PureAire Monitoring Systems BC TX-FM User manual

Model TX-FM/FN
Sensor Head
Instruction Manual
PureAire Monitoring Systems, Inc.
1140 Ensell Road
Lake Zurich, Illinois 60047
Phone: [phone]
Fax: [phone]
Toll-Free: 888-788-8050
Pureairemonitoring.com
Rev 1.0 August 2023

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Welcome to PureAire Monitoring Systems
I’d like to thank you for investing in our continuous life safety and process control toxic gas
monitoring systems.
PureAire offers an unbeatable combination of experience and innovation in solving the safety
and environmental needs of our customers. We’re capable of providing small systems of a few
points to a total multi-point turnkey computerized package.
PureAire’s proprietary sensor cell technology and state-of-the-art electronics are designed to
interface with the latest distributive or PLC based control systems. We believe that our experience,
innovative products and commitment to service will satisfy your specific monitoring needs now and
in the future.
Our growth is a result of our total commitment to supporting our customers. We’re available 24
hours a day, 7 days a week to help you when you need us. Our 24 hour Emergency phone number
is 1-847-541-1968. We can provide field service, preventative maintenance programs and training
to your technicians in the operation of our equipment. Our goal is to provide the best after sale
service and support in the industry. That’s just one way PureAire takes that extra step to ensure
your complete satisfaction.
Thank you again for investing in PureAire Monitoring Systems for your monitoring needs and
I’m proud to welcome you to our family of valued and satisfied customers.
Sincerely,
Albert A. Carrino
President

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Table of Contents
1: Introduction........................................................................................... 3
1.1 Component Identification............................................................. 3
1.2 Component Identification TX-1100FK ........................................ 4
2: Specifications........................................................................................ 6
2.1 Performance Specifications.......................................................... 6
2.2 Gas Detection System .................................................................. 6
2.3 Signal Outputs .............................................................................. 6
2.4 Electrical Requirements ............................................................... 6
2.5 Physical Characteristics................................................................ 7
3: Installation ............................................................................................ 8
3.1 Site Requirements ........................................................................ 8
3.2 Mounting ...................................................................................... 8
3.3 Sensor Installation ........................................................................ 8
3.4 Wiring......................................................................................... 10
3.5 Initial Startup.............................................................................. 11
4: Normal Operation ............................................................................... 12
4.1 Concentration Display and Indicator Lights............................... 12
4.2 Routine Maintenance Schedule.................................................. 12
4.3 Loss of Power Indicator ............................................................. 13
5: Maintenance & Calibration................................................................. 14
5.1 Sensor Cell Removal and Installation ........................................ 14
5.2 Electrolyte Replacement............................................................. 16
5.3 Sensor Calibration ...................................................................... 21
6: Diagrams and Schematics
6.1 TX-FMD Dimensional Schematic.............................................. 25
6.2 TX-FM Dimensional Schematic ................................................ 26
6.3 TX-FN Dimensional Schematic ................................................. 27
7: Appendix ............................................................................................ 28

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1: Introduction
TX-FM/FN series sensor heads are self-contained gas detection systems suitable
for a wide range hazardous gases, including ammonia, chlorine, HCl, and
hydrogen. Each system consists of an amperometric, electrochemical sensor cell
and two-wire transmitter. TX-FM/FN series sensor heads may be used as stand-
alone gas detectors or linked to an optional controller (RX-1G) or your own
centralized control and surveillance system.
The transmitter is available either with a local display (FM series) or without a
local display (FN series).
1.1 Component Identification
1.1.1 Overall System Composition
The TX-FM/FN may be integrated into the overall hazardous gas monitoring
system as shown in the following drawing. It may also be used as a stand-alone
detection system.
1.1.2 Front View
VR1
VR4
VR2
VR3
CN3
CN1
CN2
J1
VR5
SPAN
ZERO
max.
min.
123
4
5
6
7
89
10
11
12
13
1 2 3
1 2 3 4
1. 4-20 mA Signal Output Terminal — This connection serves as both the
4-20 mA output connection and 24 VDC power input connection. See section
3: Installation for more information.
2. Calibration Jack — This port is used when calibrating non-display units.
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3. Sensor Cable Terminal Block — This terminal is used to connect the
sensor cable.
4. Span Potentiometer — This potentiometer is used to adjust the sensitivity
of the sensor cell. It should only be adjusted when calibrating the instrument.
5. Zero Potentiometer — This potentiometer is used to adjust the instrument’s
4 mA analog output signal to ensure that it is transmitting a 4 mA signal
when the instrument is reading a zero concentration. On FM units, this pot is
located on the front panel; on FN units, it is located on the left hand
connector.
6. Sensor Holder — Serves as a mounting bracket for the sensor.
7. Sensor Fastening Screw — Holds sensor to the sensor holder.
8. Sensor Cover — This cover protects the gas sensor. It threads onto the
sensor holder.
9. Gas Sensor — An amperometric, electrochemical sensor which detects and
measures the target gas. Different gas sensors are required to detect different
gases. When exposed to the target gas, the sensor outputs an electrical signal
proportional to the gas concentration.
10. Cable Port — This is the opening in the transmitter housing for connecting
the 4-20 mA output and 24 VDC power cable.
11. Transmitter Cover — A removable, waterproof cover that protects the
interior of the transmitter.
12. Mounting Holes — Mounting brackets/holes are provided on both sides of
the transmitter housing as well as within the housing itself to permit
convenient wall mounting.
13. Transmitter Cover Fasteners — These captive screws secure the
transmitter cover in place.
1.2 Component Identification TX-1100FK O2
1.2.1 Overall System Composition
The TX-1100FK may be integrated into the overall hazardous gas monitoring
system as shown in the following drawing. It may also be used as a stand-alone
detection system.

