Water gauge

[GNNOVA]

Well my flowbench is almost done and its time to build my water gauges. The question I have is about the gauge used for working pressure. The norm is 28" of water. If I understand it correctly I need a 28" column of water capable of mearsuring pressure and vacuum at this level. Does anyone have pictures and design basics for this setup?

[larrycavan]

[GNNOVA]

Thanks for the link Larrycavan. Thats what I was looking for.

ken

[ddracing]

I'm pretty green to this right now but wondered if you could use the digital manometers that they make in place of the water tubes. I see that they measure positive, negative and differential pressures. I'm not needing a certain number like CFMs but a referance number to tell the changes between carbs. Sorry for my lack of knowledge here but may try building a small flow bench for Walbro carbs & am trying to simpify the guage deal. Thanks.

[bruce]

I'm currently working on a set of water gages to compliment my flowbench plans using a 12" Delta P (scale height).

While I'm doing this I can also workout scales for 10", 6" and 3" Delta P for smaller benches. I'm laying out my scales using my CAD software based on a percent of flow. Doing it this way makes it easy for the DIY'er to cut and paste the scale together manually for the 12" Delta P and the smaller scales would fit on a legal size paper for printing.

Using the manometer spreadsheet one can use a milling machine to also layout their scales once they have something working with the paper scales.

Using one of my orifice plates you can then calibrate your internal orifice and scale angle.

I'll keep the forum up to date on my progress with this project . . .

PS I can't believe I'm messin' with water gages again!!

A Special Thanks go out to Larry C. and 86Rocco (Ed L.) for their help in this project!!



Edited By bruce on 1199797382

[Tony]

Here is a link to my flow bench, but the first picture at the top shows the bottom half of my test pressure manometer.



Doing it this way with a reservoir replacing the other half of a "U" tube makes the thing much easier to fill and correct the zero point with a small syringe. Fluid can easily be removed, which is rather more difficult with a U tube manometer.

Another big advantage is a normal inch scale metal ruler can be used to read off the test pressure directly in inches.

With a U tube, one leg goes up, the other goes down, and it can be a nuisance to read the exact distance between the up leg and the down leg,

[MMack]

Tony, your idea with the reservoir has helped me a lot. I drove myself crazy trying to fill the U-tube and get it to zero! I thought I was being very smart and made them out of PVC pipe, with the pipe section long enough to use a two hole conduit clamp to suppport it to the back of the bench. Easy to zero, just slide the pipe up or down and tighten up the clamp. That worked well. Then, while picking up the parts to make it I noticed the clean outs. Hey this will make cleaning, filling, etc easier. This caused me more grief than I ever would have believed. I have spent a good bit of the last two months chasing a 32cfm leak around my bench. I finally changed orifices to see if it stayed at the 80% it was with the 40 cfm plate, and it was still 80%. Changed to a bigger plate, and it still was 80%! This got me thinking about a gauge error. Started checking the readings with another gauge, and everything looked good! I was staring at the bench trying to figure out how bad it would smell if I lit it on fire( thankfully it is far too heavy to drag out of the shop to light) when I noticed the cleanout. I grabbed some pliers and tried to tighten it, and it moved! Now we're down to 60%, give it another pull. Now we're down to 40%, then 20%, then 10%. A quick dab of RTV and we are close to zero, time to move on. Now I have my bench back, and it works great. What a PITA from a "good idea".

Reservoirs - good, very good
Cleanouts - bad, very bad

Mike

[Tony]

Plastic threaded fittings can be a problem.

My top threaded male plug is a fairly soft black thermoplastic (as used in irrigation systems) and it screws into a standard tapped brass female threaded plumbing fitting fairly well. I can imagine that plastic screwing into plastic where the threads are both molded, not cut, might be a potential leak, without something like teflon tape or silicone sealer.

Leaks can be very frustrating things to locate. I have had great success with a bucket full of soap suds. Great hand fulls of bubbles in various places quickly locates any problem.