CF and Wire Seal Flanges & Fittings
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The Vacu-Shield cold trap is capable of working with two different cooling agents. For high vacuum application, liquid nitrogen is the preferred agent and provides better trapping results. At low vacuum levels or during system pump down, a dry-ice and alcohol mixture can be used. The trap is electropolished inside and out, has cap handles, and has a vented stopper all included standard. The VSCI traps have an in-line port design for installation and a simple 2-piece clamped body design to ease trap cleaning.
A third port is included on all LN2 traps except the 0.8 liter trap. This third port is intended to serve as a vacuum break or vent. Without some means to break vacuum on this line, the liquid nitrogen Dewar will be difficult to disassemble for cleaning or servicing. Under no circumstances should a screwdriver or similar tool be used to separate the liquid nitrogen Dewar from its stainless steel, vacuum jacketed housing. The most common configuration for this port is to include a tee with the appropriate ISO-QF terminations. On one side of the tee an up-to-air valve is attached and, on the other side of the tee, a vacuum gauge (typically a thermocouple or Pirani) is attached. The up-to-air valve allows the system to be safely vented and the vacuum gauge provides an additional check on the trap's base pressure to ensure vacuum integrity. Note: If a separate up-to-air is not employed or the vent port is sealed ("blanked off") during use, some means of venting or breaking vacuum must be included in the inlet or outlet pumping lines.