The local mounted enclosure (LME) on the Daniel Series 1500 Liquid Turbine Meter contains a standard dual-channel preamplifier and two variable reluctance pickoff coils. These coils have the sensitivity to provide accurate detection of rotor travel and have output with electrical characteristics of high impedance and low voltage. Noise-free transmission of the flow signals requires the opposite: low impedance and high voltage. This is the function of the signal preamplifier. Located within 16.4 feet (5 meters) of the pickoff coil, turbine meter preamplifiers shape and condition the pickoff output signal, rendering it suitable for transmission over distances of up to 3,000 feet (914 meters). Available Models Standard • The Model 2818 Dual Channel Preamplifier is the standard Daniel offering for most liquid turbine meter applications. The signals from two inductive pickoff coils, positioned 90° electrically out of phase, are strengthened and conditioned by a single preamplifier. Fully potted in POM (Polyoxymethylene), the Model 2818 preamplifier has three possible outputs: powered pulse, variable voltage and open collector. • The Model 2415 Intrinsically Safe Preamplifier is for hazardous area use (Zone 0). • The Model 1815B Zero Crossing Preamplifier produces an output pulse with each zero crossing of the input signal. It ensures high resolution, producing twice the pulses from a single pickoff. • The Model 1817X2 Bi-Directional Preamplifier is used on liquid turbine meters when the requirement is to accumulate flow in both forward and reverse directions.