Bascom_turner GAS-ROVER VGI-201 User manual

BASCOM-TURNER
INSTRUMENTS
GAS-ROVERDETECTORS
OPERATION MANUAL
NATURAL GAS, CARBON MONOXIDE AND
OXYGEN DETECTORS
Part Number OM-0717

CAUTION
Personnel who operate, calibrate, or repair this instrument must first read and fully
understand this manual in its entirety.
For use in Class I, Division 1, Group D atmospheres (Propane and Methane).
These products have not been tested for intrinsic safety in oxygen enriched
atmospheres.
Change batteries, service, and use the USB interface only in areas known to have
non-hazardous atmospheres.
LIMITED WARRANTY
Bascom-Turner Instruments warrants Gas-Rover Detectors to be free from defects
in materials and workmanship for one year following the date of shipment. This
limited warranty applies to the original purchaser of the Detector and is not
transferable except by Bascom-Turner's authorized Distributors.
The instruments described in this manual are produced with standard commercial
parts, any of which may fail under some circumstances. Although the probability of
such failure is low, it is not zero. Accordingly, all personnel using such instruments
must be trained to recognize instrument malfunctions and to have such instruments
repaired promptly. Bascom-Turner offers no warranty that failures will not occur –
only that when theyoccur, theywill bepromptly cured with thefollowing procedure:
During the limited warranty period, we will repair or replace, at our option, any
defective products or parts at no additional charge. A return merchandise
authorization (RMA) number must be obtained prior to returning a detector to
Bascom-Turner. A detector returned to Bascom-Turner with probe and water-
block filter, shipping prepaid, will be repaired, calibrated and returned second day
air. Warranty repairs do not include pump cleaning, filter replacement and
calibration. All replaced parts and products become the property of Bascom-Turner
Instruments.
This limited warranty does NOT extend to any Detectors which have been damaged
as a result of accident, abuse, modification, misuse such as failure to follow the
operating instructions provided by Bascom-Turner Instruments, or other
contingencies beyond our control. No other warranty is expressed or implied.
Bascom-Turner is not liable for consequential damages.

TABLE OF CONTENTS
FEATURES
SPECIFICATIONS
PART 1. OPERATION
1. The Gas-Rover Detectors.......................................................................................
1
2. Essential Operating Practice ..................................................................................
2
3. Operational Description.........................................................................................
4
4. Instrument Checks..................................................................................................
8
5. Interference from Other Gases, Liquids, or RFI....................................................
9
6. Change of Batteries................................................................................................
10
7. Probes.....................................................................................................................
11
8. Routine Maintenance .............................................................................................
12
Appendix 1: Main Key Functions.......................................................................
14
Appendix 2: The Gas-Rover in Mobile Surveys.................................................
14
PART 2. SETUP AND CALIBRATION
1. Setup.......................................................................................................................
15
2. Further Setup Parameters.......................................................................................
16
3. Calibration..............................................................................................................
17
PART 3. THE USB INTERFACE
1. Downloads .............................................................................................................
18
2. Reports...................................................................................................................
20
3. Maintenance...........................................................................................................
22
PART 4. MAINTENANCE
1. Sensor and Pump Installation.................................................................................
24
ACCESSORIES AND SPARE PARTS
i

ii
FEATURES
The Gas-Roverportable methane, and combined methane, carbon monoxide and oxygen
detectors are intrinsically safe, microprocessor based instruments designed to test ambient air and
flue gas over a wide temperature range.
These detectors have many features for easy and reliable operation:
•PPM Measurement of Natural Gas with Catalytic Combustion Sensors
A calibrated ppm range up to 10,000 ppm of natural gas.
•Measurements Over the Full Range of Gas
The instruments detect methane over the full range of methane up to 100% GAS. Peak
and current readings are displayed simultaneously.
•Survey and Truck Survey
Two operating modes with quick response and high sensitivity make it easy to find gas
leaks during walking or truck surveys.
•Bar Holing
Peak and sustained bar-hole readings are automatically displayed after gas is pumped
for a precise, fixed time.
•Automatic Data Storage
Automatic storage of time and mode-stamped data readings. Automatic storage the last
24 calibrations. Automatic generation of reports.
•Automatic Calibration
Calibration is performed automatically using Bascom-Turner's calibration gas.
•Automatic Sampling
An intrinsically safe, built-in pump automatically samples ambient air, flue gas, and
bar hole gas.
•Automatic Self-Tests
Automatic checks of battery, sensors, and pump. Tests for blockage and for tight
connection of probe to instrument.
•Audible and Visual Alarms
Audible and visual alarms individually set. Continuous monitoring of natural gas, and
(optionally) CO and oxygen.
•Easy-to-Read, Backlit, Bright Display
A bright, large LCD display is easy to read both indoors and outdoors.
•Easy-to-Use
Simple, intuitive operation without complicated or confusing displays. A brief
operating manual is stored onboard.
•A Tough Package and a Light Weight
Housed in a high impact case, the instruments weigh only 24 ounces.

SPECIFICATIONS
Gases Detected Natural Gas (Methane)
Carbon Monoxide (CO) [Optional]
Oxygen (O2) [Optional]
Hydrogen Sulfide (H2S) [Optional]
Sensors Dual Catalytic Combustion (CH4)
Thermal Conductivity (CH4)
Electrochemical (CO, H2S, O2)
Ranges
GAS 0 to 10,000 ppm CH4 by volume
0 to 100% CH4 byvolume
PPM CO 0 to 2000 ppm carbon monoxide
% O2 0 to 40% by volume
PPM H2S 0 to 100 by volume
Resolution
GAS 1 ppm from 0 to 40,000 ppm
0.05 vol % from 0 to 5 vol %
1.0 vol % from 5 to 100 vol %
CO 1 ppm
O2 0.1 vol %
Warm-Up Time 60 seconds
Response Time: CH4: 0.6 seconds (Survey)
2 seconds (Monitor)
CO: 45 seconds
O2: 60 seconds
Operating Temp. -20oC to 40oC (0oF to 105oF)
Storage Temperature -40oC to 60oC (-40oF to 140oF)
Data Storage
And
Reports
24 Calibrations
2 to 3 months readings (typical)
Exposure and Bar-Hole Measurements,
Calibration History, Sensor Sensitivity,
Operational Periods by User and Unit ID,
Humidity 0 to 95% RH (non-condensing)
Power Supply Two C-size Alkaline or
Two C-size Rechargeable NiMH
Office Reports Continuous Operating
Time per Battery Set 10 hours typical (25oC)
Accuracy CH4:
(0º to 35ºC) 2% of reading 20 ppm
0.1% to 5%; 2.0% to 100 vol %
Weight 24 oz. (680 g)
CO: 5% of reading 10 ppm
O2: 0.2% vol %
iii

1
PART I. OPERATION
1.
THE GAS-ROVER DETECTORS
This manual describes the operation of the family of Gas-Rover detectors for natural gas,
carbon monoxide and oxygen:
Detects natural gas and displays it as PPM, %LEL and % GAS
Detects natural gas and displays it as PPM and % GAS
Detects natural gas and carbon monoxide and displays as PPM, % LEL and
% GAS, and PPM CO
Detects natural gas and carbon monoxide and displays PPM and % GAS
and PPM CO
Detects natural gas and oxygen and displays PPM, % LEL and % GAS, and
% Oxygen
Detects natural gas and oxygen and displays PPM and % GAS and
%Oxygen
Detects natural gas, CO, and oxygen and displays PPM, % LEL and % GAS,
PPM CO and % Oxygen
Detects natural gas, CO, and oxygen and displays PPM and % GAS, PPM
CO and % Oxygen
Detects natural gas, CO, and oxygen and displays PPM and % LEL, PPM
CO, PPM H2S and % Oxygen
Detects natural gas, CO, and oxygen and displays PPM and % GAS, PPM
CO, PPM H2S and % Oxygen
All models display gas in ppm in the Survey and Truck Survey modes.
All models may be used to test ambient air and bar holes for natural gas and locate gas
leaking from pipes and other conduits. All models which detect carbon monoxide (CO) may be
used to test for CO in ambient air, flue gas, and gases given off by appliances.
A detector alerts the user acoustically and visually, by "flashing" the symbol(s), for
detected gas(es), whose concentration exceeds preset limits. Visual alarms are displayed in-
between readings. For example, the display will flash "CO", approximately every two seconds,
in-between normal Monitor mode displays. If the concentration of natural gas also rises above its
alarm limit, the display will flash “GAS”, then a normal Monitor mode display, then "CO", and so
on. Simultaneously, the sound alarm will be on.
Visual alarm symbols are “GAS” for natural gas, "CO" for carbon monoxide. "Low
Oxygen" for low oxygen, and "High Oxygen" for high oxygen.
Factory set alarm limits are 1.0% methane, 35 ppm CO, and 19.5% for low and
23.0% for high oxygen.
No alarms are given in the Bar Hole, Survey, and Truck Survey modes. However, in the
Survey and Truck Survey modes the acoustic element (buzzer) will sound if gas is detected above
a user selected value (see Part 2, Section 1). The low battery warning is given in all modes.
Model
VGI-201
-
Model
VGI- 211
-
Model
VGC-301
-
Model
VGC-311
-
Model
VGO-321
-
Model
VGO-322
-
Model
VGA-411
-
Model
VGA-412
-
Model
VGA-611
-
Model
VGA-612
-

2
WARNING: On a call, turn the instrument on outdoors, not indoors.
2.
ESSENTIAL OPERATING PRACTICE
Gas-Rover detectors are easy to use. A detector is turned on by pressing the left button; its
operation is controlled by three buttons whose function is shown on the display. The middle button
generally toggles “Mute” on and off. Double-clicking the middle button turns the backlight
continuously ON or OFF, depending on its previous state.
Pump. Gas-Rover detectors have a built-in pump and depend on this pump for their
operation. If the pump is not functioning normally, the instrument will not function properly. It
is therefore essential to check the pump each time the instrument is turned on.
Pump Test: Connect the probe you plan to use and turn the instrument on. After the
display shows “Block Intake”, block the probe at its intake to show "Pump OK".
If "Pump OK" does not appear, tighten all connections and repeat the test. If a block is still
not observed, remove the probe and block directly the inlet. If "Pump OK" still does not appear,
return the instrument for repair.
A pump test can be carried out as above at any time during normal operation of the
instrument. If there is any indication that the pump is not operating normally, the instrument
should not be used until repaired.
Filters. Dust and water-block filters protect the sensors and the pump from dust and
accidental intake of liquid water. Just as a car would not be operated without air and fuel filters,
do not operate a detector without a filter on the probe. Operation without this filter will
eventually degrade the sensors and the pump. It also voids the limited warranty.
It is essential that the filter be replaced monthly or sooner if it turns brown. Operation
without a filter will degrade the natural gas sensor and will void the warranty. Filters are available
from Bascom-Turner in packages of five, Part No. WF-505.
Models VGA-611 and VGA-612 require special filters available from Bascom-Turner in
packages of five, Part No. WF-705.
Zero Check. All sensors drift to some extent over time. Sensor drift is corrected by
zeroing if the drift is within 0.1% vol. GAS (and 10ppm CO if the unit is equipped with a CO
sensor). If the drift is outside these limits, “NO GO”is displayed and the user is asked to autozero
the unit in “clean” outdoor air. The unit will re-zero unless the zero has drifted over 1% vol. GAS
(or 20ppm CO if the unit is equipped with a CO sensor), in which case the instrument must be
checked by a trained professional (the sensor may need replacement). Zero adjustment must be
done in clean air, for example, outdoor, otherwise a systematic error may be introduced in
subsequent measurements.
Test and Calibration. Gas-Rover detectors must be calibrated periodically with gas of
known composition. The sensors depend on catalysts which lose activity during use. The
necessary frequency of calibration depends on actual use and on the concentration of catalyst
poisons, if any, in the sampled gas. This concentration is, of course, not generally known.
A detector can be tested with methane bump gas, available P/N: BG-211 (100ppm in air).
Such tests merely verify that the gas sensor(s) are in operating condition. To verify and adjust, if
necessary, their sensitivity they must be calibrated.

3
WARNING: All gases detected by a particular instrument are monitored continuously
only in the Monitor mode.
WARNING: Each detector responds to the gases for which it was designed. Other toxic
or dangerous gases may not be detected.
WARNING: Only methane is detected in the Survey Mode.
WARNING: Catalytic combustion sensors do not respond in inert or reducing
atmospheres. Also, they should not be used for detecting combustible dusts
or mists.
A detector can be automatically calibrated in approximately one minute using Bascom-
Turner's calibration gas (2.5% CH4 and 100 ppm CO in air). Given the ease and speed of automatic
calibration, it pays to calibrate as frequently as possible, and certainly, at least monthly.
Accuracy. A properly operating and calibrated detector will respond with the specified
accuracy. If combustible gases other than the gas used for calibration are likely or suspected, the
instrument cannot be relied upon to give a proper indication of their concentration and hence of
how close to their combustible limits they may be. For example, the detector responds quite
differently to gasoline, to methane, and to propane. Accordingly, readings of % LEL (or its
equivalent in percent gas) refer only to the calibration gas and can be relied upon only in this
respect in assessing an atmosphere sampled by the detector. Furthermore, concentrations
displayed by the detector refer to a local sample at the tip of the instrument probe. Low gas
concentrations at one spot do not necessarily mean that the gas concentration is low throughout a
wider area.
Safety. These instruments measure the concentration of natural gas in air and give, more
generally, an indication of the presence of other combustible gases. When used by trained
personnel, they constitute one element for assessing the safety, or lack thereof, of a particular
atmosphere. However, they must not be relied upon by themselves for judging safety; all
other significant factors must be taken into account. As noted previously, the measured
concentration refers only to the immediate vicinity of the probe –concentrations in a wider area
may be significantly different. A trained technician should consider possible interferences,
physical or chemical, and be aware that calibrated values are only valid in air. If other gases,
including inert gases such as carbon dioxide are present, the measurements may not be reliable.
Finally, although there are built-in safeguards, a specific instrument may malfunction. It is
therefore imperative that other indicators, including, for example, odorant levels, must be taken
into account.

4
3.
OPERATIONAL DESCRIPTION
To conserve the batteries, turn the instrument OFF when not in use.
The instrument is controlled by three push button switches whose function changes with
each particular display (see Appendix 1). The function of each push button is shown on the display
in each case. In general, the middle button silences the beeper (“mutes” the instrument).
Startup Sequence. To turn the instrument on, press the left switch. A series of screens is
automatically displayed preparatory to entering the first operational mode, viz. “Survey”. Along
the way, a number of specialized screens can be used to access specialized functions.
The first screen shows the Model Number and the second displays gases detected by the
instrument and provides access to the USB interface (see Part 3) or to a display of the serial
number. The next screen shows the date and time. To edit the date or time, press the right “Edit”
button. The first digit of the hour will begin flashing and can be changed from 0 to 1 or 1 to 0 by
pressing the right “Update” button. Pressing the “Next” button advances the flashing digit which
can then be edited (or not) by pressing the right (or left) button, and so on. The same screen
provides access to a short manual by pressing the left “Help” button.
Following the Edit/Help screen, the pump is tested (“Block Pump” screen). If no block is
detected in 40 seconds, “Check Probe” is displayed, followed by “Remove Probe and Block
Intake” and finally “Repair Pump” followed by an automatic turning off of power.
The next display suggests a “Calibrate by [a date thirty days from the date of the last
calibration]” and an opportunity to calibrate (see Part 2, Calibration). If calibration is not chosen,
the instrument proceeds to enter the operational mode of “Survey” (see below).
The period of thirty days between calibrations is only a default value. The instrument
should be calibrated as often as possible, ideally every day. In any case, if poisoning of the natural
gas sensor or some other problem is suspected, the instrument should be promptly checked by
calibration with CAL Gas (see Part 2, Calibration).
Backlight. Pressing any button backlights the display for 20 seconds. To backlight any
display, press the middle button twice (double click). The backlight remains on until a new display
is entered or the middle button is double-clicked again. An exception to this procedure is during
bar holing (middle button initiates sampling). Pressing the middle “Go” button automatically
backlights the display long enough (60 seconds) to read the results.
Turning the Instrument Off. The instrument can be turned off from a number (but not
all) displays. Such places are obvious when a particular button is marked “Off.” In all such cases
the screen accessed by pressing “Off” requires a second operation (“Yes”) to actually turn the
instrument off. This sequence guards against accidental turning off.
When a direct “Off” button is not available, you may follow the procedures suggested below:
1.
At the USB access display, press the left “USB” button and then after the new
screen, the right “Off” button.
2.
During warm-up of the Survey mode, press the left “BH” button, then “Go”, and
then “Stop” (as soon as it appears) and then “Off.”

5
WARNING: The operation check is NOT equivalent to calibration and cannot be usedas
a substitute for calibration.
If two or more bars are consistently absent, replace the natural gas sensor or
return the instrument for repair.
CAUTION:
Operational Modes. The instrument operates in four distinct modes: “Survey”, “Truck
Survey”, “Bar Hole” and “Monitor”. An operating mode may be entered from another by pressing
the appropriate button either during warm-up or regular operation. For example, the Bar Hole
Mode can be selected when the instrument is first turned on by pressing the left “BH” button during
the warm-up period for the Survey Mode.
Survey: Connect an appropriate probe and power the unit. Following the preliminary
displays (see above), “Survey PPM” is shown for about 20 seconds. At the end of the warm-up
period “Operation Check” is available. To use it, present a source of at least 100ppm methane in
air to the probe intake. The Rover will automatically carry out the operation check and, if
satisfactory, will display “Operation Check OK”. If the check is not satisfactory, a “Please
Calibrate” message will appear. Calibration can be carried out as described in Part 2.
The Operation Check is offered when the instrument is first turned on. It is not offered
when the Survey mode is re-entered subsequent to bar-holing or monitoring. The time window
for carrying out the calibration check is 30 seconds; the test can be bypassed by pressing the
“Override” button in the initial screen or subsequently in the “Please Calibrate” screen.
After the instrument enters the Survey mode, it shows the concentration of gas in air in
parts per million by volume (ppm). The beeper will sound if the ambient concentration of gas rises
above a user selected value (see Part 2, Section 1). The factory set value is 10ppm. If it is desirable
to silence the beeper during a leak survey, the middle switch mutes the instrument (“Mute”appears
on the display). If the gas concentration is over 10,000 ppm (1% gas by volume), the unit
automatically enters the Monitor mode (see below).
Under some circumstances, it may be necessary to re-zero the survey mode. If a “fresh”
zero is required, for example, if the zero has drifted with the result that the instrument shows a
reading when sampling clean air, press the right switch after raising the probe away from the
ground, then press the right “Zero” button. The reading will be reset to zero within a few seconds.
The
Symbol. The symbol depicted here is used in the “Survey” mode to indicate
sensitivity at any particular instant. In general, sensitivity is an inverse function of background
noise –the lower the noise, the greater the sensitivity. The noise is primarily thermal and is caused
by convection.
Under most circumstances, all three vertical bars should be present. If the background
noise increases, one or more bars will be missing and in extreme circumstances, the whole symbol
may disappear. If the noise level rises so that more than two vertical bars are deleted, the
instrument should be allowed to return to its normal state by holding it steady for about two to
three seconds.
Survey by Truck: If a survey is to be conducted by truck, turn the instrument on as above
and carry out a calibration check. Connect the instrument, using an appropriate filter, to the
sampling system of the truck (see Appendix 2) and select the Truck mode.

