Teledyne 335 User Manual

Oxygen Alarm Monitor

INSTRUCTION MANUAL

FOR

Model 335 Series

Oxygen Alarm Monitor

DANGER

HIGHLY TOXIC AND OR FLAMMABLE LIQUIDS OR GASES MAY BE PRESENT IN THIS MONITORING SYSTEM.
PERSONAL PROTECTIVE EQUIPMENT MAY BE REQUIRED WHEN SERVICING THIS SYSTEM.
HAZARDOUS VOLTAGES EXIST ON CERTAIN COMPONENTS INTERNALLY WHICH MAY PERSIST FOR A

TIME EVEN AFTER THE POWER IS TURNED OFF AND DISCONNECTED.
ONLY AUTHORIZED PERSONNEL SHOULD CONDUCT MAINTENANCE AND/OR SERVICING. BEFORE

CONDUCTING ANY MAINTENANCE OR SERVICING CONSULT WITH AUTHORIZED SUPERVISOR/MANAGER.

TELEDYNE ANALYTICAL INSTRUMENTS

M24692

ECO# 99-0011

10/08/99

i

Model 335

Copyright © 1999 Teledyne Analytical Instruments

All Rights Reserved. No part of this manual may be reproduced, transmitted,
transcribed, stored in a retrieval system, or translated into any other language or computer
language in whole or in part, in any form or by any means, whether it be electronic,
mechanical, magnetic, optical, manual, or otherwise, without the prior written consent of
Teledyne Analytical Instruments (TAI), 16830 Chestnut Street, City of Industry, CA 91749-

1580.

Warranty

This equipment is sold subject to the mutual agreement that it is warranted by us free
from defects of material and of construction, and that our liability shall be limited to
replacing or repairing at our factory (without charge, except for transportation), or at
customer plant at our option, any material or construction in which defects become
apparent within one year from the date of shipment, except in cases where quotations or
acknowledgements provide for a shorter period. Components manufactured by others bear
the warranty of their manufacturer. This warranty does not cover defects caused by wear,
accident, misuse, neglect or repairs other than those performed by TAI or an authorized
service center. We assume no liability for direct or indirect damages of any kind and the
purchaser by the acceptance of the equipment will assume all liability for any damage
which may result from its use or misuse.

We reserve the right to employ any suitable material in the manufacture of our
apparatus, and to make any alterations in the dimensions, shape or weight of any parts, in
so far as such alterations do not adversely affect our warranty.

Important Notice

This instrument provides measurement readings to its user, and serves as a tool by
which valuable data can be gathered. The information provided by the instrument may
assist the user in eliminating potential hazards caused by his process; however, it is
essential that all personnel involved in the use of the instrument or its interface, with the
process being measured, be properly trained in the process itself, as well as all instrumenta­tion related to it.

The safety of personnel is ultimately the responsibility of those who control process
conditions. While this instrument may be able to provide early warning of imminent
danger, it has no control over process conditions, and it can be misused. In particular, any
alarm or control systems installed must be tested and understood, both as to how they
operate and as to how they can be defeated. Any safeguards required such as locks,
labels, or redundancy, must be provided by the user or specifically requested of TAI at the
time the order is placed.

Therefore, the purchaser must be aware of the hazardous process conditions. The
purchaser is responsible for the training of personnel, for providing hazard warning
methods and instrumentation per the appropriate standards, and for ensuring that hazard
warning devices and instrumentation are maintained and operated properly.

TAI, the manufacturer of this instrument, cannot accept responsibility for
conditions beyond its knowledge and control. No statement expressed or implied by this
document or any information disseminated by the manufacturer or its agents, is to be
construed as a warranty of adequate safety control under the user’s process conditions.

TELEDYNE ANALYTICAL INSTRUMENTSii

Oxygen Alarm Monitor

DANGER:

WARNING:

ELECTRICAL SHOCK HAZARD

Disconnect all power to this instrument before performing
any maintenance. The PCBs within the enclosure contain
dangerously high voltages sufficient to cause death or
serious injury. Do not rely on the power switch alone to
disconnect the AC power from the unit...DISCONNECT THE
AC POWER CORD FROM THE AC POWER SOURCE before
performing maintenance or placing your hands inside the
enclosure.

This instrument is designed to be operated in a nonhazard­ous area. It is the customer's responsibility to ensure that
proper training and understanding of the principles of opera­tion of this equipment is understood by the user. Since the
use of this instrument is beyond the control of Teledyne, no
responsibility by Teledyne, its affiliates and agents for dam­age or injury resulting from misuse or neglect of this instru­ment is implied or assumed.

Misuse of this product in any manner, tampering with its
components or unauthorized substitution of any component
may adversely affect the safety of this instrument.

CAUTION:

.

When operating this instrument, the doors must be closed
and all covers securely fastened. The gauges must be in
proper working order. Do not over-pressurize the system.

Read this manual before operating the instrument and ad­here to all warnings included in this manual.

