LESER carried out in-house functional tests under real conditions to prove the correct functioning of spring loaded and pilot operated safety valves under cryogenic medium conditions.
For the functional test LESER developed a new test concept consisting of a 1000 l Cryo-Cylinder filled with liquid nitrogen at -196°C (-320°F). The test pressures were supported by superposition with gaseous nitrogen.
On a newly designed test table, the valves were hydraulically clamped on a specially developed adapter.
To generate the cryogenic test conditions, the safety valve inlet (closed state of the safety valve) was continuously flushed with liquid nitrogen at -196°C (-320°F).
After complete cooling to <-162°C at the inlet, the functional tests were carried out.
The safety valves were tested with >3 opening cycles at a set pressure of 16 bar with liquid nitrogen still present at the inlet.
Various spring-loaded safety valves of type 526 in nominal sizes DN25 x DN50 (1"x2") and DN50 x DN80 (2"x3") and pilot-controlled safety valves in nominal size DN25xDN50 (1x2) were tested under cryogenic medium conditions.

The results obtained corresponded to the expected functional behaviour. Even after repeated testing, a perfect opening and closing function was achieved. This means that there were no functional limitations due to temperature influences on the components, such as the spindle and spindle guide. A sign that these temperature conditions have already been taken into account in the development and design.
This result proves once again that LESER safety valves work safely and flawlessly even under difficult operating conditions, such as cryogenic media.
A further milestone to give the customer the necessary assurance that LESER products are the right choice.
In addition to this extended functional test, LESER has been operating a specially developed test bench for safety valves for measuring the tightness with helium under cryogenic conditions on the basis of ISO 13648-1 for quite some time.