MKS MKSINST IE1000A, Инструкция по эксплуатации

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Zeroing the MKS IE1000A High Flow Rate Mass Flow
Controller Chapter Four: Maintenance and Troubleshooting
34
Preparing to Execute Zero Adjustment
Zeroing a flow sensor at a real flow above its stated minimum resolution creates a zero flow offset relative to
the true absolute zero flow. All subsequent readings are then linear and accurate relative to the offset value.
1) Verify that the MFC is setup in the exact process conditions:
a)
Verify that the MFC is installed in the process gas line properly in the orientation orientation of use
(base down (HBD), vertical flow up (VID), vertical flow down (VIU), etc.)
b) Verify that the MFC is powered at operating temperature for at least one (1) hour 30 minutes.
c) If the MFC will be subjected to elevated ambient temperature conditions, verify that these
temperatures have been achieved and stable for at least one (1) hour before continuing.
2) Verify that the pressure drop across the MFC is reduced to zero. Depending on the gas panel
configuration, this may be done by one of the following procedures.
OPTION 1: SYSTEM HAS UPSTREAM & DOWNSTREAM ISOLATION VALVES
Zero the MFC at typical operating inlet pressure.
a)
Close the upstream isolation valve.
b) Close the downstream isoaltion valve.
c)
Open the MFC’s control valve.
d) Allow pressure across MFC to equilibrate as flow output approaches zero and stabilizes.
e)
Close the MFC’s control valve.
f) Wait one minute and adjust the zero using one of the methods specified for the device I/O type later
in this section.
OPTION 2: SYSTEM HAS DOWNSTREAM ISOLATION VALVE ONLY
Zero the MFC at typical operating inlet pressure.
a)
Close the downstream isolation valve.
b)
Open the MFC’s control valve.
c) Allow pressure to equilibrate across the MFC as flow output approaches zero and stabilizes.
d)
Close the MFC’s control valve.
e) Wait one minute and adjust zero using one of the methods specified for the device I/O type later in
this section.
OPTION 3: SYSTEM HAS UPSTREAM ISOLATION VALVE ONLY
Zero the MFC at atmosphere or vacuum conditions.
* NOT RECOMMENDED FOR ORIENTATIONS OTHER THAN HORIZONTAL BASE DOWN
a) Close the upstream isolation valve.
b)
Open the MFC’s control valve.
c) The MFC may be evacuated to vacuum or exposed to atmosphere on downstream side. For either
case, the downstream pressure must be kept constant to insure there is no pressure drop across MFC.
d) Allow pressure to equilibrate across MFC as flow output approaches zero and stabilizes.
e)
Close the MFC’s control valve.
f) Wait one minute and adjust zero using one of the methods specified for the device I/O type later in
this section.
IE1000A Executing Zero Adjustment
To perform the flow zero adjustment, use one of the listed techniques specific to the interface type of the
IE1000A High Flow Rate Mass Flow Controller
15-pin analog IO Mass Flow Controllers
OPTION 1: Analog Interface (15-pin only)
a)
Pull Pin 9 to ground for three (3) seconds.