Emerson Process Management 760004-A User Manual

760004-A
February 2002

3-2     Operation                                                                         Rosemount Analytical Inc.    A Division of Emerson Process Management

Model NGA 2000 HFID

•  Power supply test - Verifies that all

internal DC voltages are within the
required tolerances.

•  Network test - Checks the internal

network interface.

•  20 bit ADC test - Checks the 20-bit

ADC on the Analysis Computer PCB
by sending a DC signal through the
Preamp PCB and reading the signal
back with the 20-bit ADC.

•  12 bit ADC test - Checks the 12-bit

ADC on the Analysis Computer PCB
by sending a DC signal and reading
the signal back with the 12-bit ADC.

•  Power Supply PCB test - Checks

the presence of the Power Supply
PCB by activating the 3-way air sole-
noid.

•  Safety PCB test - Checks the pres-

ence of the Safety PCB by sending a
command and reading it back.

•  Case temperature test - Compares

the temperature read between the
Preamp temperature sensor and the
case temperature sensor. They must
be within 10

°C of each other. This test

sometimes fails if the case is opened.
The sensor in the Preamp will take
longer to cool off since it is in an en-
closure. Re-running the self-test after
thermal equilibrium will produce a
positive result if the sensors are
working properly.

•  Oven/Sample Temperature test -

Compares the temperature read be-
tween the sample temperature sensor
and the oven temperature sensor.
They must be within 50

°C of each

other.

The self-test can be repeated at any time
by activating the TEST softkey in the Self
Test Results menu.

9.  Set the desired oven setpoint in the range

of 93

°C to 204°C (200°F to 400°F).

10.  Wait for the Purge Air green LED to illu-

minate.

11.  Introduce the remaining supply gases.

Perform leak check. (See Section 1-5
Specifications)

12.  Set and verify the internal gas pressures.

Burner Air

965 to 1103 hPa-gauge
(14 to 16 psig)

Fuel

1516 to 1723 hPa-gauge
(22 to 25 psig)

Sample
(non-adjustable)

206 to 290 hPa-gauge
(3.0 to 4.0 psig)

Purge air of the following specifications
must be present:

Flow:  16 to 18 L/min.

Supply Pressure:  689 to 1378 hPa-gauge

       (10 to 20 psig)

Noncompliance could cause damage to
the module. At the very least, the mod-
ule's safety system, which requires a
certain volume of purge air flowing
through the case before allowing burner
ignition, will not allow the instrument to
operate. The lowest purge air
flow/pressure setting possible during
burner operation is preferable. Thus, the
user should set the external purge air
pressure initially at 689 hPa-gauge (10
psig). Check the Miscellaneous Control
Parameters screen under Technical Di-
agnostics, and note whether the Purge
Gas (switch) variable is "ON." If it is
"OFF," increase purge air supply by
69 hPa-gauge (1 psig), and recheck the
Purge Gas variable until it reads "ON."
DO NOT EXCEED 1378 hPa-GAUGE (20
PSIG). If the maximum setting is reached,