Submerge temperature sensors in liquid hydrogen (LH2)

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.

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

For LH2 measurement, Si-diodes like DT-470, Band 11, or DT-670, Band A seem suitable. While your product catalog offers temperature probes, they're too short for a 1.25m distance to the liquid. Immersing Si-diodes in the SD package directly into the liquid hydrogen may pose challenges like temporary ban material compatibility and insulation. Consider consulting with a specialist for specific advice on this setup.







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