4 Operation
Model 3000MB
4-12
Teledyne Analytical Instruments
for the first
Slope
value to display.
Slope
indicates rate of change of the
Span
reading. It is a sensitive indicator of stability.
#### % Span
Slope=#### ppm/s
When the
Span
value displayed on the screen is sufficiently stable,
press
Enter
. (Generally, when the
Span
reading changes by 1 % or less of
the full scale of the range being calibrated for a period of five minutes it is
sufficiently stable.) Once
Enter
is pressed, the
Span
reading changes to the
correct value. The instrument then automatically enters the
Analyze
func-
tion.
4.5
The
Alarms
Function
The Model 3000MB is equipped with 2 fully adjustable concentration
alarms and a system failure alarm. Each alarm has a relay with a set of form
“C" contacts rated for 3 amperes resistive load at 250 V ac. See Figure in
Chapter 3,
Installation
and/or the Interconnection Diagram included at the
back of this manual for relay terminal connections.
The system failure alarm has a fixed configuration described in chapter
3
Installation
.
The concentration alarms can be configured from the front panel as
either
high
or
low
alarms by the operator. The alarm modes can be set as
latching
or
non-latching
, and either
failsafe
or
non-failsafe
, or, they can be
defeated
altogether. The setpoints for the alarms are also established using
this function.
Decide how your alarms should be configured. The choice will depend
upon your process. Consider the following four points:
1. Which if any of the alarms are to be high alarms and which if any
are to be low alarms?
Setting an alarm as HIGH triggers the alarm when the oxygen
concentration rises above the setpoint. Setting an alarm as LOW
triggers the alarm when the oxygen concentration falls below the
setpoint.
Decide whether you want the alarms to be set as:
•
Both high (high and high-high) alarms, or
•
One high and one low alarm, or
•
Both low (low and low-low) alarms.
2. Are either or both of the alarms to be configured as failsafe?
