1�1 Product Description; 1�1�1 The Xnx ® Universal Transmitter - Honeywell XNX Technical Manual

XNX Universal Transmitter
1.1 Product Description
1.1.1 The XNX Universal Transmitter
®
The XNX Universal Transmitter is a comprehensive gas detection
system designed to operate in hazardous locations
multiple sensor technologies, catalytic bead, electrochemical
(EC), or infrared (IR) to detect toxic gases, flammable gases, and
oxygen depletion gas hazards� Each technology has a dedicated
personality board�
Catalytic bead technology is used with the XNX mV personality
board� Catalytic bead sensors respond to a wide variety of
combustibles so are typically used for flammable gas detection�
Electrochemical technology is used with the XNX
electrochemical board� EC sensors measure toxic gases in
low concentrations� The XNX EC sensors employ the patented
Reflex™ cell fault diagnosis routine� Reflex™ checks for cell
presence, cell dry-out, and cell open or short circuit� Reflex™ is
automatically initiated by the transmitter at eight-hour intervals�
It is also initiated on power up or sensor exchange� In the
event of a cell failing this test, a sensor fault code is displayed�
Reflex™ diagnostics occur in the first minutes of the power up
sequence�
Infrared technology is used with the XNX IR board� IR sensors
optically absorb gases that fall into the infrared spectrum�
For additional information about any of the three sensor types,
refer to the applicable data sheet for the supported sensor in
Figure 1�
The XNX Universal Transmitter also allows for an optional
There are three main types of gas hazards: flammable, toxic, and asphyxiant� A flam-
1
mable gas hazard is one in which there is a risk of fire and/or explosion (e�g�, a situation
in which a gas such as methane, butane, or propane is present)� A toxic gas hazard is
one in which there is a risk of poisoning (e�g�, a gas such as carbon monoxide, hydrogen
sulfide, or chlorine is present)� An asphyxiant hazard would include a risk of suffocation
through oxygen deficiency� (Oxygen can be consumed or displaced by another gas�)
Section 1 - Introduction
communication board� There are three types of boards:
relay, Modbus
Communications for additional information�
and utilize
1
XNX Universal Transmitter
Personality Personality
IR
mV
XNX EC
�
Figure 1. XNX Universal Transmitter and supported sensing technologies
The XNX Universal Transmitter relies on 4-20mA output, refreshed
at least every two seconds (once per second is typical), in which
the output is proportional to the gas concentration�
10
, or Foundation Fieldbus� See Section 1�1� 2
® TM
Searchpoint Optima Plus
CL H NH O
2 2 3 2
ClO H S NO PH
2 2 3
Sensepoint HT
NO SO
CO HF
2 2
Sensor Type Sensor Type y T T
Point and Open-Path Infrared Searchpoint Optima Plus, Searchline Excel
705, 705HT, Sensepoint, Sensepoint HT, MPD
Flammable and Toxic
(Catalytic Bead Flammable, IR Flammable and IR CO
Electrochemical sensors, with Hot Swap, pre-calibrated
Toxic and O Sensing
through Intrinsically Safe (IS) barrier
2
Searchline Excel
705
705HT
Multi-Purpose
Detector (MPD)
Catalytic Bead
Sensepoint
Infrared Flammable
Infrared Methane/CO
Supported Sensors Supported Sensors
2
)
2