Table of Contents
Advertisement
The remaining three flow paths are supplied with sample gas by a proportional
solenoid valve (PSV), which is used to regulate the flow of gas through the
analyzer. Downstream of the PSV, the remaining three flow paths separate.
•
•
Solenoid Valves
The three-way solenoid valves (SV2, SV3, SV4) are used to select the gas
stream that is passed through the Sensor; the remaining two streams are
passed to the vent. The two-way solenoid valve (SV5) is used to isolate the
dryer from moisture when power is removed from the analyzer. In normal op-
eration of the 5830, the analyzer continuously cycles between the Sample- and
Dry-Reference gas streams. This switching action modulates the water vapor
concentration to which the Sensor is exposed. As such, the resonant frequency
of the Sensor crystal is modulated, decreasing as the Sensor is exposed to the
water vapor in the sample stream, and increasing as the Sensor is exposed to
the Dry-Reference gas. The role of the permeation device (Moisture Generator)
is to provide an on-board means of checking the performance of the QCM Sen-
sor. In the "generator mode", the QCM Sensor is alternately exposed to the gas
stream from the Moisture Generator and the Dry-Reference stream.
PN 583054901, Rev YA
Path 2 goes directly through a capillary tube, and on to a three-way sole-
noid valve (SV2).
Paths 3 and 4 branch after the sample gas is passed through a dryer. The
fourth flow path contains a small moisture permeation tube. Thus,
-
a portion of the flow through the analyzer is a bypass,
-
a portion of the flow is passed directly to the QCM Sensor assembly
(the sample leg),
-
the third portion is dried before passing to the QCM Sensor (the Dry-
Reference leg), and
-
the fourth flow path dries the gas and adds a controlled amount of
water vapor to the stream (the "Moisture Generator" leg).
|
Overview
1-7
Advertisement
Table of Contents
