Bacharach TLV sniffer User manual

hIstruction 23-9613
Rev. No. 2
January, 1990
:
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L INSTRUCTIONMANUAL
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WARNING!
Because thisinstrumentis used to detect and monitormaterialsand conditionswhichare listedby
OSHAor others aspotentiallyhazardous topersonnel andproperty, the informationin thismanual
mustbe fullyunderstoodand utilizedto ensurethattheinstrumentisoperatingproperlyand isboth
usedand maintainedintheproper manner byqualifiedpersonnel.Aninstrumentthatisnotproperly
calibrated,operatedandmaintainedbyqualifiedpersonnelislikelytoprovide erroneousinformation,
whichcouldprevent user awareness of a potentiallyhazardoussituationfortheinstrumentuser,other
personnel and property.
If, after reading the informationin this manual, the user has questions regarding the operation,
applicationormaintenance oftheinstrument,supervisoryortrainingassistanceshouldbe obtained
before use. Factoryassistanceis available bytailing [phone].
Bacharach, Inc.
625 Alpha Drive, Pittsburgh, PA 15238 [phone]
Printed in U.S.A. @Registered Trademarks

Bacharach, Inc., warrants to Buyer that at the time of delivery this
Product will be free from defects in material and manufacture and
will conform substantially to Bacharach Inc.'s applicable
specifications. Bacharach's liability and Buyer's remedy under this
warranty are limited to the repair or replacement, at Bacharach's
option, of this Product or parts thereof returned to Seller at the
factory of manufacture and shown to Bacharach Inc.'s reasonable
satisfaction to have been defective; provided that written notice of
the defect shall have been given by Buyer to Bacharach Inc. within
one (1) year after the date of delivery of this Product by Bacharach,
Inc.
Bacharach, Inc. warrants to Buyer that it will convey good title to
this Product. Bacharach's liability and Buyer's remedy under this
warranty of title are limited to the removal of any title defects or,
at the election of Bacharach, to the replacement of this Product or
part-s thereof that are defective in title.
The warranty set forth in paragraph 1 does not apply to parts the
Operating Instructions designate as having a limited shelf-life or as
being expended in normal use.
THE FOREGOINGWARRANTIESARE EXCLUSIVEANDARE GIVEN ANDACCEPTEDIN
LIEU OF (i) ANY ANDALL OTHERWARRANTIES,EXPRESSOR IMPLIED,
INCLUDINGWITHOUTLIMITATION THE IMPLIED WARRANTIESOF
MERCHANTABILITYAND FITNESS FORA PARTICULARPURPOSE:AND (ii> ANY
OBLIGATION, LIABILITY, RIGHT, CLAIM OR REMEDYIN CONTRACTOR TORT,
WHETHEROR NOTARISING FROMBACHARACH'SNEGLIGENCE,ACTUALOR
IMPLIED. The remedies of the Buyer shall be limited to those
provided herein to the exclusion of any and all other remedies
including, without limitation incidental or consequential damages.
No agreement varying or extending the foregoing warranties, remedies
or this limitation will be binding upon Bacharach, Inc. unless in
writing, signed by a duly authorized officer of Bacharach.
NOTE: Fuses, batteries and sensors are expendable items not covered
by the warranty.
NOTICE
This manual contains proprietary information that
shall not be reproduced or copied in whole or in
part as the basis for manufacture of items herein
described.

