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Nitrogen purity requirments

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Nitrogen purity requirments | 29 June, 2006

We have an ERSA Versaflow Ecoselect selective wave soldering machine. It works well except it needs nitrogen. You can't even move the table around if your nitrogen tank is empty.

The spec sheet says Required degree of purity: Nitrogen liquid 5.0 Purity 99,999 Vol.%

So far we are just using good ol' eutectic solder not lead free in it.

Do we really need to have the nitrogen at 99.999%? I would think 99.5% would do the job but would not want to buy a generating system and then find there is a noticable deterioration of the joint quality.

Does anyone know how expensive nitrogen generating systems are? I've submitted one RFQ so far.

Even if you don't use them the liquid nitrogen tanks only last a week or so.

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Nitrogen purity requirments | 29 June, 2006

I might be wrong since I don't know this piece of equipment but I think ROL might be a better measure. For 63/37 it used to be 20 ppm ROL (residual oxygen level) was about what you needed for a reflow oven. This is to take full advantage of all that nitrogen had to offer. So you would measure the oxygen ppm, in your application, with an oxygen meter.

Sounds like you are operating off a tank or more correctly a dewar. A dewar is a tank with an evaporator inside. The nitrogen is liquid and changes to a gas as it passes through the evaporator. The evaporator converts the liquid nitrogen to gas. I assume you know why the tank (dewar) goes empty even if no nitrogen is used. If not, I will explain. As the liquid nitrogen changes to as gas, this happens as the nitrogen warms, pressure builds up and the dewar must vent the excess pressure. This venting consumes liquid nitrogen.

I will bet you are paying a lot more for delivery of nitrogen dewars than you would if you had a bulk storage tank. You probably could reduce nitrogen cost if you went bulk. However, your bulk tank will vent just like the dewar will. This is why it is important to size your bulk tank to your consumption of nitrogen. If you don't use the nitrogen, the tank will vent the nitrogen.



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Nitrogen purity requirments | 30 June, 2006

I looked into nitrogen generators, it was 4 years back and I was trying to get 99.995 i think. About �20,000 for the generator then another �20,000 for the compressor you need to force the air in. I spoke with David Groome of BOC UK 01709 842358

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Nitrogen purity requirments | 30 June, 2006

The manufacterer of our machine recommends 99.999%. At their presentation before we purchased the machine they showed an example of using different purity levels. When they whiched the supply to 99.99 and then to 99.95 you can visibly see the difference in the quality of the miniwave. They also had some studies of the joints themselves and you can see internal oxides when poorer N2 is used.

For our production, we haven't tried other N2 purity levels.

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two cents


Nitrogen purity requirments | 4 July, 2006

100 PPM or 99.99% purity is sufficient for any soldering application. There are a number of manufacturers that make PSA style nitrogen generators that are great systems for electronics applications. They are low maintenance and will pay for themselves in 12 to 14 months. If you are considering a bulk tank, there are expenses there as well....tank rental....concrete pad...real estate...If you are only going to inert a single machine or a few systems, you will not have tremendous rates of consumption thus you will not need a huge compressor to run them. Are you running more than one shift?....Nitrogen generators must be sized to meet peak demands. They pay for themselves quicker if you run multiple shifts. The only maintenance costs for a system the size you would need will be the filters which will cost about $300 to $400 annually. Most Companies have shop air that kicks out a standard 110 to 120 PSI. If you have capacity on an in-house generator, you might have the air to meet the system requirements. It is well worth looking into as the price of Nitrogen varies greatly. If you are interested in learning more...send me an e-mail or reply.


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