for 1-1.5 turns. Anything less than a complete turn is asking for possible vibration issues and intermittent tripping. The first 1/8 to 1/2 turns of some valves, is nothing more than thread slack. You may also try a plug-style tamper switch to see if the "ghost-supervisories" go away. A typical example would be the Viking PTSC tamper switch. Also, we have noted that anything other than "Aquaseal" type wires tend to have moisture related triggering issues over time. Hope this helps.

Tj Johnston
VSC Fire & Security