Analytical Industries Inc (AII) GPR-3500 MO Operating Manual

Technical Specifications *

Accuracy:

Analysis:

Application: Intermittent monitoring of oxygen levels up to 100% O2

Area Classification: General purpose

Calibration:

Connections: 1/8" compression tube fittings

Controls:

Display:

Enclosure: Painted aluminum, 4 x 9 x 3", 8 lbs.

Flow Sensitivity: Not flow sensitive, 1-2 SCFH recommended

LED Indicators: LOW BATT (72 hr. warning); CHARGE mode

< 2% of FS range under constant conditions, e.g.
constant temperature, flow rate and ambient pressure

0-100% FS range

Max interval—3 months. Use certified span gas with 97­100% O2 (balance N2). To comply with FDA requirements
for medical grade O2, zero calibrate with not less than

99.9% N2 (balance O2) or span calibrate with not less
than 99.99% O2 (balance N2). For Oxygen 93
(transfilling), calibrate with 93% +0.1% O2 (balance N2).

Water resistant keypad; menu driven range selection,
calibration and system functions

Graphical LCD 2.75” x 1.375”; resolution 0.1%;
displays real time ambient temperature and pressure

GPR-3500 MO

Portable Oxygen Purity

Linearity: ±1% of full scale

Pressure:

Power: Rechargeable battery, 60 day cycle

Response Time: 90% of final reading in 13 seconds

Sample System: Flow indicator & control valve

Sensitivity: < 0.5% of FS range

Sensor Model:

Sensor Life:

Signal Output: 0-1V FS

Operating Range: 5ºC to 45ºC

Warranty: 12 months analyzer; 12 months sensor

Wetted Parts: Stainless steel

Optional Equipment

Sample conditioning system - Contact factory.

Inlet - regulate to 5-30 psig to deliver 1-2 SCFH flow;
vent - atmospheric

GPR-11-120-RTS

24 months in 100% O2 at 25ºC and 1 atm

Analyzer

Advanced Galvanic Sensor Technology

Proprietary Long Life Sensor

24 Months @ 100% Oxygen

Sensitivity 0.5% Full Scale
Rechargeable Battery Power
Barometric Pressure Compensated
Unaffected by Vibration & Motion
Designed for Industrial Use

ISO 9001:2008 Certified

INTERTEK Certificate No. 485

* Subject to change without notice

2855 Metropolitan Place, Pomona, CA 91767 USA ♦ Tel: [phone], Fax: [phone], www.aii1.com, e-mail: [e-mail] Rev 10/15

Advanced Instruments Inc.

GPR-3500 MO

Portable Oxygen Purity Analyzer

Owner’s Manual

Owner’s Manual

2855 Metropolitan Place, Pomona, CA 91767 USA Tel: [phone], Fax: [phone], e-mail: [e-mail], www.aii1.com

Table of Contents

Introduction
Quality Control Certification
General Safety & Installation
Features & Specifications
Operation
Maintenance
Spare Parts
Troubleshooting
Warranty
Material Safety Data Sheets
Correlate LCD to Signal Output Appendix

Advanced Instruments Inc.

1
2
3
4
5
6

7
8
9

10

B

1 Introduction

Your new oxygen portable oxygen purity analyzer incorporates an advanced electrochemical sensor specific to oxygen along with state­of-the-art digital electronics designed to give you years of reliable precise oxygen measurements in variety of industrial oxygen
applications.

To obtain maximum performance from your new oxygen portable oxygen purity analyzer, please read and follow the guidelines
provided in this Owner’s Manual.

Every effort has been made to select the most reliable state of the art materials and components, to design the portable oxygen purity
analyzer for superior performance and minimal cost of ownership. This portable oxygen purity analyzer was tested thoroughly by the
manufacturer prior to shipment for best performance.

However, modern electronic devices do require service from time to time. The warranty included herein plus a staff of trained
professional technicians to quickly service your portable oxygen purity analyzer is your assurance that we stand behind every portable
oxygen purity analyzer sold.

The serial number of this portable oxygen purity analyzer may be found on the inside the portable oxygen purity analyzer. You should
note the serial number in the space provided and retains this Owner’s Manual as a permanent record of your purchase, for future
reference and for warranty considerations.

Serial Number: _______________________

2

Advanced Instruments Inc.

Advanced Instruments Inc. appreciates your business and pledges to make every effort to maintain the highest possible quality
standards with respect to product design, manufacturing and service.

