The Walchem WDB300-145 controller is now obsolete and the closest equivalent is the WBL600 controller. The new WBL600 series has upgraded features; for reference, here is the description of the old model:
Four powered relays (two blowdown & two feed/alarm), 120 VAC, prewired, single isolated analog (4-20 mA) output, two standard electrodes (up to 250 psi)