.
ADDENDUM ,i
Instruction 23-9613
TLV Sniffer@
Rev. No. 2
January, 1990
USE OF DILUTION PROBE23-7355 WITH TLV SNIFFER
Dilution probe 23-7355 has an O-ring covering holes designed to admit fresh
air to dilute, by a factor of 10, any gas sample passing through the probe.
With the O-ring moved to expose the dilution holes, the 1O:l dilution ratio
enables the TLV Sniffer to indicate concentrations up to 100,000 ppm, thus
accommodating sample concentrations above the normal 10,000 ppm limit of the
Sniffer.
DETENTWITH 10 TO 1 AIR
DILUTION HOLES.
MOVABLEO-RING SHOWNIN AIR-DILUTION
POSITION. SLIDE O-RING TO COVERDILUTION
HOLESTO OBTAIN UNDILUTEDSAMPLES.
It must be remembered that, when using this probe in the dilution mode, all
meter indications should be considered as approximate, only. This is true
because of several variable factors which can affect the probe operation,
such as:
1. The actual dilution ratio is dependent upon the flow rate of the
sample. The flow rate is affected by battery charge, speed of the pump,
cleanliness of the probe, condition of the probe filter, etc.
2. The actual dilution ratio is dependent upon the quality of the air
which provides the dilution. If the dilution holes are ingesting combustible
gases rather than fresh air, the ppm indication of the Sniffer will vary
significantly from that of an indication obtained with fresh air entering
the dilution holes.
WARNING:At the extreme, of course, if the dilution holes and
the probe tip are sampling from the same atmosphere, no dilution
actually occurs. In that instance, if perfect dilution is assumed
when interpreting meter indications, an error of 1000% is incurred.
Addendum 1 to Instruction 23-9613
Rev.
1, January 1990
@RegIstered Trademarks

REMRMBER:
@For proper dilution, only fresh air should enter the dilution holes.
0 Multiply all meter indications by a factor of 10 when using the probe
in the dilution mode.
0 All meter readings in the dilution mode should be considered as
approximate, only.
0 Don't forget to re-cover the dilution holes with the movable O-ring
to obtain undiluted gas samples.
-
-
Bacharach, Inc.
625 Alpha Drive, Pittsburgh, PA 15238 [phone]

.
NICKEL-CADMIUM BATTERY MAINTENANCE
DO:
1.
Recharge new NiCads before use. It is a good idea to cycle them once or
twice before normal operation. This requires three steps: (1) fully charging
the NiCads, (2) discharging until the unit ceases functioning or indicates low
battery power, and (3) fully recharging (12-16 hours).
2. Put NiCads through a charge cycle at least once a month when they are not
in use. NiCads function best when they function frequently.
3: Prevent "memory" from occurring by running the NiCads through a full
discharge/charge cycle every week or two (once a month at least).
4. Match charge time to use on about a two to one ratio (e.g., if you use
the NiCads for four hours
, .charge them for about eight hours).
DON'T:
1. Do not use new NiCads without putting them through a full charge.
2. Do not attempt to use NiCads (or leave the instrument "0N")when the cells
' are fully discharged. To obtain proper instrument operation, and to prevent
NiCad damage, the cells must be recharged before further use.
3. Do not overcharge:
a. Never leave NiCads charging for more than 16 hours.
b. Do not charge over an entire weekend.
4. Do not attempt to charge other types of batteries in a NiCad charger or
to charge NiCads in a charger other than one designed specifically for NiCads.
Issue Date: October 1981
P/N 51-9480

TECHNOTE
EXPLANATION:
The Nickel-Cadmium battery (NiCad) can best be thought of as an energy
reservoir. Provided that it is properly filled with energy, it will-supply
that energy at a useful rate for many applications. However, underfilling or
overfilling the reservoir can cause serious problems, including the destruc-
tion of the system. It is the purpose of this bulletin to explain how NiCads
should be mafntained to insure that they will last for the hundreds and even
thousands of energy transfers for which they are designed.
Most of the NiCads used in portable instruments are designed to carry an
energy supply sufficient to power the instrument for about 6-8 hours. Because
of electrical and chemical losses, more energy must be put into the NiCads
than is drawn from them as they discharge while being used. Therefore,
it
normally takes from 12-16 hours of charging time to refill depleted NiCads
completely. If you use an instrument for 6-8 hours a day and then charge it
each night for 12-16 hours, you should obtain hundreds of cycles of NiCad use.
However, if you use an instrument for varying periods of time each day, or if
you use it only occasionally, then the charging requirements ,becomemore
complex.
Due to some peculiar characteristics of NiCads, the manner in &ich they.are
charged is crucial in .detertnining how well and how long they will function.
There are several things that can go wrong with NiCads, and it is important to
know what they are:
1. If NiCads are used when they are almost totally out of energy, they can
be destroyed. This happens because the internal ionic structure of one of the
NiCad cells reverses polarity. Consequently, do not continue to use an
instrument with NiCads when the battery monitoring system indicates low or
depleted batteries. The instrument should be turned off and recharged before
being used again.
2. If NiCads are overcharged, they can be destroyed. NiCads work by means
of an internal chemical-electrical process, involving interaction of gases and
metals. WhenNiCads are charged, gases are built up in the cells. If over-
charging occurs, the gas pressure in the cell can become too high, causing
' internal damage in the cell and the possibility of an explosion. None of
Bacharach's NiCad systems should be left in a. charging condition for more than
16 hours; and, in general, 12-14 hours of charging should be sufficient. Do
not leave an instrument charging for an entire weekend, as it will almost
certainly cause overcharging, a reduction of the NiCad life, and even a safety
hazard. Also, the charge time required
to refill the NiCad reservoir is re-
lated to how far discharged the NiCad is. Thus, if you have a NiCad system
designed to power an instrument for eight hours, and you use it for only two
hours, you do not need to recharge it for a full 12-14 hour period. Instead,
3-4 hours of charging should be sufficient to return the unit to a full charge.
3. NiCads 'lose energy when not in use. NiCads have a shorter shelf life
than other kinds of batteries. They will lose 25% of their charge in one
month of non-use, 50% in three months, and 85% in five months. This means two
things: (1) you should apply a full charge to the NiCads supplied with a new
instrument before you use the instrument for the first time, and (2) if an
instrument remains idle for one month or more, it should be charged before
use.
*
9-2

