Emerson MRLDS-450 User manual

MRLDS-450
IP41 & IP66 Refrigerant Gas Detection

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1. INTRODUCTION
The MRLDS-450 refrigerant gas detector is designed for use in refrigeration applications, it may be used as a
stand-alone device or connected to a facility’s building management system (BMS). It enables compliance with
refrigerant safety codes (ASHRAE 15 and EN378) and features audible and visual alarms to alert personnel
in the event of a refrigerant leak.
The complete MRLDS-450 manual is available to download scanning the QR code at the end of this Quick
Refence Guide, or at the address: https://webapps.emerson.com/Dixell/Pages/Manuals
1.1 Safety Instructions
IMPORTANT: Before using this product, carefully read and strictly follow the instructions in
the manual. Ensure that all product documentation is retained and available to anyone
operating the instrument.
DANGER: This instrument is neither certified nor approved for operation in oxygen-
enriched atmospheres. Failure to comply may result in personal injury or death.
WARNING: Use this product only for the purposes specified in this document and under
the conditions listed.
WARNING: This instrument has not been designed to be intrinsically safe for use in areas
classified as being hazardous locations. For your safety, DO NOT use it in hazardous
(classified) locations.
WARNING: In the event of an alarm or over-range condition, the sensor must be
recalibrated to ensure continued accuracy.
WARNING: This product must be recalibrated if installed in a non-room condition
environment (i.e. temperature or humidity extremes).
WARNING: The gas diffusion path can become occluded (moisture, dust, debris, frozen
condensation) over time resulting in reduced or complete lack of gas detection and
alarming function. Routine visual inspection of the gas detector and bump testing are
suggested to ensure proper gas detection and alarm function.
CAUTION: Except for maintenance detailed in this manual, these products should only be
opened and / or serviced by authorized technical personnel. Failure to comply may void
the warrant.
CAUTION: Operator assumes responsibility for complying with all laws, rules and regulations
governing the use of this product.
CAUTION: Use only genuine parts and accessories. Failure to comply may impair the
operation of the product and / or void the warranty.
CAUTION: Only operate the product within the framework of a risk-based alarm signaling
concept.

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2. PRODUCT DESCRIPTION
2.1 Intended Uses / Applications
MRLDS-400 gas detectors are to be installed in non-classified, non-hazardous, permanent locations for the
purpose of continuously monitoring ambient air (indoor or outdoor) for the following gas types:
•Refrigerants
•Oxygen
•Toxic and combustible gases
WARNING: This instrument is neither certified nor approved for operation in oxygen-
enriched atmospheres. Failure to comply may result in EXPLOSION.
WARNING: This instrument has not been designed to be intrinsically safe for use in areas
classified as being hazardous locations. For your safety, DO NOT use it in hazardous
(classified) locations.
WARNING: It is possible to identify this instrument as a safety device only evaluating the
final application and location, which defines the relevant local laws, applicable standards
and required technical characteristics; therefore, the evaluation of the MRLDS-450 as a
safety device will be ultimately assessed by the customer / installer.
2.2 Transmitter Construction
MRLDS-400 gas detectors may be purchased in the following configurations:
Enclosure
IP41
IP66
Relays
3
3
Communication
Modbus
Modbus
Output
Analog
Analog
Sensor
Integrated
Integrated

