Not exactly, but very close. Here’s what to expect:

Temperature stability:

  • ±1°C variation (normal)
  • -196°C at fill
  • Gradually drifts to -190°C over 6-8 weeks as liquid nitrogen evaporates
  • After refill, returns to -196°C

Why the drift? When liquid nitrogen evaporates:

  • Gaseous nitrogen (top of dewar) is -160°C to -180°C
  • This colder gas (above liquid) insulates the liquid slightly less
  • The liquid slowly warms as the level drops

Important note: Even at -190°C, samples remain perfectly viable. The critical threshold is about -150°C, so you have a large safety margin.