United Process Controls Oxyfire-LT User manual

Oxyfire-LT
Modular Oxygen Sensor
Installation / Operation Manual
© United Process Controls, Inc.

United Process Controls, Inc. Oxyfire-LT Installation/Operation Manual
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Revision 3 January 27, 2015
Copyright © United Process Controls, Inc.
No part of this document may be stored or reproduced by any means whatsoever without prior written
permission of United Process Controls, Inc.
All trademarks used in this publication are duly marked and the sole property of their respective owners. No
attempt at trademark or copyright infringement is intended or implied.
The MMI oxygen sensor is a zirconium type oxygen sensor to be used by the industrial operator at his or her own
risk. Oxyfire sensors are for use in combustion trim control only. Do not use with full-range air/fuel ratio control.
United Process Controls, Inc. makes no warranties expressed or implied beyond the written warranty presented at
initial purchase. United Process Controls, Inc. is not responsible for any product, process, damage or injury
incurred while using the oxygen sensor. United Process Controls, Inc. makes no representations or warranties
with respect to the contents hereof and specifically disclaims any warranties of merchantability or fitness for any
particular application or purpose.
For assistance please contact: United Process Controls Inc.
TEL: [phone] • FAX: [phone]
Toll-Free North America [phone]
[email protected]
www.group-upc.com

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Table of Contents
1INTRODUCTION ..........................................................................................................................5
1.1GENERAL................................................................................................................................. 5
1.2OVERVIEW .............................................................................................................................. 5
1.3THEORY OF OPERATION...................................................................................................... 5
1.4SYSTEM CONFIGURATION.................................................................................................. 6
1.5STANDARD SPECIFICATIONS ............................................................................................. 6
2INSTALLATION ...........................................................................................................................9
2.1APPLICATION CONFIRMATION.......................................................................................... 9
2.2ITEMS REQUIRED .................................................................................................................. 9
2.3SENSOR HOLE SIZE ............................................................................................................... 9
2.4INSTALLATION PORTS ......................................................................................................... 9
2.5WALL THICKNESS ............................................................................................................... 10
2.6COOL INSTALLATION (100 ° F or lower)........................................................................... 11
2.7HOT INSTALLATION ........................................................................................................... 11
2.8ELECTRICAL CONNECTIONS:........................................................................................... 11
3REFERENCE AIR........................................................................................................................12
3.1Clean, Dry Air Supply ............................................................................................................. 12
3.2Suitable Reference Air Units ................................................................................................... 12
4VERIFICATION...........................................................................................................................14
4.1Method #1 ................................................................................................................................ 14
4.2Method #2 ................................................................................................................................ 14
5OXYFIRE-LT REPLACEMENT COMPONENTS.....................................................................15
5.1REPLACMENT PRECAUTIONS .......................................................................................... 16
5.2ELECTROLYTE REPLACEMENT ....................................................................................... 17
6TROUBLESHOOTING................................................................................................................19
6.1ITEMS REQUIRED ................................................................................................................ 19
6.2SIGNAL TROUBLESHOOTING ........................................................................................... 19
6.3HEATER TROUBLESHOOTING.......................................................................................... 20
7APPENDIX...................................................................................................................................21
7.1OXYGEN CALCULATION ................................................................................................... 21
7.2STANDARD OXYFIRE SENSOR WIRING CONNECTIONS ............................................ 22
7.3OXYGEN/TEMPERATURE/ MILLIVOLT CHART ............................................................23
7.4USEFUL FORMULAS............................................................................................................ 24

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For the safe use of this equipment
CAUTION
Sensor Handling
The cell (sensor) at the tip of the detector is made of ceramic (zirconia element). Do not drop the detector or
subject it to pressure stress.
Do NOT allow the sensor (probe tip) to make contact with anything when installing the detector.
Avoid any direct water drop on the probe (sensor) of the detector when installing it.
Check the verification gas piping before introducing the gas to ensure there is no leakage of the gas. If
there is any leakage of the gas, the moisture drawn from the measuring gas can damage the sensor.
The detector (especially at the tip) becomes very hot. Be sure to handle it with gloves.
Oxyfire-LT may be heavy. Handle it with care. Do not drop it. Handle safely to avoid injury.
Sensor Heater
Only qualified personnel with knowledge of electrical equipment and safety procedures involving electrical
equipment should be allowed to work on this equipment. Connect the power supply for the heater only after
confirming that the supply power is switched off. Insure that heater voltage supply and current matches the
rating of this equipment.
Process Gas
Some process gases are dangerous to people. When removing this equipment from the protection tube and
mounting flange protect yourself from potential poisoning by using a protective mask or ventilating the area
well.