TECHNOTE
NiCads tend to develop a "memory." For example, if a set of Nicads is
for three hours every day and then recharged, the internal ionic
4.
used
structure will eventually tend to "memorize" that cycle and the NiCads will
readily yield only three hours of service. Once this "memory" occurs, no
amount of recharging will overcome it. It will be necessary to discharge the
batteries almost completely (which may take considerably longer than normal)
. and then to recharge them in order to defeat the "memorized" ionic structure.
Sometimes this cycle (depletion/recharge) will have to be repeated two or
three times before the "memory" can be overcome.
.
The best way to insure against "memory" is to fully cycle the NiCads periodi-
cally. That is, once every week or two, leave the instrument on until the
battery indication shows a low reading or a recharge requirement (be careful
not to leave the unit on for too long), and then charge the unit fully over-
night (12-16 hours). This will revitalize the entire internal ionic structure
of the NiCads and will prevent "memory" from occurring.
9-3

a
SECTION1
CONTENTS PAGE
iz-
.
DESCRIPTION
PURPOSEAND FUNCTIONS. ...................... l-l
Toxicity Warning Function
................... l-l
PPMMeter...........................l- 1
. Search Function
........................ l-1
Continuous Self-Monitoring. .................. l-l
PRINCIPLE OF OPERATION...................... l&l
SENSITIVITY RANGES.
...................... .1-2
ACCURACYANDRELIABILITY
..................... 1-2
PHYSICAL DESCRIPTION ...................... : 1-3
Instrument and Case ....................... l-3
Air Sampling Mechanisms .................... l-3
Combustible Gas Detector.
................... 1-4
AUXILIARY EQUIPMENT. ....................... 1-4
Probe and Hose. ........................ 1-4
Earphone. ...........................
l-4
Batteries
........................... l-4
Battery Charger ........................
l-5
Recorder. ........................... l-5
CONTROLS.............................
1-5
Mode Selector ......................... l-5
ADJUSTMENTS............................
1-5
Meter Zero Mechanical Adjustment Screw. ............ l-5
Meter Zero Coarse Adjustment Screw.
.............. l-6
Meter Zero Fine Adjustment Knob ................ l-6
Gain Potentiometer Adjustment Screws.
............. l-6
Alarm Level Potentiometer Adjustment Screw.
.......... l-6
Recorder Level Potentiometer Adjustment Screw ......... 1-6
.
SECTION2 2-l
PRE-OPERATIONCALIBRATIONSANDADJUSTMENTS
BATTERYTEST ........................... 2-l
SETTING METERPOINTER TO ZERO. .................. 2-1
SETTING METER POINTER DEFLECTION (GAIN CALIBRATION) ........ 2-2-5
RESETTINGALARMRESPONSE
..................... 2-6
SETTING RECORDING.LEVEL. ..................... 2-7
SECTION&
OPERATION
MONITORINGTOXICITP. . . . . . . . . . . . . . . . . . . . . . . . 3 -1
Direct Readings and Alarm . . . . . . . . . . . . . . . . . . . 3-l
Converting Hexane-calibrated Meter ppm Readings to ppm
Readings for Other Gases. . . . . . . . . . . . . . . . . . . 3-l
Converting ppm Readings to Percent Lower Explosive Limit. . . . 3-3
LOCATINGGAS LEAK SOURCES. . . . . . . . . . . . . . . . . . . . . 3-4

