Teledyne 2000A-EU - General purpose thermal conductivity analyzer - Manual (Page 54)

4 Operation Model 2000A-EU
4-16 Teledyne Analytical Instruments
Once the span has begun, the microprocessor samples the output at a
predetermined rate. It calculates the difference between successive samplings
and displays this difference as Slope on the screen. It takes several seconds for
the first Slope value to display. Slope indicates rate of change of the Span
reading. It is a sensitive indicator of stability.
##### % O2 — Air
Slope=#### Span
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 range
being calibrated for a period of ten minutes it is sufficiently stable.) Once Enter
is pressed, the
Span reading changes to the correct value. The instrument then
automatically enters the Analyze function.
4.5 The Alarms Function
The Model 2000 is equipped with 2 fully adjustable concentration alarms
and a system failure alarm. Each alarm has a relay with a set of form “C" con-
tacts 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
contaminant concentration rises above the setpoint. Setting an
alarm as LOW triggers the alarm when the contaminant
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?