RKI Instruments 65-2650RK-04 User manual

RKI Instruments, Inc.
www.rkiinstruments.com
65-2650RK-04
Molecular Property Spectrometer
M2A Transmitter
Operator’s Manual
Part Number: 71-0634
Revision: P1
Released: 3/23/23
TM

2• 65-2650RK-04 Molecular Property Spectrometer M2A Transmitter Operator’s Manual
WARNING
Read and understand this instruction manual before operating instrument.
Improper use of the gas monitor could result in bodily harm or death.
Periodic calibration and maintenance of the gas monitor is essential for proper
operation and correct readings. Please calibrate and maintain this instrument
regularly! Frequency of calibration depends upon the type of use you have and
the sensor types. For most applications, typical calibration frequencies are
between 3 and 6 months but can be more often or less often based on your
usage.

65-2650RK-04 Molecular Property Spectrometer M2A Transmitter Operator’s Manual • 3
Product Warranty
RKI Instruments, Inc. warrants gas alarm equipment sold by us to be free from defects in
materials, workmanship, and performance for a period of one year from date of shipment from
RKI Instruments, Inc. Any parts found defective within that period will be repaired or replaced, at
our option, free of charge. This warranty does not apply to those items which by their nature are
subject to deterioration or consumption in normal service, and which must be cleaned, repaired, or
replaced on a routine basis. Examples of such items are:
• Absorbent cartridges
• Pump diaphragms and valves
•Fuses
•Batteries
• Filter elements
Warranty is voided by abuse including mechanical damage, alteration, rough handling, or repair
procedures not in accordance with the operator’s manual. This warranty indicates the full extent
of our liability, and we are not responsible for removal or replacement costs, local repair costs,
transportation costs, or contingent expenses incurred without our prior approval.
THIS WARRANTY IS EXPRESSLY IN LIEU OF ANY AND ALL OTHER WARRANTIES AND
REPRESENTATIONS, EXPRESSED OR IMPLIED, AND ALL OTHER OBLIGATIONS OR
LIABILITIES ON THE PART OF RKI INSTRUMENTS, INC. INCLUDING BUT NOT LIMITED TO,
THE WARRANTY OF MERCHANTABILITY OR FITNESS FOR APARTICULAR PURPOSE. INNO
EVENT SHALL RKI INSTRUMENTS, INC. BE LIABLE FOR INDIRECT, INCIDENTAL, OR
CONSEQUENTIAL LOSS OR DAMAGE OF ANY KIND CONNECTED WITH THE USE OF ITS
PRODUCTS OR FAILURE OF ITS PRODUCTS TO FUNCTION OR OPERATE PROPERLY.
This warranty covers instruments and parts sold to users by authorized distributors, dealers, and
representatives as appointed by RKI Instruments, Inc.
We do not assume indemnification for any accident or damage caused by the operation of this gas
monitor, and our warranty is limited to the replacement of parts or our complete goods.

4• 65-2650RK-04 Molecular Property Spectrometer M2A Transmitter Operator’s Manual
Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
About the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 2: Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
External Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Internal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 3: Installation & Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Mounting the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Wiring the M2A Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 4: Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Information Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4 - 20 mA Signal Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Alarm Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Chapter 5: Configuration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Viewing & Changing M2A Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Chapter 6: Gas Type Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Selecting the Gas Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

65-2650RK-04 Molecular Property Spectrometer M2A Transmitter Operator’s Manual • 5
Chapter 7: Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Calibration Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Replacing Components of the M2A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Chapter 8: RS-485 Modbus Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Wiring the M2A in a Modbus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Using the M2A in a 4-wire Modbus System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Modbus Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Supported Modbus Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Chapter 9: Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Appendix A: Control Button Quick Reference Guide . . . . . . . . . . . . . . . . . . . . 58
Appendix B: PLC and DCS Device Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Appendix C: Function Code 16 Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

