Okay, as I'm bringing my standards lab instruments on line, my other issue is tightening temp controls in there. Anyone pretty well versed in temp controls for labs. I know the right (expensive) methods. What are some methods to reduces about thirty minute sawtooth (2 deg C peak to peak = ~+/-1 Deg C) in my temp? I am taking five minute intervals with a Temp/RH datalogger. I plotted on Excel. I know some of the common sense answers as my senior tech and I discussed it ad nauseum this morning. We need to improve insulation. But we don't have a "laboratory" HVAC system. Until funds are available for that - hopefully pretty soon; I wanted to think of some low $$ stop gaps to tighten up the temp. the RH spikes in a trend with the Temp, but I believe smoothing out the Temp will by definition, smooth out the RH.
We'll end up hiring an HVAC consultant; but I thought I'd see if anyone had any thoughts or ideas. This is part of bringing my electrical standards lab online.
I may invest in one of those plexiglas dryboxes and put things in there to dampen fluctuations - but that seems crazy to have to do.
I'll stop there to see if anyone has general ideas.
QuoteI may invest in one of those plexiglas dryboxes and put things in there to dampen fluctuations
I've always found that putting your Temp/RH datalogger in one of those does help their stability tremendously.
:-D :lol: :-D :lol: :-D :lol:
Unless you are planning on calibrating inside your plexiglass box all you are doing is creating the illusion that you have an environment.
You missed the :-D :lol: :-D :lol: :-D :lol: didn't you.
If you don't have a real HVAC system to work with you're pretty much fighting a losing battle. If it comes to innovation then you will have to take a look at what equipment you have powered on (adding heat). Also consider controlling the number of people who are allowed in your calibration area. You can probably get an infrared thermometer to check the temperature of the air coming out of your ceiling ducts to possibly determine if there is a stuck valve or some other problem in a particular area. Good Luck.
I think in actuality what I'll have to do is not have "cookbook" environmental controls (i.e.: standard lab specs), but walk through all of my measurements.
One of the stop-gaps I want to do is remove the duct feeds from that room. It's on the same thermostat zone as the main lab. If I move those feeds out of there, it will average the same as the main lab (open doorway between the two), but maybe not have the same sawtooth caused by them (some sawtooth, but not quite so bad). It also runs a little too cold in there. So by removing the AC duct feeds, that might also warm it up.
I bought new T/RH dataloggers, so I no have good MS Excel plots of just how the sawtooth looks. I think my most critical application is upcoming resistance cals with the 9975 (my biggest concern). My Thomas 1 Ohm standard has its own air bath. I may have to put the RTD in, and plot a series of readings to estimate how much the Temp fluctuations add to uncertainty, and de-rate my uncertainty in those readings; then use that (compared to what the uncertainty would be with more stable environment) as some of my ammunition to get them to pay for environmental control upgrades.