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Post by henrikb on Mar 8, 2022 4:05:51 GMT -5
Dear Lakeshore-Team and community,
I would like to ask you to support me in the selection of sensor technology for a LH2 measurement.
For a test bench the temperature of liquid hydrogen should be determined.
For this purpose, Si-diodes, such as DT-470, Band 11 or DT-670, Band A offer the appropriate working range.
In your product catalog are temperature probes, which according to the description are the right product for my application. However, these are clearly too short. The distance from the cover flange of the cryostat to the liquid is 1.25m. Using a submerged cable would be more easy to fit than a probing rod.
Is it possible to immerse Si-diodes in the SD package directly into the liquid hydrogen?
What problems would you expect with such a setup? What needs to be taken care of?
I hope you can give me some advice.
Mit besten Grüßen / with best regards
Henrik
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Post by Lake Shore Jeff M on Mar 8, 2022 13:21:09 GMT -5
Henrik,
According to the applicable North American Standard governing the specification of devices for use in Explosive Atmospheres (IEC 60079-0 7th Edition) and specific to devices governed by the Intrinsic Safety Standard (IEC 60079-11), the Devices Specified by Lake Shore are in compliance with the “Simple Apparatus” Clause 5.7 of IEC 60079-11 7th Edition, under Spark and Thermal Ignition Compliance. It is the responsibility of the User to ensure that the system design follows the integration, operation and maintenance for Lake Shore’s system/sensor components in compliance with the standards of an Intrinsically Safe Circuit and maintains the use of Lake Shore product within the applications designed safety limits.
Lake Shore does not certify or test our products for use in explosive environments or classify them as intrinsically safe. The definition above only states the wattage or our device at specific temperatures and compares it to the NEC code for your evaluation.
With the above said, the main issue with submerging sensors directly into Liquid Hydrogen is that the hydrogen eventually eats away the insulation on the wiring eventually causing shorts or other issues. We have seen issues even when the sensors are in probes as the small molecules can seep into the probe through the Stainless steel tubes which again can eventually cause the sensor or its wiring to fail.
Let us know if you have more questions.
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Post by henrikb on Mar 9, 2022 4:50:46 GMT -5
Hello Jeff,
thanks for your explanation. I'll do some research and will evaluate my options to separate the temperature sensors and their wires from the LH2.
I'll reach back if needed.
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delsipee
New Member
work at the Von Karman Institute for Fluid Dynamics
Posts: 1
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Post by delsipee on Jan 26, 2024 2:24:07 GMT -5
Hello,
I'm Mathieu Delsipée, working at the Von Karman Institute for Fluid Dynamics. We're also considering to use DT-670-SB immersed into Liquid Hydrogen. Tonight we'll discuss with someone from NASA who apparently did it.
At the beginning, we wanted to encapsulate the diode sensor in a copper jacket but then the response time is to high to measure our phenomena.
Do you have any update on how to protect the wires?
Other question : I'm concerned about the outgassing of the wires when we'll do the vacuum in the tank before filling it with Hydrogen. Do you have any experience with this? Do you know which particles are present in the outgassing?
Thanks a lot.
Kind regards,
Mathieu
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Post by Lake Shore Jeff M on Jan 26, 2024 13:04:23 GMT -5
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Post by cbrooks on Sept 17, 2024 17:45:40 GMT -5
Hi there,
We are looking to use the DT-670 with liquid nitrogen. Are there any concerns with cryogenically submerging the SD package in general? Or were the LH2's corrosivity and reactivity the only concerns earlier? We also are very space limited, if we can do without a temperature probe or further sheathing, it would be beneficial.
Thanks so much,
Cooper
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