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| Oxygen Analyzer
for Welding Stainless Steels |
|
| The Model SGI-3 is an oxygen
analyzer for monitoring the residual oxygen of purge and shield gases used in
the welding of stainless steels The SGI-3 has upgraded digital electronics and replaces the popular SGI-2 instrument. |
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Features of the SGI-3
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Introduction to the SGI-2, SGI-3 measurement system Inert gas welding requires the exclusion of oxygen from the weld
zone during the welding process. The shield gas ( typically argon ) needs to be
free of oxygen from air leaks into the feed hose and the back side of the weld
needs to be protected with a purge, or backing,
 gas to
ensure a low or controlled oxygen concentration on the back face of the weld.
On the front face of a weld the the inert gas stream (provided it is free of
leaks ) efficiently excludes oxygen from the weld zone. On the back side of the
weld special precautions must be taken to prevent oxidation. This involves the
isolation of the back side of the weld with fixtures that provide for the purging of this area
with an inert atmosphere. The SGI-3 instrument works with these fixtures to
continuously sample the purge gas and to monitor the oxygen concentration.
Monitoring the weld gases with an SGI-3 adds a quantifiable element of quality
control to the inert gas welding process. It also provides an economic benefit
by giving the welder the information he needs to accurately judge the purge gas
flow rate and purge period. ( The SGI-3 is the latest version of
the SGI-2 analyzer)
Principle of Operation of the SGI-3 Weld gas analyzerThe SGI-3 contains a small pump which draws a continuous sample from the purge gas in the welding zone. This sample is passed into a special zirconium detector that is very sensitive to the presence of oxygen. A zirconium sensor is an electrochemical oxygen concentration cell with a solid ceramic electrolyte. It has the property of producing a small emf (voltage) in the presence of oxygen. The relationship between the emf produced by the detector and the oxygen concentration is well understood and highly repeatable. This means that the detector can be calibrated directly in oxygen concentration units. Sensors of this type can be used to measure concentrations from a few ppm all the way up to 100% oxygen. They are very reliable, the calibration is stable over long periods (years) and a detector calibrated for use with low ppm concentration as in the welding application will not saturate or show any degradation when exposed to high oxygen concentrations (air for example). |
| Sensor Type | Ceramic / Zirconium detector |
| Measuring Range Argon | 5000 ppm to 1 ppm oxygen in argon |
| Measuring range Fourmier | 500 ppm to 10 ppm |
| Accuracy | Better than +/- 1% FSD |
| Display | LED bar across front panel |
| External output | 4 - 20 mA |
| Dimensions | 225 x 250 x 180 mm |
| Weight | 6 kg |
| Model No. | Description | Order on line Price US$ |
| SGI-3 (replaces the SGI-2) |
Complete instrument includes: Controller with LED readout, built in sample pump, 10 ft. of connecting hose, filter and reusable shipping carring case. Calibration certificate for one year | $4400.00 |
| SGI2-GAP | 1.6 mm diameter stainless steel probe for inserting into gaps to monitor oxygen, in back of the weld, through the gap. | $135.00 |
| Item | Description / Part No | Price US$ |
 |
External Filter 920002 |
$75.00 |
 |
Internal Filter 92003 |
$55.00 |
| 5 mm OD 3 mm ID by 10 meters long | Oxygen Impervious Hose 910596 |
$30.00 |
 |
Compression Nut 940006 10 pack |
$20.00 |
 |
Bulkhead fitting 890362 10 pack |
$95.00 |
 |
Metric M5 to hose fitting 890360 10 pack |
$35.00 |
| Straight fitting 960596 10 pack |
$65.00 |
Topac Inc. 231 CJC Highway, Suite 103 Cohasset MA 02025 USA
Tel:
781 740 8778 Fax: 781 740 8779
| E mail |
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