Teledyne 311-D User Manual

INSTRUCTION MANUAL

FOR

TRACE OXYGEN ANALYZER

MODEL 311-D

RANGES: 0-100 PPM; 0-1000 PPM; 1% AND 100%

TELEDYNE ANALYTICAL INSTRUMENTS

16830 CHESTNUT STREET

CITY OF INDUSTRY, CALIF. 91749

TELEPHONE: [phone]

FAX: [phone]

TWX: [phone] TDYANYL COID

EASYLINK: 628-31862

Web: www.teledyne-ai.com

TABLE OF CONTENTS

MODEL 311D

1. INTRODUCTION 1

1.1 Description 1

1.2 Method of Analysis 1

1.3 Outstanding Features 1

1.3.1 Micro-Fuel Cell 1

1.3.2 Reliable Calibration 1

1.3.3 Integral Power Supply 2

1.3.4 Accuracy and Response 2

1.3.5 Compact Packaging 3

1.3.6 Circuit Description 3

2. SUPPORTING EQUIPMENT AND SERVICES 4

2.1 Sampling Equipment 4

2.2 Power Service 4

3. OPERATION 4

3.1 Introduction 4

3.2 Calibration 5

3.2.1 Calibration Procedure 5

3.3 Positive Pressure Sampling 6

3.4 Atmospheric Pressure Sampling 6

4. MAINTENANCE 7

4.1 Battery Power Supply Services 7

4.2 Routine Maintenance 7

4.3 Cell Replacement 7

4.4 Cell Warranty 8

5. TRANSDUCTION AND TEMPERATURE COMPENSATION 9

6. LEAK TESTING 9

SPECIFICATION DATA 10

APPENDIX - Effect of CO

on B-2C Cell Life 11

2

SPARE PARTS LIST 12
DRAWING LIST 13

1. INTRODUCTION

1.1 Description
portable trace oxygen analyzer which can be operated without an external power source, and
reliably calibrated without the use of cumbersome, questionable, “certified” calibration gases.

The instrument provides for trace oxygen analysis in decade steps ranging from 0-100 to 0-1000
ppm (full scale) plus a 0-1% and 0-100% calibration range that encompasses the known oxygen
concentration of atmospheric air (20.9%, or 209,000 ppm).

Sample oxygen is read from an extremely accurate digital panel meter (0.1% accuracy) whose
range of measurement is determined by the position of the range selector switch.

Sample gas is introduced and vented via a pair of swagelok quick-disconnect fittings that feature
integral shutoff valves that automatically close when the mating male fitting is withdrawn. The
fittings are an integral part of the measuring cell manifold, so that internal sample passage
volume is at an absolute minimum. Sample flow control, although not critical (0.1 to 10
liters/min.), must be accomplished with accessory equipment.

1.2 Method of Analysis
electrochemical transducer, which functions as a fuel cell; in this instance, the fuel is oxygen.
Oxygen diffusing into the cell reacts chemically to produce an electrical current that is
proportional to the oxygen concentration in the gas space immediately adjacent to the transducer
sensing surface. A two-stage solid state amplifier that features operational amplifiers whose
power consumption per unit is less than (5) milliwatts amplifies the linear, but minute, signal
produced by the transducer from trace oxygen. The dual stages of amplification provide enough
gain to read on the digital panel meter and use a thermistor- controlled network to compensate
for the positive temperature coefficient of the transducer.

1.3 Outstanding Features
Model 311-D:

1.3.1 Micro-Fuel Cell
transducer with no electrolyte to change or electrodes to clean. When the cell reaches the end of
its useful life, it is merely thrown away and replaced, as one would replace a worn-out battery in
a flashlight. The life of the cell is warranted by TAI (see Section 4.4) in a fashion similar to that
employed by the manufacturers of automobile batteries. This procedure guarantees the customer
compensation for failure of a given cell to perform as specified.

