The Myth of NIST Traceability for Calibration Gases in Disposable Cylinders- Part Two of Four

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C10 valves were not invented by aliens, but they should have been.

Here's an alien idea- if you want true NIST traceability for a calibration gas in a disposable cylinder (don't believe the hype- there really isn't any for true NIST traceability for mixtures in disposable cylinders- see  Part One in this series of posts)- why would you put it in a cylinder with a valve/regulator combo that immediately destroys the integrity of the calibration gas?

C10 valves and NIST traceable gas mixtures hate each other.

The problem is the C10 valve/regulator combo.  It was never designed for a calibration gas package.  Think I'm kidding?  Not only were the cylinders in use for calibration gases in disposable cylinders designed for the application, the valves weren't either!  That's why you should laugh at any vendor claiming true NIST traceability for the calibration gases in disposable cylinders.  They pretend they're traceable (the McCalgas vendors do this all the time) by throwing in weight numbers not even used to make the mix in the disposable cylinder itself- they were used for another cylinder which was then transfilled into that and a ton of other disposable cylinders which destroys an traceability they might have had.

But, back to the point- C10 valve/regulator combos let room air back into your calibration mix.  This is why for a while some instrument companies recommended using regulators with no control knobs.  It helps a little, but I'm designing a C10 regulator with a serious bleed/purge valve built in.  Who wants the humidity from room air mixing with their calgas?

The Dirty Secret- Push Button Valves Are For Dummies

Think about it- when you screw that regulator in, the gas shoots up from your disposable cylinder and- surprise- the room air inside your C10 regulator is now part of your gas mixture.

Unless you use the Ideal Valve, which prevents the moisture-laden (humidity) air trapped in the regulator from back-flushing into the calibration gas in the disposable cylinder.  More on that next installment.