SECTION5 4-l
MAINTENANCEANDREPAIRS
SYMPTOMSANDREMEDIES (TABLE). . . . . . . . . . . . . . . . . . . 4-1
REPLACINGFAULTY COMPONENTSAND PARTS. . . . . . . . . . . . . . :4-5
Replacing Batteries . . . . . . . . . . . . . . . . . . . . . . 4-5
Replacing Detector. . . . . . . . . . . . . . . . . . . . . . . 4-5
Replacing Printed Circuit Board . . . . . . . . . . . . . . . . 4-5
Replacing Sample Pump . . . . . . . . . . . . . . . . . . . . . 4-6
SECTION5
.5-l
REPLACEMENTPARTSLIST . . . . . . . . . . . . . . . . . . . . . . i . 5-1
ILLUSTRATIONS
FIGURE
l-l
2-l
2-2
2-3
2-4
3-l
3-2
4-l
TABLE
3-l
4-l
Troubleshooting Procedures. . . . . . . . . . . . . . . . . . . 4-l
TLV Circuitry Adjustment Potentiometer Locations. ....... l-7
Bacharach Code 51-7199 Gas Calibration Kit. ..........
2-3
Calibration Gas Transfer Assembly ............... 2-3
Locating and adjusting R-13 on PPMX 100 Position .......
2-5
Locating and adjusting R-3 for Certified Gas Indication .... 2-6
Use of Dilution Probe and Hose Assembly and I In-line
Filter and Trap Assembly. .................. 3-2
Conversion Curves Showing Relationship of PPM
Concentrations of Various Gases to Percent
L.E.L. Equivalents. . . . . . . . . . . . . . . . . . . . a . 3-4
TLV Sniffer Chassis Subassembly Showing Miniature
PumpAssembly in Disassembled Position. . . . . . . . . . . . 4-7
TABLES
.
Multiplying Factors for Converting PPMMeter Readings
of Hexane-calibrated Instruments to PPM
Concentrations of Other Gases . . . . c . . . . . . . . . . . 3-3

l-l
SECTION1
DESCRIPTION
.
PURPOSEAND FUNCTIONS
Toxicity Warning Function
The portable TLV Sniffer is an extremely sensitive combustible gas and vapor
sensing instrument with an overall detecting sensitivity range,of from 1 to
10,000 parts of gas or volatile flammable vapor per million parts of air (by
volume). The instrument is equipped with an audible (beep) alarm that can
be set to sound at any desired level of gas concentration to warn
automatically of toxic concentrations of gas. Connections are provided for
an auxiliary earphone for use in noisy areas to assure that audible warnings
will be heard.
PPMMeter
--
A meter reading directly in parts per million (ppm) allows instant visual
determination of toxicity danger as readings are compared to published
standard Threshold Limit Values. The instrument can be calibrated to read
directly in parts per million for any one of many kinds of combustible
gases. Factory calibration is for hexane unless otherwise specified, though
readings from other gases and vapors may be interpreted easily by means of
reading conversion cur(7es (in OPERATIONSection, this manual).
Search Function
In addition to its primary function of indicating ppm combustible vapor
concentrations and toxicity levels, an ultrasensitive "search" range of from
1 to 100 ppm makes the TLV Sniffer especially useful for locating hard-to-
find gas leaks. A hand-held probe attached to the instrument can be moved
in the direction indicated by rising meter readings to point out quickly the
source of escaping gas.
Continuous ~Self-Monitoring
Other functions provided in the TLV Sniffer circuitry for continuous self-
monitoring purposes include a continuous, audible note of warning in
response to failing batteries and to excessive negative drift in signal
voltage due to malfunctioning detector circuit components. A 45-second time
delay circuit is incorporated to prevent the sounding of a false alarm due
to temporary voltage imbalances during thebrief warmup period after the
instrument mode selector switch has been set to operate the instrument.
PRINCIPLE OF OPERATION
-
To detect and measure concentrations of combustible gas in the air, the TLV
Sniffer catalytically oxidizes gas in a pumped-in sample of air by means of
a catalyst-coated resistance element. The resistance of this element
changes with changes in heat that are proportional to the amount of oxidized
gas, thereby altering the electrical balance of the catalytic element as