1.3.2 Reliable Calibration
the user to calibrate the instrument with the most economical, reliable
gas there is -- atmospheric air.

The special “CAL” range of the instrument is meant for calibrating the span in ambient air to

20.9% oxygen. By drawing air through the instrument (see the sample calibration procedure in
Section 3.2) reliable calibration can be achieved.

: The Teledyne Analytical Instruments (TAI) Model 311-D is a

: The sample oxygen is measured by a unique

: The following unique features are incorporated into the

: The Micro-Fuel Cell is a sealed electrochemical

: The unique qualities of the Micro-Fuel Cell allow

, abundant, standardization

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After the electronics have been properly zeroed (a one-time factory operation), the instrument
cannot produce an output indication in the absence of oxygen; therefore, the need for a “zero”
standardization gas is obviated.

1.3.3 Integral Power Supply
(DPM) requirements of the instrument amplifier are furnished by three internally-mounted 750
milliampere-hour nickel-cadmium batteries. Fully charged, these batteries will provide enough
power to operate the instrument continuously
overnight charge on a 2-day duty cycle should keep the original batteries usable for many years.
A “LOW BATTERY” indication is shown on the digital display.

An integral charging circuit and a detachable power cord are provided so that the batteries may
be recharged from any 50 or 60 cycle, 105 to 125 volt convenience outlets.

The instrument is designed to either sample or have its batteries recharged. Both operations
cannot be carried out simultaneously. TAI has deliberately interlocked the circuitry in this way.

Only when the selector switch is placed in the “OFF” position will the neon lamp on the back
plate of the 311D light up to indicate power to the battery charging circuit.

A current limiting resistor (53.2 ohms) is potted into the end of each battery. This assures that,
under no circumstances, can more than 80 milliamperes be switched or drawn from either battery
supply.

BATTERY CHECK

selector knob counter-clockwise to the battery test position and hold there; the switch is spring­loaded, and must be held. The meter should read more than 1600; otherwise, the batteries need
to be recharged. Release the Range Selector Switch, and it will automatically return to the
“OFF” position. When the batteries are set at a really low charge condition, the “LOW BATT”
warning is displayed. Caution should be taken not to discharge the batteries any further.

1.3.4 Accuracy and Response
of ±0.2% of full scale, or ±0.2 ppm, whichever is greater, at constant temperature. A ±5% of
reading accuracy is achievable throughout the operating temperature range of 30 to 125°F.

With a sample flowrate of 150 cc/min., 90% response is achieved in 10 seconds in all the
positions.

1.3.5 Compact Packaging
inch aluminum case that is equipped with a carrying handle and foot pads.

Access to the instrument interior is gained by loosening (ccw) the three 1/4” slot-head fasteners
on the back of the outer case. The case may then be detached from the control panel assembly.

: To determine the state of the rechargeable batteries, turn the range

: The differential power and digital panel meter

for a period of ca. 500 hours. Furthermore, an

: The Model 311D provides monitoring accuracy

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: The instrument is housed in a 6-1/8 x 9-1/2 x 5-5/8

Further disassembly may be accomplished by removing the backplate assembly from its four
mounting standoffs, and laying the two separated assemblies out as illustrated on the “Analyzer
Wiring Diagram”. The diagram is included among the drawings at the rear of the manual.

1.3.6 Circuit Description
transducer; its output current is in proportion to the concentration of the oxygen measured. A
current-to-voltage converter, A3, supplies an output voltage, whose level is set by the range
switch to the span pot. A thermistor varies the gain of amplifier A2 as the temperature of the
cellblock changes; this compensates for the change in output of the Micro-Fuel Cell due to
changes in temperature. The output of A2 is shown on the digital panel meter (DPM). Refer to
the schematic diagram.

The batteries are charged when the instrument is connected to the main power supply, and kept
in the off position. The batteries are charged at 80 mAmp, set by resistor R1. In the
measurement mode, amplifier A1b, which floats the ground at the center of the power supply,
controls the power supplied to the amplifier and the DPM.