2 Quality Control Certification

Date: Customer: Order No.: Pass
Model:

Sensor:
Accessories:

Configuration:

Test:

Final:

Options:
Notes:

GPR-3500MO Oxygen Purity Transmitter S/N ___________________
GPR-11-120-4 Oxygen Sensor S/N ___________________

Owner’s Manual
A-2221 Sensor Flow Housing 1/8” FNPT (integral)

A-1151-B3 PCB Assembly Software Ver. _________
Range(s): 0-100%
NEMA 4 rated wall mount enclosure

Default zero (without sensor)
Default span @ 20uA
No interruption in operation when connecting AC charger/adapter
Calibrates at 20.9% oxygen in ambient air and 100% oxygen with adequate span
Analog signal output 0-1V (0-100% oxygen)
Baseline drift on zero gas < ± 2% FS over 24 hour period
Noise level < ± 1.0% FS
Span adjustment within 10-50% FS
Overall inspection for physical defects

3

Advanced Instruments Inc.

3 General Safety & Installation

Safety

This section summarizes the basic precautions applicable to all analyzers. Additional precautions specific to individual analyzer are
contained in the following sections of this manual. To operate the analyzer safely and obtain maximum performance follow the basic
guidelines outlined in this Owner’s Manual.

Caution: This symbol is used throughout the Owner’s Manual to Caution and alert the user to recommended safety and/or operating
guidelines.

Danger: This symbol is used throughout the Owner’s Manual to identify sources of immediate Danger such as the presence of
hazardous voltages.

Read Instructions: Before operating the analyzer read the instructions.
Retain Instructions: The safety precautions and operating instructions found in the Owner’s Manual should be retained for future

reference.
Heed Warnings Follow Instructions: Follow all warnings on the analyzer, accessories (if any) and in this Owner’s Manual. Observe

all precautions and operating instructions. Failure to do so may result in personal injury or damage to the analyzer.

Heat: Situate and store the analyzer away from sources of heat.
Liquid and Object Entry: The analyzer should not be immersed in any liquid. Care should be taken so that liquids are not spilled into

and objects do not fall into the inside of the analyzer.
Handling: Do not use force when using the switches and knobs. Before moving your analyzer be sure to disconnect the wiring/power

cord and any cables connected to the output terminals located on the analyzer.

Maintenance

Serviceability: Except for replacing the oxygen sensor, there are no parts inside the analyzer for the operator to service.
Only trained personnel with the authorization of their supervisor should conduct maintenance.

Oxygen Sensor: DO NOT open the sensor. The sensor contains a corrosive liquid electrolyte that could be harmful if touched or
ingested, refer to the Material Safety Data Sheet contained in this Owner’s Manual. Avoid contact with any liquid or crystal type powder
in or around the sensor or sensor housing, as either could be a form of electrolyte. Leaking sensors should be disposed of in
accordance with local regulations.

Troubleshooting: Consult the guidelines in section 8 for advice on the common operating errors before concluding that your analyzer
is faulty. Do not attempt to service the analyzer beyond those means described in this Owner’s Manual.

Do not attempt to make repairs by yourself as this will void the warranty, as detailed by section 9, and may result in electrical shock,
injury or damage. All other servicing should be referred to qualified service personnel.

Cleaning: The analyzer should be cleaned only as recommended by the manufacturer. Wipe off dust and dirt from the outside of the
unit with a soft damp cloth then dry immediately. Do not use solvents or chemicals.

Nonuse Periods: Disconnect the power when the analyzer is left unused for a long period of time.

4

Advanced Instruments Inc.

Installation

Gas Sample Stream: Ensure the gas stream composition of the application is consistent with the specifications and review the
application conditions before initiating the installation. Consult the factory to ensure the sample is suitable for analysis. Note: In
natural gas applications such as extraction and transmission, a low voltage current is applied to the pipeline itself to inhibit corrosion.
As a result, electronic devices can be affected unless adequately grounded.

Contaminant Gases: A gas scrubber and flow indicator with integral metering valve are required upstream of the of the analyzer to
remove interfering gases such as oxides of sulfur and nitrogen or hydrogen sulfide that can produce false readings, reduce the
expected life of the sensor and void the sensor warranty if not identified at time of order placement. Installation of a suitable scrubber
is required to remove the contaminant from the sample gas to prevent erroneous analysis readings and damage to the sensor or
optional components. Consult the factory for recommendations concerning the proper selection and installation of components.

Expected Sensor Life: With reference to the publish specification located as the last page of this manual, the expected life of all
oxygen sensors is predicated on oxygen concentration (< 1000 ppm or air), temperature (77°F/25°C) and pressure (1 atmosphere) in
“normal” applications. Deviations are outside the specifications and will affect the life of the sensor. As a rule of thumb sensor life is
inversely proportional to changes in the parameters.

