Summary of Contents for BT CGA-411
- Page 1 BASCOM-TURNER INSTRUMENTS GAS-SENTRY® DETECTORS OPERATION MANUAL GAS-SENTRY DETECTORS CGA-411 AND CGA-412 COMBINED METHANE, CARBON MONOXIDE/ HYDROGEN SULFIDE, AND OXYGEN DETECTORS Part Number OM-0100...
- Page 2 LIMITED WARRANTY Bascom-Turner Instruments warrants Gas-Sentry Detectors to be free from defects in materials and workmanship for one year following the date of shipment. Sensors are warranted for three years and the electronics for five years following the date of shipment.
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Page 3: Table Of Contents
TABLE OF CONTENTS PART 1. OPERATION Features The Gas-Sentry CGA-411 and CGA-412 Detectors ..........Specifications ......................Operation ......................... Enclosed Spaces, Leak Detection, Bar Holing, Ambient Air and Flue Gas Testing for CO ........................Interference from Other Gases or Liquids ............... -
Page 4: Part 1. Operation
PART 1. OPERATION FEATURES The Gas-Sentry® portable, combined methane, carbon monoxide/hydrogen sulfide, and oxygen detectors are intrinsically safe, microprocessor based instruments designed to test ambient air over a wide temperature range. These detectors have many features for easy and reliable operation: •... -
Page 5: The Gas-Sentry Cga-411 And Cga-412 Detectors
* test for carbon monoxide and hydrogen sulfide in ambient air * test for carbon monoxide in flue gas and other gases given off by appliances Displays for the CGA-411 and CGA-412 detectors are selected by a front panel switch. They include:... -
Page 6: Specifications
Steps of 1% from 4 to 100% Power Supply Four AA Alkaline % LEL 0 to 100% (Model CGA-411) (1.5V Type AM-3) or PPM CO 0 to 9999 ppm carbon monoxide in steps of 1 ppm Four AA Ni/Cd Rechargeable... -
Page 7: Operation
OPERATION Overview of Essential Operating Practice Gas-Sentry detectors are easy to use. However, a few general rules must be followed to insure reliability and accuracy. Pump. Gas-Sentry 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 first turned on. - Page 8 A detector can be tested with "bump" gas. Such tests only verify that the gas sensor(s) are in operating condition; to adjust their sensitivity they must be calibrated. A detector can be automatically calibrated in less than one minute using Bascom-Turner's calibration gas (2.5% methane and 100 ppm CO in air).
- Page 9 * The % GAS display spans the whole range of methane (0 to 100%) with the following sensitivities: Readings from 0 to 4.0% Steps of 0.05% Readings from 4.0 to 100% - Steps of 1.0% To Display Carbon Monoxide with the "PPM CO" Display. Connect an appropriate probe to the dust and water-block filter and set the selector switch to "PPM CO".
- Page 10 If the alarm for a display (% GAS or PPM CO) is turned off, alarms for other detected gases (CO and oxygen in the case of % GAS, and natural gas and oxygen in the case of PPM CO) will still be given if these gases exceed their alarm limits. However, the alarm frequency is reduced (once every 15 seconds) to minimize interference with readings.
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Page 11: Enclosed Spaces, Leak Detection, Bar Holing, Ambient Air And Flue Gas Testing For Co
ENCLOSED SPACES, LEAK DETECTION, BAR HOLING, AMBIENT AIR AND FLUE GAS TESTING FOR CO Test and Monitor an Enclosed Space Atmosphere The CGA-411 and CGA-412 detectors may be used to test and to monitor an enclosed space atmosphere. WARNING: The detectors respond to natural gas (methane), carbon monoxide, hydrogen sulfide, and oxygen. - Page 12 The display will show "Snif" (sniff) for about 10 seconds. After this initial warm-up, the display shows the concentration of methane (natural gas) in air in % LEL (Model CGA-411) or in % GAS (Model CGA-412). If ambient air is clean (contains no methane), the display should read zero.
- Page 13 A general guide on the adverse effects of CO at various concentrations is given in Table 3. A concentration above 35 ppm in breathable air is cause for concern. The time-weighted limit (8 hr.) for CO in the workplace is 50 ppm and the short-term (15 min.) limit is 200 ppm. The effect of higher concentrations becomes more severe with increasing exposure time.
- Page 14 S will register as 200 on the PPM CO display and 100 ppm H will register as 400 on the PPM CO display. The CGA-411 and CGA-412 detectors thus monitor ambient levels of hydrogen sulfide, as well as CO, and will alarm if the H S concentration rises above one quarter of the limit set for the CO alarm.