1-2
compared to the resistance of a reference element. Both the catalyst-coated
("active") element and the reference element are incorporated in a
Wheatstone Bridge circuit in such a way as to produce an electrical output
proportional to their differences in resistance. Since any changes in air
sample temperature and humidity affect both active and reference elements
equally, the electrical signal output is proportional to the concentrations
of combustible gas or vapor in the sample of air (expressed involumetric
terms as ppm). However, sudden changes in humidity may affect the zero
reading on the X-l range. The instrument should, therefore, be zeroed at
the same R.H. prevailing during use.
The audible alarm response at the desired gas concentration ppm level is
accomplished by comparing the gas concentration signal level with an
internal reference voltage. Amplification of the difference between signal
and reference voltages will, at a preset level, operate the audible alarm.
SENSITIVITY RANGES
The TLV Sniffer circuitry and meter provide readings from 0 - 10,000 ppm in
three range settings. The first, with MODESELECTOR switch set at PPM X
100, indicates from 0 to 10,000 ppm on the meter. The second range, with
MODESELECTOR set at PPMX 10, gives readings between 0 to 1000 ppm. The
third range setting, at MODE SELECTORposition PPM X 1, provides readings
from 0 to 100 ppm. Each range setting requires an easily made adjustment of
the ZEROADJUST control knob on the instrument front panel to set the meter
indicating pointer to zero. Span adjustments for full-scale pointer
deflection within each range are made periodically as necessary by means of
three gain potentiometers located within the instrument.
ACCURACYAND RELIABILITY
The extent to which meter readings correspond to actual parts per million of
combustible gases in sampled air depend upon (1) the internal electrical
stability of the instrument, (2) proper calibration of the instrument on gas
mixtures of known concentration, and (3) purity of the air sample used for
meter pointer zero setting.
The electrical stability of TLV Sniffer circuitry is best demonstrated with
the MODESELECTORswitch set at PPM X 1. In this most sensitive range of
the instrument, all gas signal voltages are multiplied by 100, so that a O-
to l-millivolt signal actually drives the meter pointer with the necessary 0
to 100 millivolts to achieve full-scale deflection. Thus a pointer
deflection of l/100 sensitivity of the TLV circuitry to minute electrical
changes, the meter needle shows practically no deflection as power is
applied to the speaker for the audible beep signal.
Given this electrical stability, any lack of correspondence between actual
parts per million of combustible gas and the meter readings would be much
more Likely to arise from improper calibration of the instrument, or from
setting meter zero in the presence of impure air than from instability of
the TLV Sniffer circuitry.

