MULTIPLE TRANSFER LINES (MTL)

While all liquid gases require sophisticated infrastructures, there is one liquid gas with extra challenging characteristics: liquid helium. In addition to being the cryogenic liquid with the industry’s lowest temperature (-268.9 °C), liquid helium is exceptionally scarce and expensive.

To ensure that as little liquid helium as possible is lost while using the gas in an application, Multiple Transfer Lines (MTL) are utilized.

An MTL is one vacuum line featuring several process lines. One or more of these lines transport liquid helium from a storage tank or liquefier (through a valve box) to the application.

After use, the helium warms up, which creates gaseous helium. This gas is then routed back through one process line (again via a valve box) towards the liquefier, with two possible objectives:

• The gaseous helium is liquefied again through a liquefier so it can be reused. In this way, the costly liquid is optimally preserved.
• The inner pipeline containing gaseous helium (approximately -250 °C) is used to effectively cool a copper radiation shield around the process lines.

Since the helium is reused within the system, the MTL, valve box, and liquefier combination is known as a closed-loop system.