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Page 15: Interference From Other Gases Or Liquids
INTERFERENCE FROM OTHER GASES OR LIQUIDS Methane detection uses a catalytic combustion filament and a thermal conductivity sensor, both calibrated with methane. The filament is used up to about the lower flammable limit (5.0% by volume) of methane and the thermal conductivity sensor from about 5% to 100% of methane. -
Page 16: Instrument Checks
INSTRUMENT CHECKS Pump Checks If the intake is blocked, the display shows "bloc" (block) and the detector beeps until the problem is cleared. This check is carried out whether or not a probe is being used. To check for tight connections, block the probe inlet to sow "bloc" on the display within a few seconds. If "bloc"... - Page 17 Coarse Zero To adjust the zero of a sensor which has drifted too far, remove the instrument from its carryall, and remove the elongated rubber plug on the right side of the instrument (as you face it) to access two push-button switches. Place the instrument on a flat surface and set the selector switch at the % oxygen display.
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Page 18: Change Of Batteries
CHANGE OF BATTERIES Automatic Battery Check The Gas-Sentry CGA-411 and CGA-412 can be powered by four (4) alkaline (non- rechargeable) AA batteries (1.5V, Type AM-3) or by four (4) Ni/Cd rechargeable batteries (1.25V, 0.85 Ah). If the estimated battery life is less than about 1 hour, the display flashes "Lo"... -
Page 19: Troubleshooting
TROUBLESHOOTING Problem Probable Cause Action 1. Display is blank and pump • Batteries are too low or • Replace batteries (see does not operate. spent. Section ("Change Batteries"). 2. Batteries are replaced but • One or more batteries were • Re-insert batteries with display is blank and pump... -
Page 20: Probes And Filters
PROBES AND FILTERS Standard Probe The standard probe (Part No. SP-207) is a rigid tube which connects to the water-block filter. If extra length is desired, an extension (7") is screwed finger-tight onto the end of the probe. A rubber gas collector (Part No. RT-107) on the end of the extension is useful for finding leaks under windy conditions. - Page 21 electrically insulated handle. Bar hole probes are designed to be attached to the water block filter on the coiled hose. A more convenient hose for bar hole measurements, five feet of straight tubing, is available as Part No. SH-060. CAUTION: Hold the steel bar hole probe only by the insulated handle to avoid electrical shock from buried power lines.
- Page 22 Dust Filter for Gooseneck Probe A dust filter in the tip of the gooseneck probe can be cleaned by removing the probe from the detector and tapping the probe's tip on a hard surface to remove dry dust and dirt. The dust filter can be popped off the end of the probe and replaced.
- Page 23 Water-stopper The water-stopper (Fig. 6) is a floating check-valve, with push-button water release, to stop water from being pumped while bar-holing. It provides a quick way to continue bar-holing if water is encountered in a bar-hole. The water stopper is inserted between the water-block and dust filter and the bar-hole probe.
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Page 24: Part 2. Calibration And Alarm Level Selection
PART 2. CALIBRATION AND ALARM LEVEL SELECTION AUTOMATIC CALIBRATION WITH A-CAL™ ™ ™ ™ The A-CAL firmware calibrates instruments automatically using calibration gas available from Bascom-Turner Calibration Gas. The gas required for automatic calibration of the catalytic combustion and CO sensors is Bascom-Turner's methane and CO calibration gas (Part No. MC-105) containing 2.5±0.05% methane and 100 ppm ±2 ppm CO in air. - Page 25 The detector display will show "GAS 2" while the catalytic combustion sensor is being re-calibrated and "CO" when the CO sensor is being re-calibrated. After calibration, the detector will show "CAL" and the instrument will beep briefly. Remove the probe from the gas outlet. The instrument is ready for use. Note: When the Gas Dispenser is used, it may be useful to attach the 7"...
- Page 26 Disconnect the probe from the gas and let the instrument run briefly in clean air to purge residual gas. Monitor the purging by placing the selector switch on the GAS scale. When the reading on this scale returns to zero, the instrument is ready for use.
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Page 27: Alarm Level Selection. "Air-Free" Co Option Selection
ALARM LEVEL SELECTION. "AIR-FREE" CO OPTION SELECTION The instrument has an alarm activated at preset levels. Factory set alarm limits are given in Section 3C. The TRACK GAS scale has both an alarm and a beeper which may be disabled without disabling the alarm. - Page 28 SniF display (see below). SniF followed by a number The TRACK GAS alarm is at value shown. If ON, displayed number is % LEL (CGA-411) or or by OFF The TRACK GAS alarm is OFF. % GAS (CGA-412). Maximum setting is 20% LEL or 1.00% GAS.
- Page 29 To Change Alarm Levels. If an alarm level is to be changed, rather than turned OFF, select the relevant display by pressing switch #2 an appropriate number of times, then press switch #1 until ON appears, then press switch #2. The display will show a number (the previous alarm level) with a flashing first digit.
