Is Agilent overselling filaments on purpose?
When I first entered the analytical instruments industry, I was thrown into it full-on with literally no knowledge of what kind of tools scientists used for their experiments. Growing up on cartoon science labs and Frankenstein’s Monster, you don’t really get a true picture of a modern lab really is.
I graduated from “take these machines apart and put the parts that look like each other in piles” to being the go-to person for refurbishing anything from an old 3393A HP integrator to Agilent 1100 LCs. It was all a really exciting couple of years.
One thing that came from this time was the thought process that ‘Agilent always wanted to sell consumables’, which is why they asked that both filaments be changed each time the source was cleaned (or during a PM, at the very least).
Years later I had the fortune of working for Agilent and was officially trained on their GCMS. During that training, I had the opportunity to challenge this thought process. What I learned was eye-opening.
When an electron is sent from a filament across the repeller to the opposing filament, it does not stop there. It has the opportunity to bounce back and forth between the repellers up to 8 times. Read that again!
So, during this time, the unused repelled is being blasted by all those electrons, weakening it. Even as it sits unused.
This is not to say everyone should replace both filaments at each PM. But this information should give you a better understanding of why it is a good practice to do so.