6• Chapter 1: Introduction 65-2650RK-04 Transmitter Operator’s Manual
Chapter 1: Introduction
Overview
This chapter briefly describes the 65-2650RK-04 M2A Transmitter. This chapter also describes
the 65-2650RK-04 Transmitter Operator’s Manual (this document). Table 1 at the end of this
chapter lists the specifications for the M2A.
About the M2A Transmitter
The M2A transmitter is a fixed mount, continuous-monitoring detector head. All user adjustable
parameters may be accessed using push button switches. In addition, calibration may be
performed non-intrusively by use of a magnetic wand accessory which activates magnetic
switches through a window at the front face of the detector head.
The M2A displays the current gas reading on an OLED display which is visible through the
window in the cover (front face) and provides a 4 - 20 mA signal which indicates the target gas
reading for use by a gas monitoring controller, recording device, or programmable controller. The
M2A also provides an RS-485 Modbus output. Three sets of relay contacts, two controlled by the
gas alarms and one by the fail alarm, rated at 115 VAC 5 amps are available for controlling
devices such as lights or horns or for controlling higher rated relays.
Four operating modes allow you to display and change setup and calibration settings and change
the gas type. They are Calibration Mode, Configuration Mode, Gas Type Mode, and Modbus
Mode.
About this Manual
The M2A Transmitter Operator’s Manual uses the following conventions for notes, cautions, and
warnings.
NOTE: Describes additional or critical information.
CAUTION: Describes potential damage to equipment.
WARNING: Describes potential danger that can result in injury or death.

65-2650RK-04 Transmitter Operator’s Manual Chapter 1: Introduction • 7
Specifications
Table 1 lists specifications for the M2A Transmitter. Table 2 and Table 3 lists detection ranges,
accuracy statements, and specifications for the MPS LEL combustible gas detector.
Table 1: M2A Transmitter Specifications
Alarm Settings
(Alarm 1/Alarm 2)*
• Combustible Gas (%LEL): 10% LEL / 50% LEL
Construction
(housing)
Explosion-proof Junction Box, NEMA 4X
Controls • Three push button switches
• Three magnetic switches for non-intrusive calibration
Input Power 10 - 30 VDC
Weight 4.5 lbs.
Signal Output
• 4 to 20 mA with impedance maximums listed below:
-12 VDC input: 500 ohms impedance max
-24 VDC input: 1000 ohms impedance max
• RS-485 Modbus
* These are RKI factory settings. See “Viewing & Changing M2A Parameters” on page 30 to change the
alarm settings.
** Independent of zero drift
Table 2: MPS LEL Detection Ranges and Accuracy
Target Gas Formula Detection Range Accuracy
at 50% LEL
Butane C4H10 0 - 100% LEL ± 5% LEL
Ethane C2H60 - 100% LEL ± 5% LEL
Hydrogen H20 - 100% LEL ± 5% LEL
Isobutane HC(CH3)30 - 100% LEL ± 5% LEL
Isobutylene C4H80 - 100% LEL ± 5% LEL
Isopropanol C3H8O 0 - 100% LEL ± 10% LEL
Methane CH40 - 100% LEL ± 3% LEL
Methyl Ethyl Ketone C4H8O 0 - 100% LEL ± 5% LEL
Octane C8H18 0 - 100% LEL ± 5% LEL
Pentane C5H12 0 - 100% LEL ± 5% LEL

8• Chapter 1: Introduction 65-2650RK-04 Transmitter Operator’s Manual
WARNING: When using the M2A, you must follow the instructions and warnings in this
manual to assure proper and safe operation of the M2A and to minimize the risk
of personal injury. Be sure to maintain and periodically calibrate the M2A as
described in this manual.
Applications
The MPS combustible detector is most effective in the following applications:
• High concentrations of hydrogen sulfide (H2S) or silicones present where sensor
poisoning is a common problem
• High-humidity environments where catalytic or IR sensors may not hold up
• Environments more likely to have mixtures of hydrocarbons present
Propane C3H80 - 100% LEL ± 6% LEL
Propylene C3H60 - 100% LEL ± 5% LEL
Toluene C7H80 - 100% LEL ± 12% LEL
Xylene C8H10 0 - 100% LEL ± 12% LEL
NOTE: The MPS sensor will respond to other combustible gases, but the accuracy has
only been determined for these 14 gases.
Table 3: MPS LEL Combustible Gas Detector Specifications
Sampling Method Diffusion
Area Classification Explosion-proof for Class I, Groups B, C, and D
Operating Temperature
Range
-20ºC to +50ºC (-4ºF to +122ºF)
Humidity Range 0 - 100% RH (non-condensing)
Pressure Range 80 - 120 kPa
Response Time T90 in 25 seconds
Dead Bands
•Methane(CH
4): 3% LEL
• All other gases: 5% LEL
NOTE: If the M2A’s or a connected controller’s dead band setting is
2% LEL for an MPS channel, a reading will not be displayed until it
has exceeded the MPS sensor's internal dead band.
Table 2: MPS LEL Detection Ranges and Accuracy
Target Gas Formula Detection Range Accuracy
at 50% LEL