- Page 30 To Change the Alarm Level for the CO Display to 35 PPM CO. Set the front panel switch to AUTO ZERO and press switch #2 five times. The display will advance to CO followed by a number (the current alarm level). Continue by Press Display Comment...
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Page 31: Manual Calibration, Sensor Replacement, Pump Adjustment
MANUAL CALIBRATION, SENSOR REPLACEMENT, PUMP ADJUSTMENT Manual calibration is required if a sensor has drifted too far to be calibrated automatically and sometimes when a sensor is replaced. Since the procedures described below accesses basic operating parameters, safeguards have been built to ensure that the set-up mode is not entered accidentally. - Page 32 For manual calibration or installing a new CO/H S Cell (Sects. 12A and 12B) GAS 3 followed by a number Not used for CGA-411/412 Not used followed by 9999 Not used in the field May be used when installing a new oxygen cell.
- Page 33 Methane Sensor Replacement The Bascom-Turner methane sensor is housed in a sintered metal flame arrestor and is connected to the board by a short length of cable terminating in a 6-pin connector. A hold-down plate, used to secure the methane sensor to the gas manifold, is captive on the cable. The tools required for replacement of a methane sensor are a Phillips #1 screwdriver and a small implement wide enough to reach both push button switches on the right side of the instrument.
- Page 34 Remove four screws from the aluminum block manifold freeing the sensor hold- down plate and cable strap, and lift the methane sensor out of its well. Verify that an O-ring remains positioned on the shelf at the top of the well. Install the new sensor assembly and press down until it sits in the well with its cable aligned directly toward the 6 pin connector on the main circuit board.
- Page 35 If "nogo" appears on the display during AUTO ZERO, use the coarse zero procedure described in Section 6. If "nogo" appears during automatic calibration, calibrate manually as described in Section 12A. Replace the two rubber plugs on the side of the instrument. Replacement of the CO/H S Sensor The CO/H...
- Page 36 Note: Do not press down in the center of the corrosive warning label on the CO sensor as this may damage the electrical connection to the sensor. Fig. 9. Intake manifold assembly and connectors inside a detector. Reconnect all connectors on the bottom of the board (see Fig. 9). Make sure each connector has the proper orientation.
- Page 37 Replacement of the Oxygen Sensor The oxygen cell should not be opened since it contains a corrosive electrolyte. The old cell should be returned to Bascom-Turner for proper disposal. Please use the container furnished with the replacement cell for the return. The tool required for replacement is a Phillips #1 screwdriver.
- Page 38 Adjustment of the Block Limit of the Pump If a "bloc" signal is not displayed when the air intake to the instrument is blocked, the problem may be corrected by adjusting the block limit used to detect this condition. Before any adjustments are attempted, determine that the absence of a block signal is not due to a leak in either the probe, the hose, or some connection along the way.
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Page 39: Set Up And Purge Of The Calibration Dispenser
APPENDIX I SET UP AND PURGE OF THE CALIBRATION GAS DISPENSER Calibration Gas. The gas required for automatic calibration of the catalytic combustion and CO sensors is Bascom-Turner's methane calibration gas (Part No. MC-105) containing 2.5 ±0.05% methane and 100 ppm ±2 ppm CO in air. It is provided in a disposable aluminum tank containing 105 liters of gas, sufficient for at least 300 calibrations. - Page 40 Attach the regulator to the cylinder and tighten the CGA connection nut (i.e., turn the tank clockwise while holding the regulator). Verify that the regulator's valve is closed. Secure gas cylinder to a wall, bench or stand with the mounting bracket (Part No. MB-001) so it will not tip over or fall.
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Page 41: Set Up For Manual Calibration
APPENDIX II SET UP OF THE MANUAL CALIBRATION APPARATUS These instructions should be followed when setting up and using the manual calibration apparatus (Part No. PCA-001). The components of the manual calibration apparatus are shown assembled in Figure 11, they include: Description Part Number Methane gas dispenser... - Page 42 REGULATOR AND HOSE INSTALLATION Secure gas cylinder to a wall, bench or stand with the mounting bracket (Part No. MB-001) so it will not tip over or fall. Be sure both the regulator and cylinder have compatible CGA fittings. Do not attempt to use an adapter to connect incompatible CGA fittings.
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Page 43: Accessories And Spare Parts
Inlet Filter & Threaded Air Intake (5/pkg) ..............Inlet Filter & Quick Connect Air Intake (5/pkg) ............Sensors Methane Sensor (for CGA-411 & CGA-412) ............... Carbon Monoxide Sensor (for CGA-401,411, and 412) ..........Oxygen Sensor (for CGA-401, 411 and 412) ..............