Page 1 of 1

Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 3:55 pm
by lsayre
Every once in awhile I check the zero on my Dwyer 25 manometer, and occasionally I find that the zeroing dial needs to be cranked in (clockwise) a bit to bring it back to reading zero. I figure that at some juncture I'll run out of in-travel on the zeroing dial. It appears to me that the oil is evaporating over time. Can this be correct, or is something else going on here? Will it eventually get to where I need to add additional oil?

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 5:15 pm
by Freddy
lsayre wrote:Will it eventually get to where I need to add additional oil?
I experience the same thing.... every year or two I have to add some oil....not much, but some. It's going someplace! Evaporation? Leaks through the tubing like air from tires? A neighbor takes some with a Q-tip to oil his rifle? I don't know, but it does go someplace. Now.... each time I have purchased a new Dwrey 25 it has come with a bottle of oil. After filling there is always some left over, enough at least to top it off for a few years. You can buy just the oil from Dwyer, but it's not cheap....mostly because of shipping.

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 5:44 pm
by lsayre
I wonder how many people are looking at their Dwyer manometer and wondering why they have lower than normal draft for this time of year, when the real problem is that some of the oil has evaporated and they are thereby getting a false low reading, whereby they simply need to disconnect and dial in a new zero?

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 5:57 pm
by Lightning
I calibrate mine weekly at minimum just by pulling the brake line out of the pipe and checking for zero. Over the summer I did notice the reading fell a bit and had to recalibrate it at start up this year.

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 5:58 pm
by Wiz
lsayre funny you mention oil evaporating. Yesterday my draft showed -.05 while stoker was on idle, I thought wtf is going on. No big deal I'll just zero it back in, that's when I realized that dial was already max clockwise. :notsure:

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 7:19 pm
by McGiever
Dwyer Magnehelic use no oil, so never an oil issue with them. ;)

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 9:35 pm
by Keepaeyeonit
:yes: McGiver you are so right,
IMG_2405.JPG
.JPG | 126.9KB | IMG_2405.JPG
but when I had a #25 I found the oil seeped out the threads on the plastic knob and I would have the same problem but not no more :D .Keepaeyeonit

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 9:38 pm
by lsayre
Nice! What are the other two monitors in the picture tracking?

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 9:46 pm
by Keepaeyeonit
Middle one is the flue gas temp between the stove and baro,and the lower is the black pipe temp at the clay liners.If the lower one works good then I will replace the middle one with the same unit but with a different thermocouple.

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 9:53 pm
by lsayre
Is your Magnehelic a Model 2000-00N?

Re: Does Manometer Oil Evaporate?

Posted: Sat. Oct. 26, 2013 11:02 pm
by Keepaeyeonit
No I think it's #2000-00 not #2000-00N.

Re: Does Manometer Oil Evaporate?

Posted: Sun. Oct. 27, 2013 1:19 am
by SMITTY
Just realized a couple weeks ago these damn things do indeed have evaporating oil ... so that tells me it's not really "oil" ... but anyway ....

Be carefull adding the stuff. I put less than half an oz in there .. and I went from not being able to zero it in the negative, to not being able to zero it less than .04"! Figures ... Now I have to do math every time I look at the damn thing ... :x :lol:

Re: Does Manometer Oil Evaporate?

Posted: Sun. Oct. 27, 2013 5:32 am
by lsayre
Every liquid has a "vapor pressure" so indeed every liquid evaporates at some rate if left open (and the manometer is open to the air on one side and to the flue on the other). Oil evaporates extremely slower than water, but eventually it does evaporate. This being a very thin and light oil, it probably evaporates much faster than a heavy oil.

Re: Does Manometer Oil Evaporate?

Posted: Thu. Nov. 07, 2013 7:03 am
by Dennis
after 4 years my oil had evaporated to nothing on the scale,then of course I over filled it and had to syphon some out,(boy that red oil tastes like crap) and then had a vaccum block after that.After letting it sit over night it's all back to normal.