The synthetic ground amplifier maintains a constant ratio of 1:1 between the negative and
positive power supplies. The constant ratio keeps the offset voltage of the amplifier from
changing as the battery voltage varies up and down. This prevents damage to the Micro-Fuel
Cell, due to oxidation caused by reverse-polarity charging. The synthetic ground is produced by
connecting the non-inverting input of amplifier A1b to the junction of R7 and R8 (which is at the
ground potential); the output of A1b is the synthetic ground. The resulting dual power supplies
have a constant ratio of:
Neg. supply/Pos. supply = R7/R8 = 1.

WARNING

cells may be damaged, and this will shorten the life of the battery. Always check the battery
charge before using the instrument.

If the battery voltage should drop to zero while the unit is operating, the FET switch Q1 shorts
the Micro-Fuel Cell; this protects the cell from damage or saturating with oxygen.

2. SUPPORTING EQUIPMENT AND SERVICES

2.1 Sampling Equipment
pressure and flowrate of the sample gas. For positive pressure applications, TAI suggests a
simple throttle valve, installed in the sample line between the sample point and the analyzer.
The flowrate should be limited to 0.1 to 10 liters/min. IMPORTANT: If a pressure regulator is

: Caution should be exercised! If the battery is discharged excessively, the battery

: A Micro-Fuel Cell (Class B-2C) is used as the

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: The customer must provide a means of controlling the

necessary or desirable, it must have a metallic diaphragm. Regulators with organic or plastic
diaphragms are permeable to oxygen, and if used in the sampling system, will lead to high
oxygen readings.

For atmospheric pressure sampling, connect a pump and flow control valve downstream
analyzer and draw (rather than push) the sample through the instrument.

TAI supplies three male disconnect fittings with the instrument; one for installation of the
customer’s sample line, one to be used to open the vent fitting of the instrument, and one
(equipped with a plastic tube) for drawing air through the unit for calibration purposes.

2.2 Power Service
capable of delivering a maximum of 1/4 ampere of current will be periodically
recharge the instrument’s battery power supply. An eight-foot, UL approved, 3-wire, detachable
power cord is provided with the instrument and should be stored in a safe place when not in use.
As a no-cost option, the 311D can be furnished with 220-volt, 50 or 60 Hertz charging power.

3. OPERATION

3.1 Introduction
instant use. The Micro-Fuel Cell is in place within the manifold, and prior to shipment the
manifold was purged with an inert gas to eliminate all but traces of oxygen from the internal
sampling system. The integral shutoff valves in the quick-disconnect sample fittings, if not
disturbed, will maintain this inert atmosphere within the manifold indefinitely. This can be
demonstrated by advancing the range selector switch to the 0-1000 ppm position.

When the range selector is advanced from the “OFF” position, power to the instrument’s
circuitry is established. The meter will instantly respond to the residual oxygen within the
integral sample passages.

It is impossible to achieve a “perfect” seal of the internal sample system, and what the meter is
indicating is the diffusion/consumption balance point of the internal sample system and the
micro-fuel cell.

This “balance” point, with a properly calibrated instrument, is always within the limits of the 100
ppm range. If the reading claims off the limits of this scale, a leak in the manifold assembly is
indicated.

TO EXTEND THE CELL LIFE AND MINIMIZE THE TIME REQUIRED TO MAKE
THE NEXT ANALYSIS, THE INSTRUMENT SHOULD ALWAYS BE PURGED WITH
THE SAMPLE OR AN INERT GAS PRIOR TO BEING TAKEN OUT OF SERVICE
FOR STANDBY OR STORAGE.

3.2 Calibration
cludes a definitive calibration cycle. TAI feels that the interval between calibrations should be

: A source of single-phase, 105 to 125 volt, 50 or 60 Hertz power,

: The Model 311D is delivered completely assembled and ready for

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: The inherently constant output of the cell during its useful life pre-

from the

required to