65-2650RK-04 Transmitter Operator’s Manual Chapter 2: Description • 9
Chapter 2: Description
Overview
This chapter describes external and internal components of the M2A Transmitter. The transmitter
is a 4 - 20 mA type detector head. It consists of the MPS LEL detector, calibration adapter/splash
guard, terminal PCB, the M2A junction box, and the detector junction box. The two junction box
configuration is intended for situations where the detector needs to be installed at an inaccessible
location. The detector junction box can be installed at the inaccessible location and the M2A
junction box can be installed in a more readily accessible area.
External Description
This section describes the junction boxes and all external components of the M2A transmitter.
Figure 1: M2A External Components
Magnetic
Wand
Terminal
Strip
3/4 NPT Conduit Hub3/4 NPT Conduit
Hub, Plugged
Calibration Adapter/
Splash Guard
3/4 NPT
Conduit Hub
M2A
Junction
Box MPS LEL Detector
Detector
Junction Box
Mounting Slot (2x)
3/4 NPT
Conduit Hub
Window

10 • Chapter 2: Description 65-2650RK-04 Transmitter Operator’s Manual
Gas Detector
The MPS™ LEL detector is made up of the MPS combustible gas LEL detector housed and
encapsulated in a pipe nipple. The MPS sensor is immune to poisons, can be used in high
humidity, and does not require calibration as often as catalytic combustible sensors. It also
responds accurately to 14 different combustible gases.
A porous flame arrestor coated with a hydrophobic film that repels liquids is on one end of the
detector and allows sample gas to enter the detector. Four color coded leads, red, white, green, and
black, extend from the other end of the detector. Use the leads when connecting the detector to the
terminal block in the junction box.
M2A Junction Box
The M2A’s cast aluminum junction box protects the terminal PCB and wiring connections made
to the terminal PCB. Use the three 3/4 NPT conduit hubs to wire the remotely installed IR LEL
detector and connect wiring from an external device, typically an RKI controller. The top hub is
shipped with a factory installed and sealed conduit plug to avoid leaks into the junction box. If
necessary, the conduit plug can be removed and the top hub can be used for wiring.
WARNING: If the top conduit port is used for wiring, be sure to seal the threads to ensure
water does not enter the junction box. See “Wiring the M2A Transmitter” on
page 17 for complete wiring instructions.
Use the junction box’s two mounting holes to mount the M2A to a vertical surface at the
monitoring site. The window in the cover on the front of the junction box allows you to view the
OLED display and use the magnetic wand to actuate the magnetic control switches so you can
perform non-intrusive calibration. Removing the cover allows you to access the interior of the
junction box.
Detector Junction Box
The detector junction box is intended to be installed remotely from the M2A junction box. The
MPS LEL combustible gas detector is factory-installed in the bottom 3/4 NPT conduit hub. A
terminal strip is provided for wiring connections and the detector is factor- wired to one side of
this terminal strip. The other side of the terminal strip is for user-supplied wiring to the detector
terminal strip located in the M2A junction box. This wiring should go through the top 3/4 NPT
conduit hub. Three spacers installed on the back of the junction box controls the distance of the
junction box from a mounting surface.
Calibration Adapter/Splash Guard
A calibration adapter/splash guard is installed on the MPS LEL detector. A fitting at the bottom of
the calibration adapter/splash guard allows a length of tubing to be connected for calibration and
routed to a more easily accessible location (near the M2A junction box is optimal for ease of
calibration). The calibration adapter/splash guard also protects the detector from splashing water
or direct water spray.