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2.3 Technical Specifications
Category
Specifications
Signals to Central
Controller
Analog Current
Normal operation:............................................. 4 to 20 mA
Drift below zero:..................................................... 3.8 mA
Measuring range exceeded:................................. 20.5 mA
Instrument fault:.................................................. ≤ 1.2 mA
Fault on analog interface:.................................... > 21 mA
Offline mode/Maintenance signal:....... 3 mA steady signal
Signals to Central
Controller
Analog Voltage
0 to 5V; 1 to 5V; 0 to 10V; 2 to 10V (selectable). During
fault condition, 1 to 5V and 2 to 10V outputs are 0V.
Modbus RTU over
RS-485
Baud rate:............................. 9,600 or 19,200 (selectable)
Start bits:......................................................................... 1
Data bits:......................................................................... 8
Parity:.................................. None, odd, even (selectable)
Stop bits:............................................... 1 or 2 (selectable)
Retry time:.................... 500 ms, min time between retries
End of message:............................... Silent 3.5 characters
Power Supply and
Relays
Operating Voltage
19.5 to 28.5 VDC; 24 VAC ± 20%, 50/60 Hz
Inrush Current
1.5 A
Operating Current,
Max.
4W, 170mA @ 24VDC
Relay Rating
3 SPDT
1A at 30 VAC/VDC, resistive load
Audible Alarm
Internal Buzzer ≥72 dB at 4” (10 cm)
Alarm Delay
0 to 15 minutes (selectable)
Wiring
Power and Analog
Signal
2-core shielded cable, 16 to 20 AWG (0.5 to 1.5 mm2)
Modbus Network
3-core, 2 twisted pair + ground, shielded cable with 120 Ω
characteristic impedance, 16 to 24 AWG (0.2 to 1.5mm2)
Cable Gland
M20, 10-14mm cable outer diameter
M16, 4-8mm cable outer diameter

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Physical
Specifications
Enclosure
Protection
IP41 / IP66
Enclosure Size
(W×H×D) (Approx.)
MRLDS-450 IP41: 6.5× 6.5×3.0” (165×165×77 mm)
MRLDS-450 IP66: 6.5×6.5×3.4” (165×165×87 mm)
Weight (Approx.)
1lb, 1oz (480 g)
Environmental
Temperature
- 40 to 120 ºF (-40 to 50 ºC)
Storage
Temperature
- 5 to 100 ºF (-20 to 40 ºC)
Humidity
5 to 90 %RH, non-condensing
(15 to 90 %RH, non-condensing, EC sensors excl. O2)
Sensors
See paragraph Sensor Specifications for detailed
information.
Influences
For influences on the measurement performance and
restrictions of a particular sensor see sensor data sheet.
Agency Approvals
CE, EN 50270:2015, UL/CSA/IEC/EN 61010-1
2.4 Components
CAUTION: This product uses semiconductors which can be damaged by electrostatic
discharge (ESD). When handling the printed circuit boards (PCBs), observe proper ESD
precautions so that the electronics are not damaged.
2.4.1 MRLDS-450 Components
#
Component Description
1
M16 Cable Glands (x6)
2
Rubber Gasket
3
Internal Alarm Buzzer
4
Power Connections (x2)
5
Digital Connection (Modbus)
6
Analog Connection
7
Tactile Switch #1
8
Ribbon Cable Connection (To Sensor)
9
Tactile Switch #2
10
Relay 3 Connection (FAULT)
11
Relay 2 Connection (HIGH)
12
Relay 1 Connection (LOW)
13
Magnetic (Mag) Switch #1
14
Magnetic (Mag) Switch #2
15
M20 Cable Glands (x2)
Table 1 - Component Descriptions
Figure 2 - Component Locations

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3. INSTALLATION
IMPORTANT: The manufacturer of this product requires that a bump test or calibration be
performed following installation to verify instrument functionality.
3.1 Mechanical Installation
WARNING: DO NOT allow the lid / sensor to hang from the ribbon cable. Failure to comply
may result in damage to the product.
1. Using the provided hardware, securely mount the MRLDS-400 gas detector according to the product
dimensions, maximum wiring lengths and following considerations:
a. Environment: the full range of environmental conditions when selecting a location.
b. Application: the specifics of the application (possible leaks, air movement / draft, etc.) when
selecting a location.
c. Accessibility: the degree of accessibility required for maintenance purposes when selecting a
location.
d. Target Gas: the specific gravity of the target gas when selecting the height of the instrument.
2. Using a 5/32″ (4 mm) hex key / allen wrench (not included) remove the lid and disconnect the ribbon
cable from the base.
3. Set the lid and rubber gasket (IP66-rated enclosures only) aside to be reinstalled later.
3.2 Electrical Installation
3.2.1 Safe Connection of Electrical Devices
WARNING: Before connecting this instrument to electrical devices, consult the
manufacturer or a qualified professional. Failure to comply may result in injury and / or
damage to the product.
3.2.2 Preparations
IMPORTANT: Analog output is configured for 4 to 20 mA output by default. The MRLDS-
450 have a jumper on the analog connection. This jumper MUST be removed to use the
analog 4 to 20mA output signal. If the jumper is removed AND the 4 to 20mA signal is not
used, the unit will go into fault. The analog output is designed as sourcing.
CAUTION: Ensure wiring for relays and connections for sensor(s) are made before
applying power.
CAUTION: This product uses semiconductors which can be damaged by electrostatic
discharge (ESD). When handling the printed circuit boards (PCBs), observe proper ESD
precautions so that the electronics are not damaged.

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3.2.3 Power & Signal Wiring
1. Locate the relevant connections (Power, Analog, Modbus) and remove the terminal block from the
PCBA. (The PCB terminal blocks are pluggable type and may be removed to aid termination).
2. Remove plugs from the corresponding M16 cable glands.
•The product comes with cable glands and plugs pre-installed. (The power entry cable gland
is shipped from the factory without a plug.)
3. Using the appropriate cable glands, insert wires into the enclosure.
4. Secure the wires in each terminal block and, pressing firmly, reinstall the terminal block into the PCBA.
•Polarity must not be reversed.
•For 24 VAC installations in a daisy-chain configuration, the neutral polarity must be maintained
for all instruments.
5. Remove all excess cable from the housing before securing the cable glands.
3.2.4 Relay Wiring
WARNING: Relays are rated for 0 to 30V AC/DC. DO NOT apply mains power onto these
relays.
1. Locate the relevant connections (Relay 1, Relay 2, Relay 3) and remove the terminal block from the
PCBA.
2. Remove plugs from the corresponding M16 cable glands.
3. Using the appropriate cable glands, insert wires into the enclosure.
4. Secure the wires in each terminal block and, pressing firmly, reinstall the terminal block into the PCBA.
5. Remove all excess cable from the housing before securing the cable glands.
3.3 Reinstall Sensor and Connect Lid
CAUTION: DO NOT leave excess cable inside of the gas detector housing. Failure to
comply may result in damage to the product.
CAUTION: To achieve proper seal in the IP66 enclosure, the lid screws should be torqued
to 15 to 20 lbf in (1.5 to 2.0 Nm).
1. Reinstall the rubber gasket. Ensure that it is correctly seated by placing the side with two grooves
face down and the edge with two bumps on the top.
Figure 4 - Rubber Gasket Placement

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2. Reconnect the ribbon cable from the sensor to the PCBA as shown:
3. Ensure no cables are interfering with the sensor module and close the lid.
4. Using a 5/32” (4 mm) hex key/allen wrench, tighten the lid screws in an X tightening pattern:
Figure 5 - Tightening Pattern
4. OPERATION
4.1 Status Indication
The MRLDS-400 gas detectors provide external indication of their current operational state via audible and
visual feedback. (MRLDS-450 gas detectors also provide relays outputs.) Visual indication of the instrument
status is provided by a single tri-color LED (Green / Red / Orange) as indicated below:
State
LED
Buzzer
Relay 1
(LOW)
Relay 2
(HIGH)
Relay 3
(Fault)
Warm-up
OFF
OFF
OFF
Normal
OFF
OFF
OFF
Low Alarm
ON
OFF
OFF
High Alarm
ON
ON
OFF
Offline
OFF
OFF
OFF
Fault
OFF
OFF
ON
Negative Gas Fault
OFF
OFF
ON
Zero Cal. Fault
OFF
OFF
OFF
Span Cal. Fault
OFF
OFF
OFF

