As a LN2 food freezing engineer for Airco Industrial Gas out of Murray Hill NJ (1968?) I was temporarily tasked with investigating a claim from a liquid helium customer that we were shorting them on their half full orders of 100 liter dewars of liquid. It didn't take long to figure out the customer was right because our NJ distributor was filling the tank by weight. And the headspace density of saturated gas was just about as much as the liquid so indeed they were paying for mostly vapor which is not nearly as useful to them as liquid. A full (by weight) tank could be about half full of vapor. I advised them to stop trying to sell partly filled liquid helium dewars. i was subsequently reassigned to food freezing projects.
Spending lot of He for nothing.... Just before pitting transfer line to the Dewar u have to close exhaust and check valve. After that slowly put trans line to Dewar. That case pressure inside will grow up a bit and it will be about recommended 3psi. Measuring level in tank is not very useful task, but u spending lot of He for that. Check weight of Dewar before and after, but better to trust LHe level meter. I am an engineer for NMR spectrometers and have installed dozens of them. Weighing is a reliable way to determine the amount of liquid helium in a vessel. Much more accurate than using a deep stik. The less you open the vessel to the atmosphere, the less loss.
As a LN2 food freezing engineer for Airco Industrial Gas out of Murray Hill NJ (1968?) I was temporarily tasked with investigating a claim from a liquid helium customer that we were shorting them on their half full orders of 100 liter dewars of liquid. It didn't take long to figure out the customer was right because our NJ distributor was filling the tank by weight. And the headspace density of saturated gas was just about as much as the liquid so indeed they were paying for mostly vapor which is not nearly as useful to them as liquid. A full (by weight) tank could be about half full of vapor. I advised them to stop trying to sell partly filled liquid helium dewars. i was subsequently reassigned to food freezing projects.
Thank you for this video!
Spending lot of He for nothing.... Just before pitting transfer line to the Dewar u have to close exhaust and check valve. After that slowly put trans line to Dewar. That case pressure inside will grow up a bit and it will be about recommended 3psi. Measuring level in tank is not very useful task, but u spending lot of He for that. Check weight of Dewar before and after, but better to trust LHe level meter.
I am an engineer for NMR spectrometers and have installed dozens of them. Weighing is a reliable way to determine the amount of liquid helium in a vessel. Much more accurate than using a deep stik. The less you open the vessel to the atmosphere, the less loss.