Date: Tue, 20 Dec 2022 03:44:27 +0000
I would like to thank everyone who took the time to read and respond to my emails.
Dwyer may still make special flow meters for helium flow measurement.
Due to the low volume of sales, they don't put them on their website. Need to contact them on the phone or send them an email to inquire.
custserv_at_dwyermail.com<mailto:custserv_at_dwyermail.com>
tech_at_dwyermail.com<mailto:tech_at_dwyermail.com>
The flow meter for air can also be used for helium. Simply multiply the displayed flow rate by 2.69 to get the flow rate of helium.
For those interested in this topic, I'm including all the emails I've received.
The sender’s name has been removed per AMMRL policy.
Weixing Zhang
Department of Structural Biology
St. Jude Children’s Research Hospital
Memphis, TN 38105
weixing.zhang_at_stjude.org<mailto:weixing.zhang_at_stjude.org>
(901)595-3169
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My helium flow meter on 800
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You try calling them on the phone? They might have them but with so low volume of sales they don't put them on their website.
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you can buy them from Dwyer. The part number is 168063-00. (Special Series VFA Flowmeter). However, we found that their flow measuring is too low for our 700 MHz magnet. It always maxes out. Nevertheless, it tells us whether there is flow at all. Even though it is a special production, we did not find the prices too outrageous.
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Contact Dwyer directly
custserv_at_dwyermail.com<mailto:custserv_at_dwyermail.com>
They can even customizer helium flow meters for you, the service I received before.
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I had to contact them directly and give them the part number. They had them half a year ago.
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In the past, I contacted tech_at_dwyermail.com<mailto:tech_at_dwyermail.com> and they helped me to order the custom design of their flowmeters. Particularly I asked them to make a flowmeter to monitor the nitrogen boil-off rate of my magnets.
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We use the Dwyer VFA flowmeters for air, and multiply the displayed flow rate by 2.69 to get the flow rate of helium.
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I believe that those helium boiloff meters have been manufactured by Dwyer as OEM products “to specification” - worthwhile contacting them, maybe they are willing to make you a couple of these.
I actually may have some of these - got to check after Xmas (currently traveling). Which range of boiloff rate would you need?
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Sorry if this is a dumb question but wouldn’t any gas/air flow meter work? Does it have to be “helium” specific for some reason?
i.e. the meter you found for “air” doesn’t work?
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Just a caveat. We found a lot of leaks around similar flow meters to the one in your picture. In fact we are thinking of removing all the flow meters and seeing if we recover more helium… As you will be installing new, maybe leaks won’t be so much of a problem. Ours are all on old oxford magnets.
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We used omega for the larger volume flow meters (air, but we put tape over the numbers to convert to Helium) when doing fills through them. They also have the smaller ones for boiloff too. Our website has the part numbers for almost everything we used for helium recovery, but we did not buy the small ones for boiloff we just reused the ones from the Varian systems.
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In the FW Dwyer catalog, they tell you how to convert the readings (designed for air) to gases of other densities. So my old group routinely used Dwyer rotameters (intended for air) for measuring helium.
The force on the "float ball" is prop to (1/2) density times velocity-squared. The cross section area between the glass or plastic tube and the ball varies (gets bigger as the ball climbs in the tapered tube).
So at a given ball height (a given reading of the gauge), the force (1/2)
density times velocity-squared is the same (negligible buoyancy
forces). If the density of helium at
NTP is about 1/7 the density of air, the velocity must be sqrt(7) times as large. So the volumetric flow must also be sqrt(7) times as large.
Please check to see if my argument agrees with the Dwyer catalog!
In practice, I always checked this by flowing helium through the gauge and then thru a U-tube immersed in a water bucket. I captured the helium bubbles in an inverted graduated beaker or cylinder. I measured the time to collect 100 mL of bubbles.
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Call Dwyer and ask. They have it.
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I'm sure Dwyer would sell you some, if you contact them directly. They're just standard flowmeters with a different custom scale that both Bruker and Varian bought for their instruments. Our Varian 600 came with one that goes up to maybe 150 cc/hour, not that the magnet normally boils off anywhere near that much, but there could probably be scenarios where a big magnet would peg the meters that only go up to 50 cc/hr. I assume these are not intended for a pumped magnet--I would shy away from introducing anything into the flow path that could act as a constriction on the flow.
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See page 245 of the Dwyer flow catalog for conversion of readings on a gauge calibrated for one gas to another. He specific gravity is 0.137.
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I placed an order for three of these flow meters earlier this month and just received them yesterday. They came from a Canadian Distributor for Dwyer. They had a difficult time finding the right product - it appears to be a special order.
I can send you the info when I get back into the office on Monday. The fact that I’m in Canada and dealing with a Canadian Distributor may not be as useful for you but perhaps it’s worth a shot.
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I had a quick look at Dwyer's page. I think this is where you'd look https://dwyer-inst.com/products/flow/flowmeters/variable-area/series-vf-visi-floatr-acrylic-flowmeter.html<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdwyer-inst.com%2Fproducts%2Fflow%2Fflowmeters%2Fvariable-area%2Fseries-vf-visi-floatr-acrylic-flowmeter.html&data=05%7C01%7CWeixing.Zhang%40stjude.org%7C43f47f3171a44d5a7d0d08dae02f781a%7C22340fa892264871b677d3b3e377af72%7C0%7C0%7C638068791890088511%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=6qZSkNGtC2CovQEVvuhmtJJABak6AAn6pYosO0fedOk%3D&reserved=0>. You may already have and I didn't see the He flow meter there.
The Bruker part number is below. I believe it's a "special" OEM part which would explain why you can't find it at Dwyer. You would need to contact your Bruker sales rep for a quote.
He flow meter: B790791 (Flow gauge Dwyer 0-50 cc/hr)
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Call Dwyer and ask. These gages will certainly register a value, the question is can Dwyer give you an accurate scale for Helium or a conversion.
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One can order from Dwyer but it's proprietary and you will need Brukers permission. On Monday, I may be able to find my order. for these that includes the part number.
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I don't know where to buy it. However, if you cannot find where to buy, we have a few in stock. I need to check with sales about price. It should be within a couple of hundreds.
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Are you just using this to measure boiloff during normal operations? or during fill?
We found that the Helium level flow meters for normal boil off do not have sufficient range and so we just used one for air and then there is a ~ 2.4x factor to correct for actual boil off.
I think you don’t need to know the exact level so much as there is boil off and if it changes significantly.
You need something much bigger for your fills.
From: AMMRL List <ammrlrev_at_webserver2.chem.hawaii.edu<mailto:ammrlrev_at_webserver2.chem.hawaii.edu>>
Sent: Friday, December 16, 2022 12:16 PM
To: ammrl_at_ammrl.org<mailto:ammrl_at_ammrl.org>
Cc: Xia, Youlin <Youlin.Xia_at_STJUDE.ORG<mailto:Youlin.Xia_at_STJUDE.ORG>>
Subject: AMMRL: Flow Meter for Liquid Helium
Caution: External Sender. Do not open unless you know the content is safe.
Dear All,
We are planning to install a flow meter on each magnet for our helium recovery system.
Bruker provided a flow meter on some low field magnets, but no such flow meters are provided on high field magnets.
I searched the Dywer website. I can only find flow meters for air and water applications, but I could not find the flow meter for helium.
If you know a place to buy this kind of flow meters, you information is greatly appreciated!
Thank you in advance!
Weixing
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