The Walchem WECT400-142U controller is now obsolete and the closest equivalent is the WCT600 controller. The new WCT600 series has upgraded features; for reference, here is the description of the old model:
Cooling tower controller – bleed & feed, 120 VAC, prewired, single isolated (4-20 mA) output, electrodeless conductivity sensor & flow switch manifold on pp panel, 5 ft cable, data logging and configuration file capability.