Accuracy & Calibration: Refer to section 5 Operation.
Materials: Assemble the necessary zero, purge and span gases and optional components such as valves, coalescing or particulate

filters, and, pumps as dictated by the application; stainless steel tubing is essential for maintaining the integrity of the gas stream for
ppm and percentage range (above or below ambient air) analysis; hardware for mounting.

Operating Temperature: The sample must be sufficiently cooled before it enters the analyzer and any optional components. A coiled
10 foot length of ¼” stainless steel tubing is sufficient for cooling sample gases as high as 1,800ºF to ambient. The maximum
operating temperature is 45º C on an intermittent basis unless the user is willing to accept a reduction in expected sensor life – refer to
analyzer specification - where expected sensor life is specified at an oxygen concentration less than 1000 ppm oxygen for ppm
analyzers and air (20.9% oxygen) for percent analyzers, but in all instances at 25°C and 1 atmosphere of pressure. Expected sensor
varies inversely with changes in these parameters.

Pressure & Flow

All electrochemical oxygen sensors respond to partial pressure changes in oxygen. The sensors are equally capable of analyzing the
oxygen content of a flowing sample gas stream or monitoring the oxygen concentration in ambient air (such as a confined space such
in a control room or an open area such as a landfill or bio-pond). The following is applicable to analyzers equipped with fuel cell type
oxygen sensors. With respect to analyzers equipped with Pico-Ion UHP and MS oxygen sensors, refer to the analyzer’s specifications.

Analyzers designed for in-situ ambient or area monitoring have no real inlet and vent pressure because the sensor is exposed directly
to the sample gas and intended to operate at atmospheric pressure, however, slightly positive pressure has minimal effect on accuracy.

Inlet Pressure: Analyzers designed for flowing samples under positive pressure or pump vacuum (for samples at atmospheric or
slightly negative atmospheres) that does not exceed 14” water column are equipped with bulkhead tube fitting connections on the side
of the unit (unless otherwise indicated, either fitting can serve as inlet or vent) and are intended to operate at positive pressure
regulated to between 5-30 psig although their particular rating is considerably higher. Caution: If the analyzer is equipped with an
optional H2S scrubber, inlet pressure must not exceed 30 psig.

Outlet Pressure: In positive pressure applications the vent pressure must be less than the inlet, preferably atmospheric.
Sample systems and flowing gas samples are generally required for applications involving oxygen measurements at a pressure other

than ambient air. In these situations, the use of stainless steel tubing and fittings is critical to maintaining the integrity of the gas
stream to be sampled and the inlet pressure must always be higher than the pressure at the outlet vent which is normally at
atmospheric pressure. Flow Through Configuration: The sensor is exposed to sample gas that must flow or be drawn through metal
tubing inside the analyzer. The internal sample system includes 1/8” compression inlet and vent fittings, a stainless steel sensor
housing with an o-ring seal to prevent the leakage of air and stainless steel tubing.

5

Advanced Instruments Inc.

Flow rates of 1-5 SCFH cause no appreciable change in the oxygen reading. However, flow rates above 5 SCFH generate backpressure
and erroneous oxygen readings because the diameter of the integral tubing cannot evacuate the sample gas at the higher flow rate.
The direction the sample gas flows is not important, thus either tube fitting can serve as the inlet or vent – just not simultaneously.

A flow indicator with an integral metering valve upstream of the sensor is recommended as a means of controlling the flow rate of the
sample gas. A flow rate of 2 SCFH or 1 liter per minute is recommended for optimum performance.

Caution: Do not place your finger over the vent (it pressurizes the sensor) to test the flow indicator when gas is flowing to the sensor.
Removing your finger (the restriction) generates a vacuum on the sensor and may damage the sensor (voiding the sensor warranty).
To avoid generating a vacuum on the sensor (as described above) during operation, always select and install the vent fitting first and
remove the vent fitting last.

Application Pressure - Positive: A flow indicator with integral metering valve positioned upstream of the sensor is recommended for
controlling the sample flow rate between 1-5 SCFH. To reduce the possibility of leakage for low ppm measurements, position a
metering needle valve upstream of the sensor to control the flow rate and position a flow indicator downstream of the sensor. If
necessary, a pressure regulator (with a metallic diaphragm is recommended for optimum accuracy, the use of diaphragms of more
permeable materials may result in erroneous readings) upstream of the flow control valve should be used to regulate the inlet pressure
between 5-30 psig.

Caution: If the analyzer is equipped with a H2S scrubber as part of an optional sample conditioning system, inlet pressure must not
exceed 30 psig.

