Validyne AP10 sensors on a DC-powered test stand: CD16 vs CD18/MC1, and the range codes

Facts checked on Validyne pages (Nov 2026): - Range codes (Diaphragm Range Code Chart, p. 2): 52 = 200 psi, 54 = 320, 56 = 500, 58 = 800, 60 = 1250, 62 = 2000. The dash number on an AP10 (e.g. AP10-58) is only the diaphragm range; it is the same sensor body, not a cryogenic or special variant. - AP10 product page: overpressure is the greater of 20 psia or 200% of full scale; all-stainless wetted parts; no o-rings or gaskets inside the unit; Validyne lists the CD15 and CD16 demodulators for it. The pressure port is a 5/16-24 straight thread (O-ring boss), so the adapter seals on an O-ring; choose one compatible with your medium (avoid Buna-N for oxygen). - CD16: single channel, unregulated 9 to 55 Vdc supply, 0 to +/-5 Vdc output (an absolute sensor then reads 0 to +5 V), 5 kHz square-wave excitation, zero and span via case access holes, 4-20 mA and isolated versions available. Frequency response is not stated publicly: ask. - CD18: needs +/-15 V from an MC1 module case; outputs +/-10 V; DC to 250 Hz standard (1 kHz option). The MC1 cases come in 3, 10 or 20 slots; the 3-channel MC1-3 is a bench-top case with its own supply. Practical takeaway: if the stand offers 24 V DC and a 0-5 V DAQ, one CD16 per sensor is the simpler fit (no case, no AC, no rescaling). It also scales past three channels. Pick each range from what the point must read in normal running, then check that 2x full scale covers the worst pressure it can see (blocked flow, relief settings, purge). Keep sensors on a long thin stainless standoff so they stay near room temperature on cryogenic lines.