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1.2.2 Front View
1. Sensor Cover — This cover protects the gas sensor. It fastens directly to the
transmitter Nema 4X enclosure.
2. Gas Sensor — An amperometric, electrochemical sensor which detects and
measures the target gas. Different gas sensors are required to detect different
gases. When exposed to the target gas, the sensor outputs an electrical signal
proportional to the gas concentration.
3. Cable Port — This is the opening in the transmitter housing for connecting
the 4-20 mA output and 24 VDC power cable.
4. Transmitter Cover — A removable, waterproof cover that protects the
interior of the transmitter.
5. Transmitter Cover Fasteners — These captive screws secure the
transmitter cover in place.
6. Panel Knob — Pull to unlock and open the front panel. This provides
access to the power terminal Phoenix connector.
1 & 2
3
4
5
6

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2: Specifications
NOTE: Due to our commitment to continual product improvement, all
specifications are subject to change without notice.
2.1 Performance Specifications
Models: TX-FM — Single point, with local analog display.
TX-FMD — Single point, with local digital display.
TX-FHD — Single point, with local digital display and remote sensor cell
TX-FN — Single point, without local analog display.
TX-1100FK — Single point, with local analog display
Sensor Type: Diffusion type electrochemical cell (2 or 3 wire);
plug-in sensors and sensors configured for remote installation also available.
TX-1100FK – zirconium oxide sensor cell
Response Time: Within 30 seconds to T90.
Repeatability: ±10% of full scale.
Fault Indicators: Loss of VDC power (4 mA signal drops to 0).
Operating Temperature: 14° to 113°F (-10° to +45°C); consult PureAire for lower operating temperatures.
Humidity: Sensor dependent; typically 20 to 95% RH; consult PureAire for sensors which
can operate in 100% condensing RH environments.
2.2 Gas Detection System
Type: Proprietary electrochemical gas sensor; renewable.
Disposable sensors also available.
Sensor Life: 4 to 5 years under normal conditions;
1-2 years for disposable sensors.
Detectable Gases: Consult PureAire.
2.3 Signal Outputs
Local Display: TX-FM — Analog meter calibrated for the specific target gas.
TX-FMD — Digital display calibrated for the specific target gas.
TX-FHD — Digital display calibrated for the specific target gas.
TX-FN — No local readout.
TX-1100FK — Analog meter calibrated for oxygen
Analog Output: DC 4-20 mA (2-wire system).
TX-1100-FK DC 4-20mA (3-wire system)
2.4 Electrical Requirements
Power: 24 VDC external power.
Consumption: Approximately 1.0 watt
TX-1100FK - 500mA current
NOTE: The TX-1100FK O2 monitor requires a 5-minute warm-up.

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2.5 Physical Characteristics
Dimensions: 4.9 (W) x 6 (H) x 2.54 (D) inches;
125 x 177 x 75 mm
Weight: 1.1 pounds (0.5 kg)
Enclosure Type: General purpose IP 65 NEMA 4X; not intended for explosive atmospheres.
Optional intrinsic safety barrier available for installation in Class I, Division 1,
Group B,C, and D hazardous areas.
Installation Options: Low temperature sensor enclosure.
Bulkhead fittings for remote sensor installation.

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3: Installation
3.1 Site Requirements
The TX-FM/FN/FK Sensor Head should be mounted in an area free of vibration
and electrical noise or interference. If possible, avoid areas with high
temperatures or relative humidity.
The unit should be installed in a location where gas leaks are likely to occur or
where released gases may accumulate. Air flow within the monitored area, the
characteristics of the target gas (lighter or heavier than air), and the position of
work stations and personnel should all be considered in determining the most
suitable installation location.
Allow sufficient space around the instrument to permit access for maintenance
and calibration.
WARNING: The TX-FM/FN is not designed for installation in hazardous areas.
Consult PureAire for information on enclosures for use in hazardous
environments.
3.2 Mounting
IMPORTANT: The TX-FM/FM must be mounted with the sensor pointed
directly down. Do not install with the sensor at greater than a 45° angle from
vertical. Do not install the sensor cell horizontal.
The TX-FM/FN is designed primarily for wall mounting and should be installed
no closer than 8.85 inches (260 mm) above floor level.
See Section 6 for mounting schematics.
3.3 Sensor Installation
NOTE: The following applies to type “D” diffusion sensors only. Consult
PureAire for installation information on plug-in type sensors.
IMPORTANT: Be careful not to turn the sensor or touch the membrane on the
bottom of the sensor during installation.
1. Remove the transmitter cover. It is held in place by captive screws mounted
in each of its four corners.
2. Remove the sensor cover by rotating it counterclockwise (right to left).
3. Insert the sensor cable through the sensor holder and into the transmitter
housing.
4. Carefully push the top of the sensor into the sensor holder and fasten it in
place by gently turning the fastening screw. Do not overtighten!
5. Replace the sensor cover.
6. Connect the sensor cable to the sensor cable terminal block. Depending on
the gas being monitored, the sensor cable will have either three or four wires.
IMPORTANT: Remove the shorting wire or current generator from the black
and white sensor cell wires before connecting the sensor cell to the transmitter.