Water Analytics manufactures four models of liquid level controllers to satisfy most industrial applications. These controllers operate on the principle of electrolytic conductivity in liquids. A built-in sensitivity adjustment permits field tuning the instrument so that one model is suitable for most conductivity liquids. For instance the LL4 or LL7 may be adjusted to respond to either foam or liquid. Some controllers may be as far as 300 meters from the electrodes, and connections are made with unshielded cable.

The AquaMetrix design limits the voltage at the electrodes to 18 volts, and also limits the current even if electrodes are shorted. Some competitive controllers may require as much as 500 volts across the electrodes.

The LL4 has one relay for a pump with normally open or normally closed operation. The LL7 and LL7H have the added feature of an auxiliary pair of normally open contacts for use with an annunciator or other device. The LL7 version is suitable for most industrial applications. The LL7H has much greater sensitivity and is specifically designed for use with low conductivity liquids.

This LL3 is the most versatile of the four LL Series controllers. It contains two relays, for pump and auxillary use, each with normal open or normal closed operation. An indicator LED light in the unit can be used for very accurate sensitivity adjustments.

All LL Series controllers are suitable for single level service or differential service. Single level service allows for high or low alarm, while differential service provides a pump up/pump down region between two electrode heights. All units are housed in a NEMA 1 black ABS plastic enclosure which plugs in to a standard 12-pin relay socket with durable screw terminals. The pins and terminals are nickel plated brass.