Edgetech OxyTrans Operator's Manual

OxyTrans

Loop Powered Two Wire
Oxygen Transmitter

OPERATORS MANUAL

19 Brigham Street Unit 8
Marlborough, MA 01752
508-263-5900 Fax: [phone]
www.edgetechinstruments.com
[e-mail]

Rev. A April 2009

OxyTrans

QUICK STARTUP GUIDE

STARTUP

1. Using the supplied Mounting Kit, mount the OxyTrans in
position to measure the desired gas.

Caution: The cell must be mounted vertically with Digital

Display at the top.

2. Connect input and output tubing. See Manual for proper tubing

materials. Shutoff valves should be installed on both sides of
the sensor.

3. Connect loop power supply, using cable supplied.

4. Connect data acquisition system or other series load if

required.

5. Allow sufficient equilibration time before recording data.

TABLE OF CONTENTS Page

1.0 Quick Startup Guide

2.0 Commitment to Quality 3

3.0 Introduction 4

3.1 General Description 4

3.2 Micro Fuel Sensor 4

3.3 The Effect of Pressure 4

3.4 Calibration Characteristics 5

3.5 Standard Configurations 5

3.6 Options and Accessories 6

4.0 Installation 8

4.1 Mounting 8

4.2 Plumbing 8

4.3 Electrical Connections 9

5.0 Operation 11

5.1 Digital Display 11

5.2 Analog Output 11

6.0 Maintenance

6.1 Calibration 12

6.2 Out of Service Procedure 13

6.3 Troubleshooting 13

6.4 Cell Replacement 14

7.0 Specifications 18

8.0 Appendix 19

8.1 Warranty 20

8.2 Oxygen Cell Housing Drawing 21

8.3 Intrinsically Safe Barrier (Optional) 22

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LIST OF ILLUSTRATIONS Page

3-1 Cell I/O Curve 5
3-2 Standard Configurations 6
4-1 Mounting Kit 8
4-2 Mounting the Transmitter 9
4-3 Electrical Connections 10
5-1 Digital Display 11
6-1 Calibration Adjustment 12

LIST OF TABLES Page

3-1 Standard Factory Ranges 6

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2.0 EDGETECH INSTRUMENTS INC.'S COMMITMENT
TO QUALITY

To Our Customers:

Thank you for purchasing one of our products. At Edgetech
Instruments Inc., it is our policy to provide cost-effective products and
support services that meet or exceed you requirements, to deliver
them on time, and to continuously look for ways to improve both. We
all take great pride in the products we manufacture.

We want you to be entirely satisfied with your instrument. The
information contained in this manual will get you started. It tells you
what you need to get your equipment up and running, and introduces
its many features.

We always enjoy hearing from the people who use our products. Your
experience with our products is an invaluable source of information
that we can use to continuously improve what we manufacture. We
encourage you to contact or visit us to discuss any issues whatsoever
that relate to our products or your application.

The Employees of Edgetech Instruments Inc.

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3.0 INTRODUCTION

3.1 GENERAL DESCRIPTION

The Edgetech Instruments Inc. OxyTrans 2-wire 4 to 20 mA Loop Powered
Oxygen Transmitter consists of two sub-systems:

1. The Analyzer Unit, which is an electro-chemical fuel sensor designed

for measuring oxygen.

2. The Electronics Unit, which provides sensor signal conditioning, digital

display, and electrical analog outputs.

The gas to be measured is transported to the sensor membrane of the Micro
Fuel sensor. This sensor is an electro-chemical and galvanic cell that transforms
the oxygen in the measured gas into an electrical current.

The Electronics Unit measures this electrical signal, providing visual and
electrical information to the operator, directly in either parts-per-million of oxygen
(ppm O2), or as a percentage of the total measured gas (%O2).

3.2 MICRO FUEL SENSOR

The oxygen sensor is a sealed plastic disposable electrochemical sensor. The
active components are a cathode and an anode, which are immersed in a 15%
aqueous KOH electrolyte solution. When oxygen in the sample gas is sensed by
the membrane, the cell converts the resulting chemical reaction into an electrical
current change. Its action is similar to that of a battery, with one important
difference. In a battery, all reactants are stored within the cell. In the oxygen
sensor, one of the reactants, oxygen, comes from outside the device as a
constituent of the sample gas being analyzed.

3.3 THE EFFECT OF PRESSURE

In order to determine the amount of oxygen present in the gas sample, it is

necessary that the gas diffuse into the cell under constant pressure, by Dalton’s

Law. If the total pressure increases during a measurement, the rate that oxygen
reaches the cathode through the diffusing membrane will also increase. The
electron transfer, and therefore the resulting measured output current, will
increase even though the oxygen concentration in the sample has not changed.

Therefore, it is important that the sample pressure at the fuel cell remain
constant during measurements.

4

0

10

20

30

40

50

60

70

80

90

100

0 0,2 0,4 0,6 0,8 1

oxygen concentration %

output zell in µA

3.4 CALIBRATION CHARACTERISTICS

Since the total pressure of the sample gas at the input of the measuring cell
is constant, a convenient characteristic of the cell is that the current produced in
an external circuit is directly proportional to the rate at which oxygen molecules
reach the cathode, and this rate is directly proportional to the concentration of
oxygen in the gaseous mixture. In other words it has a linear characteristic
curve, as shown in Figure 3-1. An advantage is that measuring circuits do not
have to compensate for nonlinearities.

In addition, since there is zero output in the absence of oxygen, the
characteristic curve has close to an absolute zero (within ± 1 ppm oxygen).
In practical application, zeroing is still used to compensate for the
combined zero offsets of the cell and the electronics. The electronics is
zeroed automatically when the instrument power is turned on.

Figure 3-1 Characteristic Input/Output Curve for the Oxygen Cell

3.5 STANDARD FACTORY CONFIGURATIONS

The Edgetech Instruments Inc. OxyTrans series of transmitters are available in a
number of
convenient configurations. These include both vertical and horizontal mounts, so
that the digital display may be viewed either from the top or from the front.
Intrinsically Safe barriers are also available if required.

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A number of standard ranges are available. These include:

RANGE

PARTS-PER-MILLION

PERCENT OXYGEN

0 to 10

X

0 to 100

X

0 to 1000

X

0 to 10,000

X

0 to 1

X

0 to 25

X

Table 3-1 Standard Factory Ranges

3.6 OPTIONS AND ACCESSORIES

Other standard configurations include a Panel Mount unit with optional safety
barriers. A Portable unit is available in a carrying case with a built-in sampling
system, including a flow meter, flow adjustment valve, sintered filter, vacuum
pump, and power supply. Also available is an Explosion-Proof (ATEX approved)
version. A unit with electrical interface compatible with the Hart Protocol is a
standard option. Additional ranges are available on special order. Some ranges
provided in the past include 0 to 20,000 ppm, 0 to 50,000 ppm, and 0 to 100%
O2. See Figure 3-2 below.

Figure 3-2a Explosion-Proof Unit Figure 3-2b Vertical Mount

Figure 3-2c Horizontal Mount Figure 3-2d Portable Unit

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