6
WARNING: If a check is to be made for trace amounts of gas, for example around the
foundation of a structure, the Survey or the Monitor –not the Bar Hole -
mode should be selected.
The Truck mode is faster and more sensitive than the Survey mode and as such, it may
require occasional re-zeroing. To re-zero, press the right key and then choose “Zero” by pressing
the right key again.
Survey to Truck Survey and Truck Survey to Survey: Once either Survey or Truck
Survey modes have been entered, the transition from one to the other is relatively rapid (20
seconds). Either can be selected from the other by using the right button in each screen and
selecting Survey or Truck, as the case may be, in the screen that follows. It should be noted that
if another mode is selected in between, that is, either Bar Hole or Monitor, a warm-up period is
necessary when re-entering the Survey or Truck Surveymodes.
Bar Holing: The detector measures gas levels in sampling holes used for locating
underground natural gas resulting from seepage or leaks in a conduit. Gas concentrations in a bar
hole near a significant leak will exceed several percent. Therefore an alarm for gas is likely, but
since it is not relevant to the ambient atmosphere above ground, it is automatically suppressed.
During bar-holing, the alarms for all gases are automatically turned OFF.
To bar hole, select an appropriate probe (see Part 1, Section 7) and set the front panel to
Bar Hole (BH). The instrument automatically clears any residual gas and checks for clean air. The
pump is then turned off and the instrument is ready for bar holing. After inserting the probe into
the bar hole, press the “Go” button. The pump is turned on and the instrument samples gas for a
fixed time (factory set time is 15 seconds). Readings during sampling are shown on the display.
At the end of the fixed time for sampling, the instrument turns off the pump, and displays the peak
and sustained readings. Both values are in % GAS.
If in the course of bar holing, water is encountered, press the left “Stop” button to stop the
pump. Use of a water-stopper (see Figure 2 in Section 8) will prevent water from entering the
instrument.
Monitor: The detector shows the concentration of natural gas (methane) in air in steps of
0.05% GAS (1% LEL) up to 5% GAS (100% LEL) and then in steps of 1% GAS up to 100% GAS.
The concentrations of CO and O2 are also shown if the unit is equipped with the corresponding
sensors (see below). To mute the alarm, press the middle button (mute is displayed). Pressing any
button backlights the display for 20 seconds. To backlight while in the Monitor mode, press the
middle (mute) button twice.
The peak reading for GAS is retained and displayed along with the current readings until
the unit is turned off, another mode of operation (e.g. Survey) is chosen, or a new zero is obtained.
To return from ‘Monitor” to the “Survey” mode, press BH and after the bar holding screen appears,
press Survey. Occasionally, the Survey mode may have to be re-zeroed (press Zero/off and then
Zero) after this transition.

7
The filter provided with the flue probe must be used to avoid interference by
nitrogen oxides in combusted gas. A filter is good for about three months of
ordinary use. It should be replaced or refilled when about 90% of its purple
material has changed color to brown, or when it gets clogged or flooded (see
"Accessories and Spare Parts", Flue Gas Filter, Part No. FF-005 and Purple
Beads and Spare Retaining Disks, Part No. PR-050).
CAUTION:
To Detect Carbon Monoxide
Carbon Monoxide in Ambient Air
Connect an appropriate probe with a water-block filter and select the Monitor mode. After
warm-up, the display shows the concentration of CO in parts per million (ppm). If the air is clean
(contains no carbon monoxide), the display should read zero. If it does not, use the right
“Zero/Off” button to obtain a new zero in clean air.
Carbon Monoxide in Flue Gas
Connect the flue gas probe, with an attached flue gas filter, to the water-block filter on the
hose and select the Monitor mode. After warm-up, insert the probe into the flue and read the
concentration of CO in parts per million. A flue gas check of CO should take one minute or less.
For every minute of flue gas sampling allow the detector a minute of room air sampling to dry the
filters.
Note: The standard flue gas probe and filter are suitable for spot checks lasting a
minute or two. For measurements of CO in flue gas over longer periods use an
Extended Duty Flue Gas Probe and Filter (Part No. FP-012).
“Air-Free” CO Flue Measurements.
The VGA-411/412 detectors can display measurements of CO on an “air-free” basis if this
feature is selected (see Part 2). Where this selection is made, the measured CO concentration is
referred to air-free flue gas according to:
"Air
−
Free"PPM CO
=
20.9
(20.9
−
measured
% 0
2
)
(
measured ppmCO
)
The instrument displays CO concentrations on an air free basis, using the above relation,
up to 16% Oxygen. Beyond this, CO concentrations are displayed without conversion, i.e. the
“air-free” formula is not used.
“Air-free” CO readings shown on the display are labeled AFCO, i.e. Air-Free CO.
WARNING: Do not touch the flue probe immediately after a measurement.
Wait until it cools. Running the instrument in air helps cool the probe.

