Water boiling point

TRANSPLANTED HILLBILLY · Fri Jan 20, 2006 3:05 pm

After finishing a run it was late and didn't get cleaned up for a couple days. After filling my boiler with water and firing it to clean I happened to notice the head temp at the 1st sign of steam, 193.8 deg. F. I thought that's odd so I kept watching, steady climb just like a regular run. It hit 198.0 deg.F and held steady for 45min. till I shut er down. I watched steam continue to exit till the temp hit 195.7 and then stopped.

Now when I got into this hobby I checked my water boiling point several times on the stove top with all of the thermometers I have. I found it to be 198 every time I checked it. I'm at 8250 ft elevation.

They are all digital and from the same MFG., measure both C & F, and are all within .2 degF of being same. And I check them fairly regular against each other just to verify I'm not losing a battery. So the thermometer is accurate.

I have well water so there shouldn't be any thing in there with a lower boiling point.

My question is, did the steam begin early because of low vapor pressure in the coil, (3/8" dia. x 15 ft.) or is it because of the lag time involved to heat up the column. The column is 2" stainless 18" tall.

I have done this a couple times before but never turn on the thermometer. Just really curious whats going on here. Has anybody else seen this, or is it normal?

linw · Post by **linw** » Sat Jan 21, 2006 2:54 am

8250ft is very high = lower air pressure = lower boiling point.

Post by **Grayson_Stewart** » Sat Jan 21, 2006 6:36 am

Started at 193.8F then climbed to your regular water boiling temp of 198F right? What was the time span of the climb from 193.8 to 198? Couple of minutes, couple of hours? This is a pot still or a column with scrubbers? No spent wash in the boiler, only water?

TRANSPLANTED HILLBILLY · Sat Jan 21, 2006 9:51 am

Yeah linw, I know that.

Grason this is a pot still. There would have been residual wash but nothing forming a pool. No scrubbers.

The increase in temp actually took less than 15 min. and I ran it for another 30 min.

As I am typing this reply I see where your going. The residual washmay not be much as soon as I drain but the stuff that clings to the walls of the boiler/column/worm, has probably totaled up to enough to lower the boiling point for that short period of time.

Is that in fact where your going or did I miss the bus. Make sense to me I hope I'm right.

Post by **Grayson_Stewart** » Sat Jan 21, 2006 10:04 am

Thats the only thing I could come up with.

TRANSPLANTED HILLBILLY · Sat Jan 21, 2006 10:08 am

Thanks for kick startin' my brain. It works pretty good most times but experiences gear lock at other times.