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Fig. 1. Diagram of the polarographic sulfide sensor, PSS. A side view and expanded
tip view of the PSS illustrates the component parts. The overall dimensions
are 25 mm long and 12 mm diameter, with individual components proportionally
sized. The sawtooth lines indicate threaded pieces. The platinum anode and
cathode are cemented into the polyether ether ketone (PEEK) housing with epoxy
resin. The membranes are cemented together with silicone cement. The 0.5 mm
hole in the H2S-impermeable membrane is concentric with the anode
and provides a small reservoir of electrolyte between the anode and the
H2S permeable membrane. Lateral diffusion of H2S from
this region at the tip into the bulk electrolyte is limited and greatly
shortens response time as the impermeable membrane serves as a virtual guard
ring.