8
WARNING: The instrument will not operate when first turned on if it fails to block when the air
intake is blocked. Subsequently, however, connections can only be checked by
blocking the probe inlet and observing “Flow Blocked” on the display. If “Flow
Blocked” fails to appear, the probe and/or inlet must be checked for leaks.
CAUTION: Zero adjustment must be carried out in clean air, otherwise a systematic error will be
introduced in subsequent measurements. The instrument will auto zero in concentrations
of methane below 0.10% GAS and concentrations of CO below10 ppm.
4.
INSTRUMENT CHECKS
Automatic Sensor Check
If a gas sensor fails (opens up), the display shows “Replace Methane Sensor”.
Automatic Pump Check
If the intake is blocked, the display shows "Flow Blocked" and the detector beeps untilthe
problem is cleared. This check is carried out whether or not a probe is being used. During the
power on sequence, if a blocked flow is not detected within 40 seconds (from manually blocking
the intake to the pump), the detector displays “No Block Check Probe” then “Remove Probe and
Block Intake”, and finally “Repair Pump”.
Check for Tight Connections
To check for tight connections, block the probe inlet to observe "Flow Blocked" on the
display. If "Flow Blocked" fails to appear, there may be a leak.
Automatic Zero
The zero is adjusted automatically when Zero is chosen from an appropriate display.

9
WARNING: The methane and CO sensors use catalytically active surfaces which may be
poisoned by air contaminants. These sensors should not be exposed to atmospheres
that contain silicones, halogens and halides, such as chlorides, and volatile
compounds containing lead or antimony. If exposure to atmospheres that adversely
affect the sensors is suspected, the detector should be recalibrated promptly.
5.
INTERFERENCE FROM OTHER GASES OR LIQUIDS
The methane detectors use two sensors:
i)
A catalytic combustion filament calibrated with methane. It is used up to aboutthe
lower flammable limit (5.0% by volume) of methane.
ii)
A thermal conductivity sensor calibrated with methane. It is used from the lower
flammable limit (5.0 vol %) to 100 vol % of methane.
Models VGC-301 and VGC-311 (methane and carbon monoxide detectors) use the sensors
listed above and:
iii)
A three-electrode, electrochemical cell for carbon monoxide.
Models VGO-321 and VGO-322 (methane and oxygen detectors) use the methane sensors
listed above and:
iv)
A two-electrode, electrochemical cell for oxygen.
Gases, or liquids with appreciable vapor pressure, which may interfere with the detection
of methane include substances which can be combusted on the catalytic combustion filament
(examples are ethane, propane, ethylene, propylene, octane, and the like) and substances which
differ in thermal conductivity from air (examples are hydrogen, helium, carbon dioxide, other
hydrocarbons).
Gases or vapors which may interfere with carbon monoxide detection include substances
which can be electrochemically oxidized or reduced on the working electrode of the
electrochemical sensor. Examples are hydrogen, hydrogen sulfide, oxides of nitrogen, alcohols,
and unsaturated hydrocarbons.
Many of the substances that interfere with CO are removed by the flue gas filter (Part No.
FF-005). This filter can be used for both flue gas measurements and for ambient air measurements
of CO whenever the ambient concentration of other oxidizable substances is significant.

10
WARNING: The batteries must be changed in an atmosphere known to be non-
hazardous.
WARNING: Do not attempt to charge the alkaline (non-rechargeable) batteries because
they may leak or vent.
WARNING: Use only rechargeable batteries from Bascom-Turner.
WARNING: To reduce the risk of a battery venting, do not mix old batteries with new
batteries, or mix batteries from different manufacturers.
WARNING: Do not attempt to service the instrument in a hazardous atmosphere.
6.
CHANGE OF BATTERIES
Gas-Rover detectors may be powered by two (2) alkaline (non-rechargeable) C-size
batteries (1.5V, Type AM-3) or by two rechargeable nickel metal hydride (NiMH) batteries sold
by Bascom-Turner. The batteries are good for at least eight, and typically ten, hours of continuous
operation. When the batteries are drained to about one hour of remaining continuous use, the unit
alarms and the display flashes "Low Batteries" between readings. If battery life is over, the unit
displays "Low Batteries" and powers down; the batteries must be changed to make the instrument
operational again.
To change batteries:
1.
Turn instrument OFF.
2.
Remove spent batteries.
a)
Unscrew the battery cap and slide out two C-cells.
b)
Discard two alkaline C-cells or recharge the NiMH cells.
3.
Insert two, fresh C-size alkaline batteries or two charged NiMH C-sized cells.
4.
Replace the battery cap and give it one quarter turn (battery cap bar vertical).
Note that the batteries are inserted with the positive terminal first.
If the instrument does not operate after battery replacement, there is a high probability that
a battery has been inserted with the wrong polarity. Re-insert the batteries taking extra care to
insert each battery correctly.
Note: Always replace a set of batteries with a new set. When operating in cold weather (below -
10oC) use a fresh set of batteries, if possible. Alkaline batteries have shortened life in cold
weather; NiMH are recommended.

