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Monday, June 20, 2011

#11 - Portable Hydrogen and Oxygen Analysis – Part 1

The Nova Model 340 Portable Hydrogen and Oxygen Analyzer is useful for many heat treating applications. Some of these are considered below.

Copper Annealing


One of the first applications of the 340WP analyzer is for copper annealing. In this case, an atmosphere of 1 or 2% hydrogen is necessary to be sure that oxygen is not present. It’s also necessary that the hydrogen be kept low as high hydrogen will embrittle the copper.

The presence of a leak or oxygen getting into the furnace is detected by a low hydrogen reading. Oxygen itself cannot be detected after it has leaked into the furnace; it is consumed by the surface of copper and discolors it. The air leak is instead found by the low hydrogen reading. Experience has shown that at times the oxygen does not unite with the hydrogen and is still present. This is the reason the oxygen reading is necessary for complete analysis.

Copper Brazing

The 340WP analyzer is very useful for measuring atmospheres in a copper-brazing furnace. These atmospheres must be high in hydrogen in order to eliminate scaling and discoloration, as well as to ensure the proper fluxing of the solder.

In this case, the analyzer can be used both to measure the setting of the gas generator as well as for probing in various zones of the brazing operation. This ensures a proper atmosphere as well as aids in finding problems in atmospheres that are causing discoloration to the work.

Brass Melting

Figure 1 shows a standard type of brass melting pot. These measurements also apply to kiln melting but the older brass melting pot is shown as an illustration. In this case, the gas burner is placed at the bottom of the pot and the flame circulates up around the pot and over the top of the molten brass. The protective atmosphere to reduce the dross is produced by the flame itself. An experienced operator would look at the flame coming out of the furnace and thereby judge the amount of hydrogen in the atmosphere.

Figure 1 - Oxygen & Hydrogen Analysis in Brass Melting Operation

In practice however, even an experienced technician cannot tell whether it is 1% or 6% hydrogen. The hydrogen in this case is very important because if it gets too high it causes not only embrittlement but also produces voids in the castings. Here an analysis taken right inside the flame over the pot is what is necessary. Nova has quartz probes available for this measurement.

The Nova Model 340 Portable Hydrogen and Oxygen Analyzer is available with the following choice of ranges:

0-25.0% O2, 0-40.0% H2
0-2.0% and 0-25.0% O2, 0-40.0% H2
0-100 to 0-9,999 PPM O2, 0-40% H2

Which range is best for you depends on the application. Before purchasing a hydrogen analyser, we require that you tell us what other gases are in your sample. This will determine equipment suitability and design.

Model 340 brochure...

We make gas analyzers for oxygen, hydrogen, carbon monoxide, carbon dioxide, methane, and many other atmospheric gases. We provide gas analysers for syngas, landfill gas, purity gas, biogas, and others.


Give Mike or Dave at Nova a call, or send us an e-mail.
1-800-295-3771
sales at nova-gas dot com
websales at nova-gas dot com
http://www.nova-gas.com/

1 comment:

  1. Hi Dave,

    I think that you should add some information to the blog about low-range CO measurement for fire detection in landfill gas analysis.

    Grant.

    ReplyDelete