Project Title:

Sensor Performance Enhancements for Process-Control, Water-Quality Monitor for

92-1-12.02-2484                                                   NAS09-18851
Sensor Performance Enhancements for 
     Process-Control, Water-Quality Monitor for
Space Application
Astro International Corporation
100 Park Avenue
League City, TX  77573
E.L. Jeffers                                         (713-332-2484)

Abstract:

     The firm is developing a process-control, water-quality
monitor (PCWQM) for the Space Station Freedom, which measures the
potable water supply's temperature, conductivity, pH, iodine, and
total organic carbon content. The baseline design contains conven-
tional technology pH probes as limited life items. Newly developed
ion-selective, field effect transistor (ISFET) pH probes could
improve pH sensor life, reliability, maintainability, and accuracy
and enhance performance during long duration missions. The
baseline PCWQM design does not require turbidity measurement. Tur-
bidity, however, measures process water total dissolved solids and
is useful in detecting breakdown of water processor ion-exchange
bed or filter. This proposal has two objectives: 1) determine the
feasibility of using ISFET technology to improve pH measurement,
and 2) determine the feasibility of using compact, low-power,
nephelometer-based, solid-state, electro-optical technology to
measure turbidity.

Potential Commercial Application:

Potential Commercial Applications:  The process-control, water-
quality monitor can be used for aqueous cleaning solvents and
ultrapure water, agricultural sensors, real-time blood monitoring,
and oceanographic monitoring.

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