Calibrated for hexane gas (a relatively high-energy gas) at the factory, the
TLV Sniffer should also provide accurate ppm readings for benzene, toluene,
and other gases of similar combustion rates. Conversion curves aid in
correctly interpreting readings from combustible gases that release energy
at different rates.
Thus, purity of the air sample used for meter pointer zero settings'is by
far the most important factor in obtaining accurate ppm readings. Ideally,
the pointer should be zeroed in the PPM X 1 mode of operation, where
deviations from zero would be more apparent because of maximum deflection.
In this range, however, extreme sensitivity causes the instrument to respond
to the slightest traces of gas. Wisps of cigarette smoke, fumes from
passing autos, and subtle air contaminations from many other sourcesmay
affect the zero setting. The extent to which zero readings are biased
because of air sample impurities will be reflected in less accurate readings
of actual gas concentration ppm. Frequently, an apparent negative drift of
the meter pointer may be caused by carrying the instrument to an area of
fresher air after zeroing the meter inadvertently on air that was not as
pure.
PHYSICAL DESCRIPTION
Instrument and Case
--
The TLV Sniffer is housed in a sturdy, brushed-aluminum and blue, wrinkle-
finished plastic case. An attractively designed carrying handle serves also
as an adjustable support stand and shoulder strap holder. Weighing 5-l/2
lbs., the compact 8-x6-l/2-x3-l/4-inch instrument is as convenient to carry
as a transistor radio. A front panel
, easily visible with the instrument in
carrying position, contains a meter reading directly in ppm, and control
knob for range selection and zero setting of the indicating meter pointer.
The side panels of the instrument provide plugs and connectors for an air
sample probe, earphones, battery charger, and recorder. Removal of ten
screws holding the rugged plastic cover to the rigid aluminum case gives
access to batteries and calibration adjustment controls located within the
interior of the case.
TLV Sniffer Models
The TLV Sniffer is available as a standard model 0023-7350, for use in areas
known to be free of combustible gases and vapors, or as an intrinsically
safe model 0023-7356, for use in hazardous areas designated Class I,
Divisions 1 or 2 by the National Electrical Code. Model 0023-7356 has been
certified to be intrinsically safe by the Factory Mutual Laboratories.
Air Sampling Mechanisms
The TLV Sniffer air sampling system consists of a short intake connection
leading directly into an interior aluminum air chamber holding the detector,
a six-inch length of tubing connecting the chamber and a miniature sample-
drawing pump, and a three-inch length of tubing to an exhaust port on the
left side of the instrument
*
case.

1-4
Combustible Gas Detector
The combustible gas detector consists of an "active" catalytic-coated -\.
resistance element to oxidize combustible gas, and an identical second
resistance element without the catalyst coating which provides a "reference" 0
resistance value unaltered by the oxidation of combustible gas. Since both
operate at approximately equal temperatures, only changes in gas content of
sampled air cause differences in resistance between the two to produce 4
signals to the meter and gas alarm circuits. Both active and reference
elements are protected within a porous bronze cylinder that plugs into a
mounting block attached with four screws to the air chamber block. The
.
three-pronged mounting block connects inturnto a cylindrical plug with
wires that connect to circuitry on the instrument circuit board.
AUXILIARY EQUIPMENT
Probe and Hose, 0023-7243, and Dilution Probe and Hose, 0023-7355
--
A five-foot-long flexible hose and probe assembly, for sampling air at
specific points to find exact locations of gas leaks, attaches to a fitting
on the left side of the case by means of a snap-fitting, spring-loaded
collar that can be drawn back with one hand, A cottondustfilter within
the probe protects the sample drawing lines and chamber from intrusion of
dust and dirt. The dilution probe 0023-7355 has an O-ring covering holes
designed to admit air to dilute the sample 10 times. With O-ring moved to
expose dilution holes, the instrument reads up to 100,000 ppm to accommodate
sample concentrations above the normal 10,000 ppm limit. (See Figure 3-l.)
An in-line filter and trap assembly 23,-7341 is available for use in dust-
or moisture-laden atmospheres.
Earphones
An earphone set of lOO-ohm impedance may be attached to an earphone jack
plug on the right side of the TLV Sniffer case wherever noise in an area to
be tested obscures the audible signal from the speaker of the instrument.
The earphone circuit does not cutout the audible speaker signal when the
earphone is attached, but rather provides a second way to hear the signal
where noise conditions so require.
Batteries
For standard model TLV Sniffer: The portable TLV Sniffer standard model is
powered by six D-size dry-cell batteries inserted in tubes and spring clamps
within the instrument case at the rear. Though
any kind of D cells maybe
used, nickel-cadmium rechargeable batteries are recommended for longest
uninterrupted service (six to nine hours of continuous service). The
instrument circuitry is so designed that an audible tone sounds when battery
power falls below that required to sustain gas detection operations.

