Manometers - Selection, application, etc...

[5.0joe]

I plan on using Dwyer manometers (U-tube and inclined) in my soon-to-be orifice style flow bench. The U-tube selection is pretty straight forward. But for the inclined, I haven't yet decided which one I will use. I was actually looking at the Mark II series (about $200 cheaper). It is only +/- 1% less accurate than the more expensive inclines. I am assuming I will probably need something that has a range of about 0"-4" W.C. if I am testing at 10", which I plan to do. I'm sure everyone has their preferences when it comes to manometers. I'm interested to hear the differences and downfalls of one particular compared to another.

[thomasvaught-1]

The dwyer Inclined manometer Part Number 246 is the manometer used by all of the SF flow benches (300, 600, 1200). It uses red .826 specific
gravity fluid and has a 6" H2O pressure drop at full scale. It is a nice looking manometer being made out of a solid piece of plastic. It has an adjustable zero and also a leveling bubble. Nice features.

An additional 2" of water orifice depression with a scale length of almost 20" (19.85" actual) will give good readings. One of our members I believe is making a Percent of Flow scale for the manometer too.

I realize that money is a big issue for some, but I would think that would be a good manometer.

Bruce is helping some guys who have made their own inclines and "U-tube" manometers but if you want to buy a professional manometer that would be the one I would recommend.

Tom V.

[Tony]

If Dwyer manometers are within your budget, just go fully electronic to begin with.

Otherwise, some home built manometers can be every bit as accurate as the commercial product, and cost almost nothing to make.

[5.0joe]

Wow, I see that the Series 246 is about $400...wasn't expecting that. Maybe I shall go with electronic, as they appear to only be about $140 each, and they measure absolute or differential pressure. I wonder if I could get away with just one of these, and maybe disconnect one connection to measure the test pressure, then connect both lines and swith the manometer to measure the differential pressure?

[bruce]

Just build water gages, here are a few pics of one I am working on for the PTS plans bench. It uses Gofaster/Heads1st's professional scale he sells.





Edited By bruce on 1203629180

[bruce]

A closeup of the scale, kinda hard to photo since it's mirror polished

[5.0joe]

Building a manometer would save money and be a learning experience in itself. However, as the deadline is only getting closer for completion of this project, I want to speed up the process as much as possible, without cutting corners. I read one of the threads about building your own manometers and what it entails. It does not seem too extremely difficult. Since I have outside funding, I think I will purchase the manometers and apply the time it would take to build one to other areas of the build.

[5.0joe]

p.s. Bruce, I should be calling you soon to purchase an orifice plate for my flowbench. Look forward to talking to you!

[5.0joe]

Anyone have a Dwyer series 246 manometer for sale possibly or know of a vendor where I can find one for less than $400 (Dwyer price)?

[thomasvaught-1]

I have a new one I would sell for $340.00, plus shipping, that will come with the normal 6" "Ruler" type scale. You can purchase a square root scale from one of the board members for the 246 manometer. It will come with-out the red .826 fluid but that is easy to order.

Tom Vaught

[5.0joe]

What do you recommend as far as the scale on the inclined manometer? The reason I ask is because this is for a project, and when completed, I plan to donate it to the school for future students to use as a lab apparatus. It will come with a lab manual with an experimental procedure and data to collect, and then resultings calculations and graphs. So, I almost feel like it would be better to use the ruler scale, rather than a percent flow, etc. and have students plug the values from that scale into the equation to find the flow. There is not going to be any electronic calculating software with this. The point will be for students to demonstrate an understanding of theory through the application of formulae. Also, Dwyer has the pressure conversion charts on their site, converting in. H20 to psi, so using that and the pressure difference on the inclined manometer, you can convert this into the psi difference and plug it into the equation.

[86rocco1]

You might consider doing both, that would be a rather graphic illustration of the relationship between pressure and flow and it would be reinforced every time the students looked at the flowbench.

[thomasvaught-1]

MMs of H20 to Inches H20 using a simple meter stick and a conversion program for both the verticle manometer and the inclined manometer
would be educational.

The square root scale gives you quick percentages but a meter scale and a computer spreadsheet will give you exactly the same results AND you will show people how to build their own instrumentation.

I have no issue either way on whether you want to purchase a professional unit or build your own.

Until you build your own though you will never truly understand the way that everything works, IMO

Tom Vaught

[racehead]

Hi Tom,

Have you received my email???? :p

[bruce]

Here are a couple of new pics showing the % scale mounting on my homebuilt manometer: