Overall the recovery (over a month) should be more than 95% of the Helium given to your laboratory. Then all joints, seals and valves are tested by a “Helium leak-detector” in its “Sniffer mode”. ![]() To know whether a recovery line is good for Helium or not – the line has to be pressurized to approximately 5 atmospheres. So some seals which may be leak tight for Nitrogen are not necessarily “leak-tight” for Helium. Helium gas can diffuse through the pores of many materials even when other gases cannot, because the Helium molecules are smaller in size. Hydrogen exists mostly as H2 molecule which is larger in FAQ : Liquid Helium Plant : November 2018 P a g e | 3 size than this. Remember that Helium atom is the smallest “freely floating” atom with a size of 30 picometer (approx.). Q: What do you mean by a “good and efficient” recovery system?Ī: A good and efficient recovery system must be “Helium leak-tight” to a leak rate of 1e4 mbar-lt/sec. If you want to carry the same amount in gaseous form, you would require at least 10 standard cylinders (gas stored at 150 atmosphere pressure), with each cylinder weighing more than 50 kgs! So bringing “some gas” in cylinders is not at all an easy proposition! In fact 100 litres of liquid can be carried in a container whose tare weight may not exceed 100 kgs. So this will work only for very large volumes of gas which have to be carried in very heavy cylinders, under pressure. So in general, this will have too many potential problems that can cause difficulties with regular operation. There is a danger of impure gas contaminating our stock. This means that unless we are 100% sure about the purity of the gas that you have brought we cannot allow this. The gas that you have brought in general will require to be mixed with our pool of gas. A small amount of gas cannot be liquefied in isolation. Q: If I bring some Helium gas in a cylinder, can you liquefy it for me?Ī: This is not as simple as it sounds. The actual production by the liquefier is about 20% more since a certain amount goes into precooling the dewars during every transfer into smaller dewars. So the lost amount was 5.06% of the amount given to users. This fraction should be as low as possible.įor example In the period OCT 2017 – SEPT 2018 we disbursed 14,463 liters of liquid to ten different systems. Then take how much fresh (pure) gas we had to put in to keep the circulation going. ![]() Q: How do you calculate the losses and quantify this?Ī: We take the amount of liquid given out during the whole year. More accurately it is 750 liters or 0.75 cu mt. Q: How much gas is really needed to produce one liter of liquid?Ī: 1 liter of liquid Helium weighs 125 gms (0.125 kg) = 31 moles = 31 x 22.4 = 694.4 liter at NTP (approx). If users do not return books (Helium loss) or return them in badly damaged state (contaminate the gas) then the library will not be able to sustain itself! ![]() Please treat Helium from the facility like a library book. The cost of liquefaction itself is a lot less than the cost of the gas. Since we recover ~95% of the gas and re-liquefy the recovered gas, the cost comes down enormously – because the same volume of gas gets recirculated many times. Thus without recovery, the cost of 100 liters of Helium would be close to 80,000 Rs. It is 800-1000 Rs/liter at current rates. In fact if you buy liquid Helium from industrial suppliers you will find that the cost of 1 liter of liquid is largely the cost of the equivalent amount of pure gas. Q: Why can’t you just give me some Helium in a dewar?Ī: The cost of liquid Helium is largely (~80%) the cost of the pure gas. Please note that we cannot give Helium to laboratories without a proper recovery system and flowmeter tested by us. Q: What do I need to do to get Helium from the facility?Ī: You need a clean and leak proof helium recovery system or a thoroughly checked return gas line from your laboratory to the helium plant. FREQUENTLY ASKED QUESTIONS ABOUT LIQUID HELIUM PLANT:
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