1-5
For intrinsically safe model: The Intrinsically Safe battery pack is
similar to above, but the battery consists of six nickel-cadmium cells
connected by welded links to prevent arcing. The cell assembly is enclosed
0
in a rivet-sealed, high-impact, plastic
wire-wound resistors that limit current
.-. conditions to levels below that which
mixtures of combustible gas and air.
Battery Charger
W
housing with protective fuses and
capacity even under short-circuit
would ignite the worst possible
A compact battery charger (230 VAC: #0023-7353; 115 VAC: #0023-7230) with
a plug-in connector may be attached to a jack provided in the right side of
the instrument case. For stationary testing, the TLV Sniffer may be
operated with the charger connected. For portable operations, the charger
may be used to rejuvenate batteries within the instrument overnight, The
intrinsically safe battery packmay be recharged either in or outside the
instrument.
Recorder
A recorder (range: O-100 mv; impedance: 10,000 ohms or greater) may be
connected to the TLV Sniffer for use if variations in combustible gas levels
are to be recorded for study or legal data. Recording is more suitable for
the PPM X 100 and PPM X 10 mode ranges. The ultrasensitive PPM X 1 "search"
range, responsive from 1 to 100 ppm of gas, is not as suitable for an
accessory recorder because of the small magnitude of the signal and the
potentially rapid fluctuations of the signal within the range in response to
small changes in detected quantities of combustible gas.
CONTROLS
Mode Selector
The MODE SELECTOR control knob at lower right on the instrument panel
operates a rotating gang switch with an OFF position, a battery test switch,
and three range-selector switch positions that allow a choice among three
sensitivity ranges for readings of 0 - 100 ppm, 0 - 1000 ppm, or 0 - 10,000
ppm on the meter scale.
ADJUSTMENTS
Meter Zero Mechanical Adjustment Screw
--
The meter pointer mechanical adjustment screw is located within the
instrument on the back side of the meter barrel near the - terminal. This
adjustment screw is factory set, and does not ordinarily require subsequent
attention. Any adjustment of this screw should be done with the MODE
SELECTORknob turned to the OFF position.

l-6
Meter Zero Coarse Adiustment Screw (Figure l-1)
--
The met er pointer coarse adjustment is accomplished by means of a small
potenti .ometer adjustment screw located immediately under the ZEROADJUST
knob at lower left on the instrument panel. In fresh air, with power on, 0
with the MODE SELECTOR control knob set to PPM X 100, and with the ZERO
ADJUST knob turned to midpoint, this screw should be slowly turned to
position the pointer to zero on the meter scale.
Meter Zero Fine Adiustment Knob (Figure l-1)
---
In the presence of fresh air, the ZERO ADJUST knob at lower left on the .
instrument panel may be turned to.adjust the meter pointer to zero -- first
for the PPM X 100 range, then the PPM X 10 range, and lastly for the PPM X 1
range -- just before using the instrument to detect combustible gas. If
adjustment of this control does notbringthe pointer to zero, the coarse
zero-adjustment screw directly below may be turned to provide a greater
latitude of fine-adjust control. If the coarse adjustment eventually fails
to provide latitude for the fine-adjust control to operate, in all
probability the replacement of an exhausted detector element is indicated.
Gain Potentiometer Adiustment Screws (Figure l-1)
Three gain potentiometer adjustment screws accessible with the instrument
cover removed, are located on the circuit board at lower right within the
instrument case. With sample calibration gas of known concentration applied
to the air sample intake of the instrument, these screws are turned to
adjust amplifier gain for the correct amount of pointer deflection across
the meter scale. (See OPERATIONSection.) Separate potentiometer screws,
marked X10, X100, and Xl, are provided for each of the three scales
available by means.of the MODESELECTORknob.
Alarm Level Potentiometer Adjustment Screw (Figure 1-l)
The alarm level adjustment screw may be turned to set the audible alarm to
respond at any desired degree of pointer deflection across the meter dial.
The standard factory setting, which causes the alarm to respond at a meter
reading of 50, may be reset to correspond to the ppm Threshold Limit Value,
or to any arbitrary figure.
Record Level Potentiometer Adiustment Screw (Figure l-1)
The level of signal outputs to an accessory recorder may be set by turning
the adjustment screw marked "RECORDER"on the potentiometer assembly within
the instrument case at bottom right.

Alarm Trigger Point
.
-Adjuster (x2)(w/ 1
(NOTE: Standard
model fflustra.ted.
\.
Adjuster locations typical
for intrinsically safe
\/f Fine Zero Adjust (R26\
/ i’
model also. ) ,;
Voltage Adjuster (R20)
Offset Adjuster (RP3)
Figure l-l. TLV Circuitry Adjustment Potentiometer Locations.