TELEDYNE ANALYTICAL INSTRUMENTS

iii

Model 335

1 Introduction

2 Operational Theory

2.1 Method of Analysis........................................................... 2-1

2.2 Micro-Fuel Cell Sensor .................................................... 2-1

2.2.1 Principles of Operation............................................ 2-1

2.2.2 Anatomy of a Micro-Fuel Cell.................................. 2-2

2.2.3 Electrochemical Reactions...................................... 2-3

2.2.4 The Effect of Pressure............................................. 2-4

2.2.5 Calibration Characteristics ...................................... 2-4

2.3 Circuit Description............................................................ 2 -5

2.4 Alarms .............................................................................. 2-6

Table of Contents

3 Installation and Operation

3.1 Installing the Micro-Fuel Cell ........................................... 3- 1

3.2 Power and Signal Connections........................................ 3-1

3.2.1 AC and Battery Backed Standby Power................... 3-1

3.2.2 Installing the Rechargeable NiCad Batteries ........... 3-2

3.2.3 Signal Connections .................................................. 3-2

3.3 Calibration........................................................................ 3-3

3.4 Operation ......................................................................... 3-4

3.5 Cell Warranty ................................................................... 3 -4

3.6 Safety Checklist ............................................................... 3-4

3.7 Accessory Flow-Through Adapter.................................... 3-5

Appendix

Specifications......................................................................... A-1

Recommended Spare Parts List............................................ A-2

Drawing List ........................................................................... A-2

Material Safety Data Sheet.................................................... A-3

TELEDYNE ANALYTICAL INSTRUMENTSiv

Oxygen Alarm Monitor Introduction 1

Introduction

The Teledyne Analytical Instruments (TAI) Model 335 Oxygen
Alarm accurately measures the oxygen content of the atmosphere sur­rounding its sensor. The standard measurement range is 0-25% oxygen.
The alarm feature of the instrument incorporates two adjustable setpoints
to allow alarm warning under either of two independent oxygen level
conditions. The standard alarm indication is produced by both an audible
annunciator and a visual light, and when an alarm condition exists, a relay
is energized to switch a set of relay contacts. Both normally open and
normally closed circuits are provided by the Form “C” relay contacts;
consult the Interconnection Diagram at the rear of the manual to find the
interconnection terminals where the circuits can be accessed.

DANGER:

The instrument is designed as a safety monitor. However, it is the
responsibility of the user to establish whether or not the total system or
instrument, environment, alarm components and any other relevant devices
will actually assure safety in his/her particular circumstances.

The “Safety Checklist” outlined in the “Pre-Operation” section of this
manual should be treated as a guide only; it is up to the user to establish
practical safety precautions. Also, it is vital that operator’s understand and
test the operation of the complete system.

Consult the circuit-related drawings at the rear of the manual to find
information about circuit paths (schematic) and connecting points (wiring
and interconnection diagrams), as well as physical characteristics and
dimensions (outline diagram). These drawings reflect the exact design and
construction of your instrument.

Remove power from the system before opening the
instrument or attempting to perform any maintenance.

TELEDYNE ANALYTICAL INSTRUMENTS

1-1

1 Introduction Model 335

1-2

TELEDYNE ANALYTICAL INSTRUMENTS

Oxygen Alarm Monitor Operational Theory 2

Operational Theory

2.1 Method of Analysis

The analysis is specific for oxygen, i.e., the measuring cell will not
generate an output current unless oxygen is present in the sample gas.
Thus, the instrument has an absolute zero and no zero gas is required to
operate the analyzer.

The measuring cell has the ability to respond accurately to the pres­ence of oxygen irrespective of flowrate. TAI recommends using ambient
air as a span gas or, if that is not possible, using a known calibration gas of
about 80% of the range of interest value.

The measuring cell (U.S. Patent #3,429,796) is a solid-state mainten­ance-free structure that carries a TAI guarantee for performance and usable
life. The cell consumes oxygen from the gas surrounding it and generates
a proportional microampere current. The low level signal is then amplified
by a solid-state operational amplifier. The resulting DC signal is suitable
for driving a high impedance recording device, a temperature compen­sation circuit for the cell and an integral 0-100µA meter. The output signal
is linear over the specified ranges of analysis.

2.2 Micro-Fuel Cell Sensor

2.2.1 Principles of Operation

The oxygen sensor used in the Model 335 is a Micro-Fuel Cell (MFC)
designed and manufactured by TAI. It is a sealed plastic disposable elec­trochemical transducer.

The active components of the MFC are a cathode, an anode and the
15% aqueous Potassium Hydroxide (KOH) electrolyte in which they are
immersed. The cell converts the energy from a chemical reaction into an
electrical potential that can produce a current in an external electrical
circuit. Its action is similar to that of a battery.

TELEDYNE ANALYTICAL INSTRUMENTS

2-1

2 Operational Theory Model 335

There is, however, an important difference in the operation of a
battery as compared to the MFC: in the battery, all reactants are stored
within the cell, whereas in the MFC, one of the reactants (oxygen) comes
from outside the device as a constituent of the sample gas being analyzed.
The MFC is therefore a hybrid between a battery and a true fuel cell. (All
of the reactants are stored externally in a true fuel cell.)

2.2.2 Anatomy of a Micro-Fuel Cell

The MFC is a cylinder only 1¼" in diameter and 1¼" thick. It is
made of extremely inert plastic (which can be placed confidently in practi­cally any environment or sample stream) and is effectively sealed, though
one end is permeable to oxygen in the sample gas. At the permeable end a
screen retains a diffusion membrane through which the oxygen passes into
the cell. At the other end of the cell is a contact plate consisting of two
concentric foil rings. The rings mate with spring-loaded contacts in the
sensor block assembly and provide the electrical connection to the rest of
the analyzer. Figure 2-1 illustrates the external features.

mfcouts.wmf

Figure 2-1: Micro-Fuel Cell

mfc-xsec.wmf

Figure 2-2. Cross Section of a Micro-Fuel Cell

2-2

TELEDYNE ANALYTICAL INSTRUMENTS