Question for All of Your Manometer Installs

2001Sierra wrote:The fact that the fluid absorbs, and therefore becomes contaminated is nice to know. Kind of like brake fluid over time. Something to consider and not ignore.

The only thing to consider is if the actual weight of the fluid changes. It is calibrated to reflect a specific weight of the fluid used compared to water.

Just thought I would share with you guys regarding the manometer fluid. They recommend replacing it yearly
With how critical the draft is just thought I would put it out there. Wonder how your readings would change with new fluid.

I did not know that,

any body with hands on experiance when changing fluid as to how the meter reacts???? Does the specific gravity of the fluid change with time?

Since we only hook the mano up to our stack systems with just one side of the mano tube (the other side open to room air) and there's a constant negative pressure on that side, I don't see how it could become contaminated with any combustion byproducts.

I work with hydrostatic level gauges, both single and double line systems. They work similar to a manometer on very slight pressure differences.

The single line type (like we use with the stoves), don't get contaminated by the fluids that they are measuring the level of.

However ( like your HVAC use), the double line type eventually do get contaminated and need periodic gauge fluid replacement .

Paul

Not trying to start a fight but that is off of dwyers page. It shows the same one on the FAQ page. You also absorb just the garbage in the air. Everyone uses that meter and doesn't think about changing the oil. It says with just dirty air. Remember just the humidity in the air will change the gravity over time.

Junk in my air ? Never !

Yup not looking for a scrap either. Just trying to answer your question.

My Dwyer info mentions that the liquid is an oil, but doesn't say what type. And, it doesn't mention if that oil is hygroscopic like brake fluids. If it were, I think we'd be seeing a color change, or clouding of the oil, like happens with moisture contamination in some known hygroscopic oils.

So, I looked up the MSDS for it on the Dwyer website for the red liquid. It lists it as mostly petroleum distillates, hydrotreated light, which is the same description for mineral spirits, ..... aka low VOC paint thinner. I'm no chemist, but as far as I know, mineral spirits is not considered to be hygroscopic, so I'm not concerned about moisture absorption throwing off the SG.

I check the level on my Dwyer 25 about once a month and about every two-three months it's shows that it's lower by maybe, as much as .002 on the gauge. Color wise, the fluid has remained exactly like the extra fluid in the bottle of oil that came with the gauge, which has remained sealed and stored away since I first set up the gauge a year ago.

Has anyone changed their red liquid and seen any difference ?

Paul

You're inferring that the fluid is becoming contaminated with the exhaust stream impurities but you are measuring a NEGATIVE pressure so no impurities are being forcedd INTO the fluid. Instead, the fluid is trying to be drawn into the airstream. No impurities go up the tube.

No impurities in the tube because air doesn't flow thru the tube period. Right?

Sunny Boy wrote:Has anyone changed their red liquid and seen any difference ?

Mine is 4 years old, same fluid. I do the same as you and recalibrate it every once in a while. Precise measurement of the negative pressure isn't necessary. So what if a reading of -.04 is really -.041 It's more a relative measurement away from "zero" that's important..

Ok I have 2 u-bend manometers. I use 1 a lot. Almost daily for 4-5 hours a day. The second I use maybe 4-5 times a year total. Both are 3 years old same fluid in the second one. The first one I gent up changing every 6-9 months. When #2 is not in use I have plugs that don't allow air in or out and also won't let it spill. I used # 2 today in work. Numbers seemed ok. Brought it home checked the draft on my 105 keystoker. It said my draft was .03. Changed the fluid then my draft was a .01. I got my calibrated draft gauge out and confirmed it was a .01.
All I'm saying is people on here will buy multiple gauges set cameras up to monitor them. But won't spend 10$ to perform routine maintenance as per manufactures recommendations.

Fwiw,

My Dwyre has "red oil", I have never had to add any. It smells like mineral spirits.

Baro dampers are pretty dumb. Depending on weather, my draft can change as much as .3" Knowing what I've learned here, I would not consider being without the gauge.

Dave