HygroTrace Moisture Transmitter
1
September 2007
Introduction
The GE Sensing
HygroTrace
is a compact moisture transmitter
designed for measuring ultra-low water content in the ultra high
purity and semiconductor markets and related applications. The
HygroTrace
measures water content in nitrogen or argon gas in
the range of 0 to 100 ppb
v
with trending analysis beyond the
calibrated range. The unit features an integrated display and a six-
button keypad, and is housed in an aluminum enclosure. The
HygroTrace
operates on 24 VDC and provides 4-20 mA analog
and RS485 digital outputs.
The
HygroTrace
uses an aluminum oxide sensor manufactured
with semiconductor techniques. The patented measurement
technique enables the
HygroTrace
to respond very quickly to
both dry-to-wet and wet-to-dry situations. The technique applies
a temperature pulse to ‘dry’ the sensor. Then, the re-adsorption
rate is measured while holding a constant sensor temperature.
This measurement is proportional to the moisture concentration
in the sample gas. As a result, the
HygroTrace
offers the
sensitivity and response time needed to effectively measure parts
per billion levels of moisture.
Installation
Sample System Guidelines
The
HygroTrace
transmitter is typically installed in a sample
system or on the bypass stream of an ultra-high purity gas
distribution system. The factory recommends that the unit be
installed in a sample system to protect the sensor from coming in
contact with damaging elements in the process, and to allow the
transmitter to be removed for service without interrupting the
main process gas flow.
Before constructing a sample system, consult a GE Sensing
applications engineer and adhere to the guidelines below. See
Figure 1 on page 2 for an example of a sample system.