Application Pressure - Atmospheric or Slightly Negative: For accurate ppm range oxygen measurements, an optional external
sampling pump should be positioned downstream of the sensor to draw the sample from the process, by the sensor and out to
atmosphere. A flow meter is generally not necessary to obtain the recommended flow rate with most sampling pumps.

Caution: If the analyzer is equipped with an optional flow indicator with integral metering valve or a metering flow control valve
upstream of the sensor - open the metering valve completely to avoid drawing a vacuum on the sensor and placing an undue burden
on the pump.

If pump loading is a consideration, a second throttle valve on the pump’s inlet side may be necessary to provide a bypass path so the
sample flow rate is within the above parameters.

Recommendations to avoid erroneous oxygen readings and damaging the sensor:

¾ Do not place your finger over the vent (it pressurizes the sensor) to test the flow indicator when gas is flowing to the sensor.

Removing your finger (the restriction) generates a vacuum on the sensor and may damage the sensor (thus voiding the sensor
warranty).

¾ Assure there are no restrictions in the sample or vent lines
¾ Avoid drawing a vacuum that exceeds 14” of water column pressure – unless done gradually
¾ Avoid excessive flow rates above 5 SCFH which generate backpressure on the sensor.
¾ Avoid sudden releases of backpressure that can severely damage the sensor.
¾ Avoid the collection of liquids or particulates on the sensor, they block the diffusion of oxygen into the sensor
¾ If the analyzer is equipped with an optional integral sampling pump (positioned downstream of the sensor) and a flow control

metering valve (positioned upstream of the sensor), completely open the flow control metering valve to avoid drawing a vacuum
on the sensor and placing an undue burden on the pump.

Moisture & Particulates: Installation of a suitable coalescing or particulate filter is required to remove condensation, moisture and/or
particulates from the sample gas to prevent erroneous analysis readings and damage to the sensor or optional components. Moisture
and/or particulates do not necessarily damage the sensor, however, collection on the sensing surface can block or inhibit the diffusion
of sample gas into the sensor resulting in a reduction of sensor signal output – and the appearance of a sensor failure when in fact the
problem is easily remedied by blowing on the front of the sensor. Consult the factory for recommendations concerning the proper
selection and installation of components.

- wipe away.

6

Advanced Instruments Inc.

Moisture and/or particulates generally can be removed from the sensor by opening the sensor housing and either blowing on the the
sensing surface or gently wiping or brushing the sensing surface with damp cloth. Caution: Minimize the exposure of ppm sensors to
air during this cleaning process. Air calibration followed by purging with zero or a gas with a low ppm oxygen concentration is
recommended following the cleaning process. Moisture and/or particulates generally can be removed from the sample system by
flowing the purge gas through the analyzer at a flow rate of 4.5-5 SCFH for an hour.

Mounting: The analyzer is approved for indoor use, outdoor use requires optional enclosures, consult factory. Mount as recommended
by the manufacturer.

Gas Connections: Inlet and outlet vent gas lines for ppm analysis require 1/8” or ¼” stainless steel compression fittings; hard plastic
tubing with a low permeability factor can be used percentage range measurements.

Power: Supply power to the analyzer only as rated by the specification or markings on the analyzer enclosure. The wiring that
connects the analyzer to the power source should be installed in accordance with recognized electrical standards. Ensure that is
properly grounded and meets the requirements for area classification. Never yank wiring to remove it from a terminal connection. AC
powered analog analyzers consume 5 watts, digital analyzers 50 watts without optional heaters. Optional 110V and 220V heaters AC
powered heaters consume an additional 100-150 watts; DC powered digital analyzers consume 30 watts, 40 watts with the optional DC
powered heater.

4 Features & Specifications

See last page, this page left blank intentionally.

5 Operation

Principle of Operation

The GPR-3500MO portable oxygen purity analyzer incorporates a unique advanced electrochemical galvanic fuel cell type sensor. The
portable oxygen purity analyzer is configured in an intrinsically safe design and meets the intrinsic safety standards required for use in
Class 1, Division 1, Groups A, B, C, D hazardous areas.

Advanced Galvanic Sensor Technology

The sensors are specific for oxygen. They measure the partial pressure of oxygen from low ppm to 100% levels in inert gases, gaseous
hydrocarbons, helium, hydrogen, mixed gases, acid gas streams and ambient air. Oxygen, the fuel for this electrochemical transducer,
diffusing into the sensor reacts chemically at the sensing electrode to produce an electrical current output proportional to the oxygen
concentration in the gas phase. The sensor’s signal output is linear over all ranges and remains virtually constant over its useful life.
The sensor requires no maintenance and is easily and safely replaced at the end of its useful life.