11
CAUTION: Never attach the flue gas filter cartridge directly to the sample hose - always use
a dust and water-block filter.
WARNING: Hold the probe without touching metal while it is in the flue and immediately
afterwards. Running the instrument in air after a measurement will help
cool the probe quickly and dry the filters.
WARNING: Hold the steel bar hole probe only by the insulated handle to avoid
electrical shock from buried power lines.
7.
PROBES
Surface Probes
A surfaceprobe, 36 inches long, terminating in a rubber cone, is available for above ground
service (Part No. SP-636).
Gooseneck Probe
The gooseneck probe (Part No. GP-514) is a 14 inch long flexible probe which connects to
the dust and water-block filter and a quick connect fitting.
Flue Gas Probe
The flue gas probe (Part No. FP-110) is a telescoping metal probe screwed finger-tight into
the flue gas filter. The other end of the filter attaches to the dust and water-block filter. This
probe, together with its filter, may also be used for CO measurements in ambient air.
Bar Hole Probes
There are five optional probes suitable for bar holing:
Bar Hole/Ceiling Probe (Part No. BP-034) 34" long, clear, one hole at end.
Bar Hole Probe (Part No. BP-134) 34" long, clear, side holes.
Bar Hole Probe (Part No. BP-136) 36” long, fiberglass, one hole at end.
Bar Hole Probe (Part No. BP-236) 36" long, fiberglass, side holes
Bar Hole Probe (Part No. BP-536) 36" long, steel, side holes.
The stainless steel probe has an electrically insulated handle. Bar hole probes are designed
to be attached to the water block filter on the hose. A convenient way to release water from a bar
hole probe is with a water-stopper (Part No. WS-001) described in Section 8.

12
CAUTION: Do not use a Gas-Rover without a dust and water-block filter.
8.
ROUTINE MAINTENANCE
Dust and Water-block Filter
A filter, housed in a knurled nut, removes particles of dust and dirt and blocks water. Do
not insert objects into the water block filter as they may puncture the filter. The filter needs to be
replaced monthly or sooner if it turns brown. Replacement dust and water-block filters are
available as Part No. WF-505 (package of 5 filters).
Figure 1. WF-505.
Inlet Dust Filter
Removal of the intake connector of the instrument (used to attach the sampling system of
choice) exposes a metal filter pressfit onto the intake. These filters are not a substitute for dust
and water-block filters as they will not block water or remove very fine dust and dirt. If this filter
gets blocked, it should be replaced.
Water-stopper
The water-stopper (Figure 2) provides a quick way to continue
bar holing if water is encountered in a bar-hole. The water-stopper is
inserted between the dust and water-block filter and the bar hole probe.
A float inside the water-stopper is connected to a plunger which blocks
flow whenever the float is lifted by water. By depressing a release
push-button, the water is released and the plunger returned to its
normal position.
Figure 2. Water-stopper
Dust-Stopper
The dust-stopper is a filter with a large surface area on which dust can collect without
slowing the sampling rate of the Gas-Rover. The filter element is easily cleaned or replaced by
removing the threaded cap and either blowing off the accumulated debris or pulling the filter off

13
Do not remove or puncture the white filter in the bottom of the filter cartridge.
If this filter becomes damaged, discard the filter cartridge.
CAUTION:
and replacing it. Replacement dust filter cartridges are available as Part No. DF-105. The dust-
stopper should be inserted between the dust and water-block filter and the probe or water-stopper.
Flue Gas Filter
This filter is screwed, finger-tight, between the telescoping metal flue probe and the dust
and water-block filter. It must be used for CO measurements in flue gas and may also be used for
CO measurements in ambient air. The beads in the filter cartridge should be replaced when about
90% of the material has changed color from purple to brown or when it becomes blocked by soot
or water. Filter beads for refilling approximately 50 cartridges are available as Part No. PR-050.
Replacement flue gas filters are available as Part No. FF-005 (package of 5 filters).
To refill the filter cartridge, remove the threaded top and pour out the spent filter material.
Retrieve the plastic retainer disk from the spent filter material. Fill the cartridge with fresh filter
material up to the bottom of threads, place the plastic retainer disk flat on top, and screw the top
finger tight. Check the seal by carrying out a block test with the detector.
Heavy Hydrocarbon Filter
A heavy hydrocarbon filter, filled with activated carbon, can be used with the standard
probe or the bar hole probe on a one-time-only basis. Activated carbon adsorbs gasoline and other
heavy hydrocarbons (for example, propane or butane) which interfere with methane detection. In
order to keep the filter material from adsorbing hydrocarbons prior to use, the filter is fitted with
plastic end caps which must be removed just before use. The filter should be either discarded after
use or refilled with activated carbon and recapped with the plastic end caps. This filter is designed
to be screwed finger-tight between the probe and the dust and water-block filter. Activated carbon
for refilling approximately 50 cartridges is available as Part No. HR-050. The refill procedure is
the same as described for the flue gas filter. Heavy hydrocarbon filters are available as Part No.
HF-005 (package of 5 filters).
The heavy hydrocarbon filter can also remove some alcohols and unsaturated hydrocarbons
which can interfere with CO readings. The filter should be discarded or refilled
after each use.

