A customer recently asked me about installing a UPS (Uninterpretable Power Supply) on his bench-top mass spectrometer system. Here's how I went about explaining how and why.
How to backup the power to your GCMS system.
In order to specify a UPS, you need to know the following characteristics of your system: Voltage, Amps and Hours (you want to run if the power goes off). The easy part is the volts, its 120 volt for most US systems. I would recommend a backup of 30-60 minutes .... lets say one hour to keep it simple. In order to determine how many amps you need to protect, you have to look at each electric device. There's always a electric name plate on each device (or there is supposed to be) which will specify the amounts of amps the device "draws". Add up all the amps and then multiply by 1.2 or 1.5 (as a safety factor) and you have the amps needed.
Then multiply Volts x Amps x Hours and you will have the UPS rating needed to "back up" your system.
Unfortunately if you go through this process, then attempt to find a suitable UPS you will find that the UPS you need to buy is about the size of an Igloo Cooler and costs $4k to $5k.
Then he asked me "Can't I just back up the mass spec ?"
Backing up only the mass spectrometer explained:
Here's how I answered him: If the PC loses power, the run stops and you lose the data. You have to re-run the sample. If the GC loses power, the run stops and you lose the data. You have to re-run the sample. If the Mass Spec loses power, the run stops and you lose the data. You have to re-run the sample. If the VACUUM (rough) PUMP loses power, the run stops .... you lose the data..... and the mass spec is ruined. The mass spec is ruined due to a massive and catastrophic "back stream", the topic of another Tech Blog later.
So, the most important item to UPS is the Vacuum Rough Pump. You may lose the data, but the mass spec (diff pump or turbo pump) has a chance to cool down and "shut down" safely. A much better choice.