Proprietary advancements in design and chemistry add significant advantages to an extremely versatile oxygen sensing technology.
Sensors for low ppm analysis recover from air to ppm levels in minutes, exhibit longer life and reliable quality. The expected life of our
new generation of percentage range sensors now range to five and ten years with faster response times and greater stability. Another
significant development involves expanding the operating temperature range for percentage range sensors from -30°C to 50°C.

7

Advanced Instruments Inc.

The sensor employed by the GPR-3500MO is but one part of the proprietary advancements in sensor technology. It is the only
electrochemical galvanic sensor available that is capable measuring 100% oxygen on a continuous 24/7 basis.

Electronics

The signal generated by the sensor is processed by state of the art low power micro-processor based digital circuitry. The first stage
amplifies the signal. The second stage eliminates the low frequency noise. The third stage employs a high frequency filter and
compensates for signal output variations caused by ambient temperature changes. The result is a very stable signal. Sample oxygen is
analyzed very accurately. Response time of 90% of full scale is less than 10 seconds (actual experience may vary due to the integrity
of sample line connections, dead volume and flow rate selected) on all ranges under ambient monitoring conditions. Sensitivity is
typically 0.5% of full scale low range. Oxygen readings may be recorded by an external device via the 0-1V signal output jack.

Power is supplied by an integral rechargeable lead acid battery which provides enough power to operate the analyzer continuously for
approximately 60 days. Expect 8-10 hours service from a single battery charge when using the pump on a regular basis. An LED
located on the front panel provides a blinking 72 hour warning to recharge the battery. A 9VAC adapter (positive pole located on the
inside of the female connector) can be used to recharge the battery from a convenience outlet. The analyzer is designed to be fully
operational during the 8-10 hour charging cycle which is indicated by a second continuously lit LED.

Sample System

The GPR-3500MO is supplied with panel mounted flow meter for maximum portability. Users interested in adding their own sample
conditioning system should consult the factory. Advanced Instruments Inc. offers a full line of sample handling, conditioning and
expertise to meet your application requirements. Contact us at 909-392-6900 or e-mail us at [e-mail]

8

Advanced Instruments Inc.

Accuracy & Calibration

Single Point Calibration: As previously described the
galvanic oxygen sensor generates an electrical current
proportional to the oxygen concentration in the sample gas.

Absolute Zero: In the absence of oxygen the sensor exhibits
an absolute zero, e.g. the sensor does not generate a current
output in the absence of oxygen. Given these linearity and
absolute zero properties, single point calibration is possible.

Pressure: Because sensors are sensitive to the partial pressure
of oxygen in the sample gas their output is a function of the
number of molecules of oxygen 'per unit volume'. Readouts in
percent are permissible only when the total pressure of the
sample gas being analyzed remains constant. The pressure of
the sample gas and that of the calibration gas(es) must be the
same (reality < 1-2 psi).

Temperature: The rate oxygen molecules diffuse into the sensor is controlled by a Teflon membrane otherwise known as an 'oxygen
diffusion limiting barrier' and all diffusion processes are temperature sensitive, the fact the sensor's electrical output will vary with
temperature is normal. This variation is relatively constant 2.5% per ºC.

A temperature compensation circuit employing a thermistor offsets this effect with an accuracy of better than +
Operating Range of the analyzer) and generates an output function that is independent of temperature. There is no error if the
calibration and sampling are performed at the same temperature or if the measurement is made immediately after calibration. Lastly,
small temperature variations of 10-15º produce < 1% error.

Accuracy:

producing 'percent of reading errors', illustrated by Graph A below, such as +5% temperature compensation circuit, tolerances of
range resistors and the 'play' in the potentiometer used to make span adjustments and 2) those producing 'percent of full scale errors',
illustrated by Graph B, such as +
fact that other errors are 'spanned out' during calibration. Graph C illustrates these 'worse case' specifications that are typically used to
develop an transmitter's overall accuracy statement of < 1% of full scale at constant temperature or < 5% over the operating
temperature range. QC testing is typically < 0.5% prior to shipment.

Example: As illustrated by Graph A any error, play in the multi-turn span pot or the temperature compensation circuit, during a span
adjustment at 20.9% (air) of full scale range would be multiplied by a factor of 4.78 (100/20.9) if used for measurements of 95-100%
oxygen concentrations. Conversely, an error during a span adjustment at 100% of full scale range is reduced proportionately for
measurements of lower oxygen concentrations.

In light of the above parameters, the overall accuracy of an analyzer is affected by two types of errors: 1) those

1-2% linearity errors in readout devices, which are really minimal due to today's technology and the

5% (over the entire

9