14
Truck
BH
Survey PPM
In all instances, it is important that the sampling systems be leak tight.
Even slight leaks can compromise the accuracy and response time of a
mobile sampling system.
WARNING:
APPENDIX 1
MAIN SEQUENCES FOR OPERATION MODES
Bar Hole
Surv Go Mon
Truck Survey ∙ PPM
BH (Mute) Surv
CO/O2 %Gas/Peak
BH (Mute) Zero/Off
PPM Tr
BH (Mute) Zero/Off/Surv
APPENDIX 2
THE GAS-ROVER™ IN MOBILE SURVEYS
The Gas-Rover™ can easily be installed in a company’s vehicle if the sampling system
meets Bascom-Turner’s specifications. Vehicles that are currently using a Heath Detecto-Pak III
or IV for mobile surveys need minimal modification. Vehicles using older equipment or
equipment from other manufacturers, such as Dafrol or Southern Cross, need a more extensive
modification. For new vehicles, Bascom-Turner has available a mobile survey kit (Part No. MP-
001) which can be installed in about 4 hours.
MODIFICATIONS OF EXISTING SAMPLING SYSTEMS
The two chain and funnel assemblies that run from the front bumper should be about four
feet apart and centered. Adjust the funnel height to one inch above ground. Connect a flow meter
capable of displaying flows from 0 to 5 LPM (Dwyer RMA-26 or equivalent) to the tubing that
connects the pump to the instrument. Turn the adjustment knob on the outlet side of the pump to
read 3 LPM. Remove the flowmeter and connect the Rover to the outlet of the pump using the
special connector supplied by Bascom-Turner (Part No. MA-024). When using the Rover in a
mobile fashion, the unit must be set in the Truck mode.
MODIFICATIONS FOR OLDER SYSTEMS
Problems with older systems may be inadequate secondary pump volume and multiple
funnel assemblies. The funnel assemblies should be reworked to only two funnels set one inch
above ground. The secondary pump must be replaced with a larger pump supplied by Bascom-
Turner (Part No. HP-001).

15
PART 2. SETUP AND CALIBRATION
1.
SETUP
Setup Time and Date. To change the time and/or date of a Gas-Rover, power the unit
with the left “Power-On” button and when the unit displays the time and date, press the right “Edit”
button once. The first digit of the hour will begin to flash. The right “Update” button will
increment the flashing digit and the left “Next” button will advance it. When Next is pressed at
the last flashing digit, the Edit screen is restored and the power-on sequence resumes with the
edited time and date.
To review or change other setup parameters, power on the Gas-Rover with the left “Power-
On” button and while the unit displays “Bascom-Turner Gas-Rover” press the right button once.
A menu of three parameters will be displayed with a pointer to the right of the first parameter:
Alarm Limits
Bar Hole Time
Air Free CO
Power Off
The left “Yes” button selects the parameter indicated by the pointer while the right “No”
button advances the pointer to the next parameter.
Once a parameter is selected the current setting can be saved unchanged by pressing the
left “Save” button or can be changed by pressing the right “Edit” button. If editing is selected, the
Edit screen flashes the parameter or portion of the parameter which can be toggled or incremented
with the right “Update” button. When a (flashing) parameter is OK, press the left “Next” button
to either advance to the next digit or to leave the Edit screen and display the edited parameter.
Alarm Limits. Alarm level displays which allow limits to be saved or edited are:
%LEL
Alarm Limit: 1 to 20%
Factory Setting: 20%
%GAS
Alarm Limit: 0.1 to 1%
Factory Setting: 1%
SURVEY PPM
Alarm Limit: 5 to 500 ppm
Factory Setting: 10ppm
PPM CO
Alarm Limit: 1 to 200ppm
Factory Setting: 35ppm
The low and high percent oxygen alarm limits (19.5% and 23%) can not be changed.
Bar-Hole Time. The bar-hole time is the time, in seconds, during which gas is sampled
from a bar-hole. The peak and the average of the last three readings are stored and displayed. The
bar-hole time can be set from 5 to 60 seconds. The factory setting is 15 seconds.
Air-Free CO. Gas-Rover detectors with both CO and Oxygen sensors may be setup to
display CO on an “air-free” basis. This choice may be appropriate when sampling flue Gas which
may contain varying amounts of “excess” air. When this feature is enabled, the instrument
automatically calculates the concentration of CO in ppm in a gas free of Oxygen and displays it in
the Monitor mode labeled as AFCO. Whenever the amount of Oxygen in the sampled gas exceeds
16%, CO is automatically reported without the excess air correction, i.e. as measured, on the
assumption that the medium is in fact air and not flue gas. This feature is set at the factory at OFF,
i.e. disabled.
This manual suits for next models
9
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