Does anyone know the procedure to calibrate the Omega HH506RA thermometer? I will use boiling water as a reference. The instruction manual is about the poorest thing I have ever seen.

Omega, they're called "technical writers", do your part to help the economy and hire one.

Typically with these meters you would go into the menu & select Offset, then enter the + or - setting for that input to correct the reading.

Joel -

I have this thermometer and have successfully re-calibrated it a few times. I recall that it is a PITA, and cannot be done "closed case" like the Flukes can.

You need to open the case and short a couple of pins on the PCB together. Then you will need both an accurate 70mV source, and an accurate 0.0*C source.

The 0.0*C source could be a reference thermocouple in an ice slurry, or a thermocouple calibrator, or a special purpose ice point instrument.

How far out of calibration do you think it is? My experience has been that mine holds calibration quite well.

Jim

Jim,

I think is fairly close, although as I was trying to read my data, I mistakenly put it into a mode that seemed like a calibration setting where I could not escape without an input.

I was planning to calibrate it to boiling water temperature just in case. Sounds like the offset feature is a lot easier than doing the proper calibration procedure. Just a shame they can't write a decent manual for it.

Also, I've calculated the boiling point of water as 203.5 F at my house, based on 5000 foot elevation and barametric pressure correction factor of 0.5F for 30.2" Hg. This is from the tables that EricS posted: http://www.hi-tm.com/Documents/Calib-boil.html. I thought that barometric pressure was the only factor in determining boiling point, but this reference suggests elevation and barometric are required. Is this correct?

Joel

JBSmoovee wrote:... I mistakenly put it into a mode that seemed like a calibration setting where I could not escape without an input.

Been there. Not proud of this, but I've jerked the battery out of the thing more than once to "get its attention" when it was locked into some weird mode

JBSmoovee wrote:I was planning to calibrate it to boiling water temperature just in case. Sounds like the offset feature is a lot easier than doing the proper calibration procedure. Just a shame they can't write a decent manual for it.

The manual is pretty bad.

Measuring the temp of boiling water to within fractions of a degree can be tricky. There is a fair amount of variation in the water due to convection currents. I've found it best to loosely place a sheet of aluminum foil over boiling distilled water, then measure the temperature of the steam pocket that is between the foil and the water surface. Take care not to seal the foil tightly because you do not want to generate any pressure.

I'm sure you're also aware that BP is dependent upon barometric pressure, so an adjustment needs to be made for local elevation and barometer readings.

A slurry ice bath is a much easier thing to build and measure as a reference point, but isn't as close to the temperatures you are likely to care about measuring.

Jim

JBSmoovee wrote:I thought that barometric pressure was the only factor in determining boiling point, but this reference suggests elevation and barometric are required. Is this correct?

Sorta. Depends on your definition of barometric pressure.

The BP only depends on the absolute pressure, and doesn't care a bit about elevation above MSL, just like you said. So if you have some means of measuring absolute pressure, then that is all you need.

Generally you will have to rely instead on a local weather station to provide you with barometric pressure. Trouble is, they always reference their reading to sea level. So if you are using weather station info, you must add the additional elevation correction to "undo" the adjustment made by NWS to provide you with a sea level referenced value.

If this makes no sense to you, then you are among friends

Jim

PS - if I have any of this wrong, I'm confident that EricS will tactfully correct it

Generally you will have to rely instead on a local weather station to provide you with barometric pressure. Trouble is, they always reference their reading to sea level. So if you are using weather station info, you must add the additional elevation correction to "undo" the adjustment made by NWS to provide you with a sea level referenced value.

Ah, now those NOAA barometric pressure readings make sense. I couldn't figure out why my barometric pressure was so close to MSL!

I have a cheap barometer on order, so it'll be interesting to see how that compares to the NOAA data.

All this work just to get some brewing temperatures!!!

Yea, right

Go to the FTP site below my sig and I have a nice MS Excel file on condensation temps. This is the way I do thermometers and I feel good about it.

The thermometer sensors are immersed in a bed of steam of distilled water.

I have one of those Suunto watches with an altimeter. In addition to being a great gizmo for mountain hiking, its barometer readings gave me helpful information when I did what you are doing. In fact, I got better measured vs calculated BP agreement using the unadjusted watch barometer reading than from using weather station data.

The weather station data was from 10 miles away, and always lagged behind a little. Plus, I only know my elevation to within around +/- 40 ft, so that also introduces some error.

Jim

In addition, see the posts on Page Nine of this: Scace Thermofilter Temperature Device