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1 INTRODUCTION
1.1 GENERAL
The Oxyfire-LT In-Situ Zirconia Oxygen Sensor has been designed to measure excess oxygen in a wide
variety of low temperature combustion processes. It is an outstanding unit for monitoring oxygen
concentrations in combustion gas of large or small boilers, industrial furnaces and combustion processes
or for the control of low percent oxygen combustion.
The analyzer consists of a detector and converter. Optional accessories, such as electronics, reference air
units, verification units, mounting assemblies, and protection tubes may be selected to enhance
installation. The complete installation provides system care, minimizes maintenance and provides
automated or manual verification. An optimal control system can be realized if the appropriate
supplemental equipment is selected.
The Oxyfire-LT utilizes high performace Oxyfire-LT Probe technology to provide cost-effective and
reliable oxygen sensing and control in low process tempeture applications.
1.2 OVERVIEW
The Oxyfire-LT is a self-heated device that is mounted into the process flue with a flange interface. The
probe is internally heated to operate at a temperature of 600º
º
C with the application 120V AC power.
Sensor is used to monitor and control the excess oxygen concentration in combustion gases of boilers,
incinerators and other industrial furnaces.
A low temperature sensor sampling gases from 500ºF (300ºC) up to 1100º
º
F (600º
º
C) is inserted into
the process gas stream via a flange, threaded adaptor, or sealable opening. The sensor may be
installed vertically or horizontally, depending on application specifics such as temperature, gas flow,
etc. The atmosphere around the sensor tip should be moving and not stagnant. For optimum results,
the sensor should be protected from direct flame contact and located at a point where combustion is
complete.
1.3 THEORY OF OPERATION
Yttria stabilized zirconia conducts oxygen ions at temperatures above 1000°F (540°C). The driving force
of the ion migration is the difference in the oxygen concentration between the process gas and the
supplied reference air. Partial pressure laws of gases state that oxygen molecules will travel from higher
to lower concentrations. Platinum electrodes, located on both the inside and the outside of the zirconia,
detect the voltage produced by the flow of these ions. This millivolt signal is a function of the difference
in oxygen concentration. Knowing the process temperature, reference gas oxygen concentration (20.9%)
and the millivolt signal, the Nernst equation is used to calculate the percent oxygen.
The Nernst Equation is as follows:
E 0.0215 mV
K






Tln
%O2_reference
%O2_process








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E = Sensor Output in Millivolts
T = Sensor Temperature in degrees Kelvin (degrees C + 273)
%O2_reference = Oxygen concentration on the inside of the zirconia substrate (20.9%)
%O2_process = Oxygen concentration on the outside of the zirconia substrate (unknown)
ln() = Natural log
1.4 SYSTEM CONFIGURATION
The basic system consists of a sensor, electronics and reference air unit.
1.5 STANDARD SPECIFICATIONS
Measurement Method Zirconium Oxide
Net O2Range PPM to 20.9%
Accuracy + 1.5% of observed process variable or 0.5% O2, whichever is greater
Response Time Less than 1 second for 98% of final value
Stability Less than 1% deviation in signal output over the life of the sensor
Operating Temp of Heater 1112ºF (600ºC)
Maximum Process Temp 1292°F (700°C)
Temp Limit Terminal Head 150ºF (65ºC) max.
Mounting Vertical or horizontal.
Construction
Inner Tube Zirconia
Outer Sheath Alumina, TSR
Terminal Head 6061-T6 aluminum
Heater Ceramic material (replaceable)
Integral Thermocouple Type “K”
Gas Calibration Not required. Verification of sensor possible.

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Insertion Rate 1 inch (25mm) per 5 minutes during a hot installation
Sensor Outputs Two millivolt output signals (electrolyte and type K thermocouple)
Interconnecting Cable Sensor to electronics
2-conductor twisted pair shielded Belden #6341PC cable
K T/C version: 1 cable, 2 conductor, solid extension grade wire
Warning
The oxygen sensor is heated to 600°C (1112°F) with 110VAC / 200VA mains power. The heater
power is a potential source of ignition and should only be energized in a non-explosive atmosphere or
when the atmosphere is safe from explosion. An interlock is provided in the sensor control system to
shut off the heater power when conditions are not safe. Never apply power to the heater in an explosive
atmosphere.
Oxyfire-LT Mechanical Information
Figure 1 Sensor Parts Identification
Figure 2 Heat Assembly

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Table 1 Standard Part Numbers
Part #: FO1 X -YYYY -Z
Sheath Style X
Alumina Open End 5
Alumina Closed
End 6
SS 316 Closed End 7
Insertion Length YYYY
in mm
12 304.8 1200
18 457.2 1800
24 609.6 2400
30 762 3000
36 914.4 3600
TC Type Z K

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2 INSTALLATION
2.1 APPLICATION CONFIRMATION
Call your local MMI Representative or MMI directly when planning your sensor installation. The
sensor location and depth of insertion are critical factors to consider and vary with different
applications. MMI Application Engineers are equipped to help with such information in many
applications.
2.2 ITEMS REQUIRED
To perform a sensor installation, you will need the following items:
Supplied with standard Oxyfire models:
1. K T/C models: 2-conductor solid extension wires
2. Polyvinyl coated copper wire, two conductor, stranded, 18 gauge, twisted pair,
shielded – Belden #6341PC
Ceramic fiber blanket insulation and/or refractory cement.
Sensor Reference Air: Clean, dry continuous air source – approximately 2 psi at 50 to
150cc/minute
Cooling Air: If the temperature of the sensor terminal head will exceed 300ºF (148ºC), air
should be blown across it to reduce the temp. The cooling air should be directed to flow
perpendicular across the sensor head.
2.3 SENSOR HOLE SIZE
The installation hole, through the refractory of the crown or wall, should be a minimum of 2 inches
(50mm) in diameter. The hole should always be straight, clean, and perpendicular to the wall or crown.
It is advised to always verify the hole size required for your application and sensor. MMI
Application Engineers can help with this matter.
2.4 INSTALLATION PORTS
The ports can be of different designs – open hole, threaded, and flanged. Applications with exterior
metal shells should use threaded or flanged type ports. Thread is 1.25” NPT size for standard Oxyfire
models. Applications with ceramic exterior shells may use the open hole, threaded, or flanged
connection ports. The flange or pipe will be cemented in to the refractory.

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2.5 WALL THICKNESS
Verify the exact thickness of the refractory in the crown or wall. A length of high temperature metal
wire, formed like an “L”, should be inserted into the refractory hole. Hook the lengths of wire against
the inside face of the refractory and mark the outside face of the furnace on the wire. Check the
dimension at several points around the circumference of the hole. This will indicate possible erosion or
build-up. Transfer this mark to the sensor sheath. Next mark 1 inch (25mm) increments along the length
of the sensor sheath starting at the tip.