Lamp ignitions and lifetime

We have a lot of 1260s and 1290s in our lab, and as part of our sustainability initiatives are looking for ways to reduce our energy usage.  Currently, all the instruments are left on (standby), and most of them also have the lamps on when not in use.  We are considering turning off the stack or just the lamps in between uses.  One concern is that repeatedly turning the lamp on and off also reduces the lamp lifetime.  Is there a recommended balance between leaving the lamp on to reduce ignitions, and turning off after use to reduce energy usage?

  • And if we have decided that our usage is infrequent enough to turn the lamp off, would it also make sense to turn the power off to the whole instrument?  We do make sure to flush the lines first and leave them in 20% methanol. 

  • Will be interesting to see the answers to this one!
  • I'm interested in this also - I currently have our systems on all the time (just in standby mode if not in use) lamps are just switched off overnight/weekends at the end of a sequence. If the degasser is constantly turned off could this possibly cause issues? (is it best to leave degasser on unless shutting down for an extended shutdown period?). 

  • Sure, repeated ignitions mean stress for the lamp, but if a lamp gets ignited two or three times a day, that's perfectly fine. I would switch off the lamp, if the instrument is not used for 3-4 hours. However, it depends a lot on the type of detector and the peaks you're interested in. If you only check the highest peak, you might not be interested so much in baseline stability, but if you're looking for traces of contamination, baseline stability is vital. Therefore, for the latter, I would leave the lamp on during two sequences. The VWD needs some time to stabilize, but a DAD, especially the sensitive G4212X/G7117X with their Max-Light Cartridges take much longer. On an RID, everything is about stability, so I would not turn off anything, unless the detector goes back to the shelf. An FLD is the complete opposite. On most FLD applications the lamp can even be switched off during an injection (e.g. the last peak of interest came out after 25 minutes, but the run time is 50 mins).

  • Okay, thanks for the info.  Sounds like we have been overly cautious about turning the lamp off in between uses.  

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