Variable Area Flowmeter (VAF) with Two Switching Points
NCL and NCH switch types
NCH stands for "normally closed high" - when the top of the orange internal float is above the switch, the contacts will be closed.
NCL stands for "normally closed low" - when the top of the orange internal float is lower than the switch, the contacts are closed.
Most alarm systems operate on a "normally closed" basis - so when the alarm condition occurs, the contacts open, triggering the alarm. This acts as a fail safe in case the cable is damaged or broken as, detecting a break in the system, the alarm will activate.
If you require a different switching combination, please call us.