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4.2 Switch Functions
User interaction with the MRLDS-400 gas detector is accomplished through the use of two magnetic switches
located on the bottom of each unit. To actuate a magnetic switch (referred to as MAG#1 or MAG#2), apply the
supplied magnetic wand to the relevant switch location as indicated below:
Depending on the duration the switch is held, a short “TAP” or long “HOLD” will be detected:
•To carry out a tap function, tap the relevant switch location for 1 second, until a single “chirp” is heard,
remove wand to confirm a “TAP.”
•To carry out a hold function, do not remove the magnetic wand after the first chirp but continue to hold
for >5 seconds, until a double “chirp” is heard, remove wand to confirm a “HOLD.”
•If either switch is held for >30s, a stuck switch fault will be indicated.
To interact with the instrument without use of the magnetic wand, two internal push button tactile switches may
be used. Remove lid without removing ribbon cable to access. Internal switches TACT#1 and TACT#2 mirror
the functions of MAG#1 and MAG#2.
The function of each switch depends on the current state of the instrument as indicated in the following table:
State
Switch 1
(Tap)
Switch 1
(Hold)
Switch 2
(Tap)
Switch 2
(Hold)
Warm-up
Enable
Bluetooth®
Connectivity
-
Disable
Bluetooth®
Connectivity
-
Normal
Start Zero Calibration
Start Span Calibration
Low Alarm
Mute Buzzer
Ack. Latched Alarm
High Alarm
Mute Buzzer
Ack. Latched Alarm
Offline
-
-
Fault
Mute Buzzer
Ack. Latched Fault
Negative Gas Fault
Mute Buzzer
Start Zero Calibration
Zero Cal. Fault
Acknowledge Fault
-
Span Cal. Fault
-
Acknowledge Fault
4.3 Reset System to Factory Default Settings
To reset system to factory defaults, remove lid and hold TACT#1 and TACT#2 simultaneously for 30 seconds.
Instrument will restart to confirm factory reset. Alternatively, see Section 4.2.3.4 “Reset to Factory Defaults”,
for instructions on resetting instrument configuration via the MRLDS-400 App.

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4.4 MRLDS-400 Smartphone Application
To download the MRLDS-400 App, visit either the App Store or Google Play.
The companion smartphone application allows users to perform a variety of functions to configure and interact
with the MRLDS-400 gas detector, including:
●View real-time measurements
●Configure instrument
●Test outputs
●Calibrate / bump test instrument
●Generate customizable calibration certificates
4.4.1 Enable Bluetooth® Connection
1. Enable Bluetooth®discovery by tapping MAG#1 for 1-second. (After 10-seconds, device will indicate
that it is discoverable with audible heartbeat until it has been paired, discovery has timed-out or has
been cancelled.)
2. Launch the MRLDS-400 App and click the Bluetooth®icon at the bottom of the screen to initiate a
scan.
3. Select the instrument from the list of available gas detectors.
•MRLDS-450 default alias is “18TMAE”
4. When prompted, enter the passkey (default is “123456”).
WARNING: Default alias, passkey and unlock code can be changed via the MRLDS-400
App’s configuration menu. Default values should be changed after instrument installation for
security purposes.
4.4.2 Checking Status
Current instrument status can be viewed from the Home tab, including the following:
The color code of the Status Ring is shown in the next page.
#
Description
1
Alias - user configured instrument name
2
Serial Number - instrument 8 digit serial number
3
Gas - gas type currently detected by instrument
4
Status Ring - provides visual indication of various
instrument states (expanded on below)
5
Live Measurement - current measurement in given
measurement units
6
Measurement Unit - displayed measurement unit
(PPM / PPB / %LEL / %VOL)

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State
Status Ring
Description
Warm-up
Green
Gas detector stabilizing after power on or restart
Normal
Green
Normal operation
Low Alarm
Yellow
Gas measurement has exceeded low alarm setpoint
High Alarm
Red
Gas measurement has exceeded high alarm setpoint
Offline
Orange
Gas Detector in maintenance mode and is not actively
monitoring gas
Fault
Orange
A fault has been detected
Negative Gas
Fault
Orange
Gas detector calibration has drifted below zero, requires zero
calibration
Zero Cal. Fault
Orange
Error occurred during zero calibration. Zero calibration has not
be updated. Zero calibration required.
Span Cal. Fault
Orange
Error occurred during span calibration. Span calibration has
not be updated. Span calibration required.
4.4.3 Instrument Configuration
For security, access to configuration and calibration options are restricted to authorized users only. Access to
these functions require use of an unlock code. To unlock instrument configuration:
•Configure Tab When prompted, enter unlock code to access device configuration. (The
instrument’s default code is “1234”). Instrument will remain unlocked until Bluetooth®connection
has ended.
WARNING: Default alias, passkey and unlock code can be changed via the MRLDS-400
App’s configuration menu. Default values should be changed after instrument installation for
security purposes.

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