I've been working as a Manager with a new company at a small forgotten plant (I often say we're the forgotten step-child) within the company for almost two months now. And I discovered, to my horror, the other day that the glass reference thermometer that they have been using to do in-house calibration verification hasn't been actually NIST calibrated since the 80's. So, since the glass thermometer that we do have is in degrees C and we use both C and F in the plant I've started on a journey of glass - which corporate recommends - vs. the digital Aquatuff that I have a fondness for.
Does anybody know if there is a preference among SQF/USDA/FDA/etc. for one over the other? This is assuming that if I were to get a new glass one it would be in F and I would get it and the glass C thermometer both calibrated yearly, while if I were to get a digital it would suffice for both F and C and would be the only thermometer calibrated yearly.