2-l
PRE-OPERATION
SECTION2
CALIBRATIONSANDADJUSTMENTS
Prepare the TLV Sniffer Combustible Gas Detector for operation in accordance
L with the following steps:
BATTERYTEST
* Test battery as follows: Turn MODESELECTORknob from OFF position to BATT
TEST ,position, Meter pointer should come to rest in BATTERYGOODrange of
meter scale. (Both a meter reading below BATTERYGOODrange and an audible
signal warn of batteries too weak to sustain normal operation.)
SETTING METER,POINTERTO ZERO
--
Set pointer to meter zero as follows:
1.
2.
3.
4.
5.
6.
i
7.
t
Attach air sampling probe connector to instrument intake on left side of
case by pulling back spring collar of connector , pressing connector over
intake, and releasing spring collar,
Place TLV Sniffer inpositionin whichmeter indications willberead
(usually in meter-up position).
NOTE: Heat distribution from active and reference filaments of the
detector sensor changes from vertical to horizontal position. The
resulting change in electrical balance between elements causes a shift
in pointer zero from one position to the other.
Set MODE SELECTOR switch to PPM X 100 and operate instrument for 10
minutes to allow circuits to stabilize.
In fresh air, set ZERO ADJUST knob at midpoint (five full turns from
either extreme position). If fresh air is not available, use Bacharach
Kit #51-7199 to apply known pure air to the Sniffer intake (instructions
in kit).
Turn coarse adjustment screw, located under
ZERO ADJUST knob, to move
meter pointer to zero on the meter scale.
Turn MODESELECTORto PPM X 10 position and turn ZEROADJUSTknob to set
pointer to zero.
Turn MODESELECTORto PPM X 1 position and turn ZEROADJUSTknob to set
pointer to zero.
NOTE: The TLV Sniffer is extremely sensitive in the PPMX 1 range.
~02 from breath too close to the intake, cigarette smoke, auto fumes,
etc., can interfere with accurate setting of the pointer to meter zero,

2-2
SETTING METERPOINTER
Quantitative Gas Test (Refer to Figures 2-1, 2-2, 2-3 and 2-4)
DEFLECTION (GAIN CALIBRATION)
To ensure proper operation and to check calibration, it is necessary
periodically check the instrument against a known, standard blend
calibrating gas.
to
a
of
i
The Bacharach Code 51-7199 Gas Calibration Kit and optionally available Code
51-1120 Certified Gas Cylinder containing 500 PPM Hexane-in-air are readily
available to meet this requirement. I
Refer to Figure 2-1, the Calibration Kit consists of the following:
Item No.
Code No. Description Qtre
1 51-1201
2 06-6163
3 03-5393
4 03-4318
5 03-5532
6 03-6351
7 51-1127
Optional items may be
8 51-1120
9. Not 51-7131
Shown
Flowmeter Mtg. Bracket
Flowmeter
Quick Connect Ftg.
Regulator
Tee 3/16" (plastic)
Rubber Tubing
Barbed Hose Ftg. (connected to
Regulator Assembly)
ordered separately:
Cylinder Hexane-Air mixture
(certified 500 PPM)
Zero Calibration Gas (Compressed Air)
1.
1
1
1
1
5 ft.
1
1
1
Refer to Figure 2-2 and connect the gas transfer assembly as shown, making
:
certain all connections are air-tight. Use the retaining clips (2 each) to
mount Flowmeter (06-6163) to its Mounting Bracket (51-1201). Make certain
to connect rubber tubing at the base inlet connection on the Flowmeter, then
to the barbed fitting on the Regulator and to the Quick Connect fitting
previously installed on the TLV Sample-In (inlet fitting). Turn Regulator
Valve (03-4318) fully counterclockwise (closed position) before attempting'
to screw regulator into calibration gas tank.
NOTE:
DONOTOPENREGULATORVALVEAT THIS TIME.

-
.
Figure Z-l. Bacharach Code 51-7199 Gas Calibration Kit
Figure 2-2. Calibration Gas Transfer Assembly
Properly Hooked Up.
2-3