Operation And Stabilization; Power Up And Warm Up; Stabilization; Perform A Manual Zero - Emerson MRLDS-250 Installation And Operation Manual

4 Operation and

Stabilization

4.1. Power Up and Warm
Up
On powering up, the MRLDS-250 will sense for
the presence of gas after an initial warm-up period of
two (2) to five (5) minutes. The green LED will flash
at a one-second interval during the warm up.
4.2. Stabilization
CAUTION: It is vital when first installing the
gas detector that it warms up in an atmosphere
that is known not to contain any background
concentrations of refrigerant. Emerson Retail
Solutions offers portable gas detectors for this purpose.
Contact Technical Support for more information.

4.3. Perform a Manual Zero

After the gas detector stabilizes, the power LED
stops flashing and is illuminated continuously.
Emerson Retail Solutions recommends manually
zeroing the MRLDS-250 after a 1-hour stabilization
period.
To manually zero the gas detector, press and hold
the UP and DOWN buttons simultaneously for five
(5) seconds. The gas detector will beep and the
display will show "zEro" when zeroing is complete.
The display will show "fAiL" if the temperature is
changing too quickly or there is an active alarm
condition.
NOTE: A manual zero should be performed in
the environment of operation and at the typical
operating temperature.
10 • MRLDS-250 Gas Detector Manual
NOTE: Subsequent manual zeros may be
performed, provided the atmosphere around
the gas detector is free of all background
concentrations of refrigerant. Clean air or
nitrogen applied to the calibration port for five (5)
minutes may be used to ensure the gas detector is clear
of all background gas. Re-zeroing with background
refrigerant present will cause the gas detector to report
incorrect readings.

4.4. Alarms

The following occurs during an alarm condition:
Item Behavior During Alarm State
Green On (solid)
LED
Display On (blinks); reports detected PPM
concentration
Audible On (if enabled and after programmed delay
Alarm
expires)
Relay Activates (after any programmed delay
expires)
Output
Analog Changes proportionally with gas
concentration (as configured)
Output
Table 4-1 MRLDS-250 Behavior During Alarm Conditions
NOTE: The alarm feature includes a 20% dead
band to prevent alarm "chatter" if the
concentration hovers near the alarm setpoint.
Once the alarm has been triggered, it will
remain latched until the concentration drops below
80% of the alarm setpoint.

4.5. Gas Detector Faults

4.5.1. Overview

There are two levels of fault monitoring built into
the gas detector:
1. Non-critical
2. Critical
026-1315 Rev 2 11-APR-2017