Model 921A Combustible Gas Meter
Model 921A Combustible Gas Meter
Measure total combustible gases (TCG) in oil-filled transformer nitrogen gas blankets with this rugged, portable instrument.
The Arbiter Systems®, Inc. Model 921A Combustible Gas Meter is a rugged, portable instrument that measures total combustible gases (TCG) in oil-filled transformer nitrogen gas blankets. TCG measurements have been shown to be good indicators of transformer health.
The supplied cylinders of Instrument Air, Zero Grade Nitrogen and 1% Methane in Nitrogen calibration gases support field calibration, after which TCG measurements are virtually automatic.
The Model 921A also has a built-in gas pressure sensor. By connecting the gas sampling hose to the PSI port and pressing PSI, the blanket fill gas pressure can be accurately measured.
The Model 921A is provided with a hard-sided transit case, along with instrument air, nitrogen, and 1% calibration gas cylinders and all necessary regulators and accessories.
- Measures total combustible gases (TCG) in the field
- Includes cylinders of Instrument Air, Zero Grade Nitrogen and 1% Methane in Nitrogen calibration gases
- Built-in gas pressure sensor
- Includes regulators and accessories.
Input
TCG
| Inlet Pressure | 1 to 5 PSIG, nominal |
| Damage Inlet | Vacuum to 30 PSIG |
| Gas Inlet | Female Luer Fitting |
Pressure
| Damage Limit | Vacuum to 30 PSIG |
| Gas Inlet | Female Luer Fitting |
Air
| Purity | Zero-Grade Instrument Air, 21.00% Oxygen |
| Inlet Pressure | 20 to 25 PSIG or use supplied regulator |
| Air Inlet | Female Luer Fitting |
Measurements
TCG
| Range | 0 to 10.0% |
| Accuracy | ±(5% of reading + 1 count) |
| Resolution | 0.01% TCG |
| Calibration | 1% Methane = 1% TCG |
Sensitivity to Various Gases
(reading for 1% gas in nitrogen, typical)
| Methane | 1.00 |
| Carbon Monoxide | 0.48 |
| Hydrogen | 0.86 |
| Acetylene | 1.9 to 2.0 Note: Interactions between the catalyst and acetylene cause the sensitivity to gradually increase during a sequence of acetylene measurements. This does not affect the sensitivity to other gases, and the effect is reversed on standing. |
| Ethylene | 1.92 |
| Ethane | 1.64 |
| Air (100%) | -0.07 Note: The thermal conductivity of air, being slightly higher than that of nitrogen, will cause a negative reading by virtue of differences in thermal conductivity. While not optimized as a thermal-conductivity detector, this is an indication that transformer gas is not reaching the Model 921A. |
Pressure
| Range | 0 to 15 PSIG |
| Accuracy | 0.1 PSI |
Interface
Operator
| Display | 16 character alpha-numeric supertwist LCD |
Power Requirements
Internal Battery
| Type | Gelled-electrolyte lead-acid, 6 V / 4 AH |
| Operation | 400 measurements on full charge |
| Charging Time | 8 hours typical |
General
Physical
| Instrument/Size | 130 x 230 x 65 mm (5.125 x 9.125 x 2.625 in.) |
| Transit Case | 400 H x 380 W x 240 D mm (16 x 15 x 9.5 in.) |
| Shipping | 533 x 533 x 533 mm (21 x 21 x 21 in.), container |
| Weight | 3 kg (7 lbs), net (instrument) |
Environmental
| Temperature | Operating: 0 °C to +50 °C |
There are no additional Options for this product
| Included | |
|---|---|
| AP0001800 | Plug-in charger, 120 Vac UL/CSA |
| AP0002500 | Automobile lighter adapter |
| AS0019100 | Calibration Gas Regulator Individual Calibration Gas Regulator. Two are included with purchase of Model 921A.
|
| AS0019300 | Transformer gas hose assembly |
| AS0019402 | Calibration gas hose assembly (red) |
| AS0019406 | Calibration gas hose assembly (blue) |
| AS0019500 | Calibration Gas - Instrument Air |
| AS0019600 | Calibration Gas - Zero Nitrogen |
| AS0019700 | Calibration Gas - 1% Methane in Nitrogen |
| FT0001200 1 | Particulate Filter (ea) |
| PD0010700 | Operation Manual (921) |
| Available | |
| AS0019501 | Calibration Gas - Instrument Air - Case of 12 |
| AS0019601 | Calibration Gas - Zero Nitrogen - Case of 12 |
| AS0019701 | Calibration Gas - 1% Methane in Nitrogen - Case of 12 |
| AS0020500 | Syringe Adapter (Kit of 5 each) |
| AS0020800 | Bag of 10 Particulate Filters (FT0001200) Ten(10) particulate filters (individual part number is FT0001200)
|
| AS0026900 | Transformer Hose In-Line Filter Kit |
| AS0026901 | Transformer Hose In-Line Filter Kit - Bag of Five |
| AS0035100 | Annual Filter Maintenance Kit |
1 Two filters are included
TCG Measurement Comparison
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Model 921A combustible Gas Meter Filter Replacement Instructions
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Methane In Nitrogen (MSDS)
Download PDF(136 kB) »
Nitrogen (MSDS)
Download PDF(130.5 kB) »
Oxygen in Nitrogen Mixture (MSDS)
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