Linkert Floats

Linkert related issues
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Cotten
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Re: Linkert Floats

#91

Post by Cotten »

WZ507 wrote:Attaching a syringe to the end of the sight-glass tube and applying vacuum to the tube should pull a stream of fuel through the sight-glass circuit that should quickly purge it of any air present. Conversely, one could inject a stream of fuel through the sight-glass tube to assure it was free of air.
That is why I resorted to the squeeze-bulb, of course.
WZ507 wrote:If you find that disturbing think what you might see in real world use (where vibration and all other forces are at work)!
Sediment is always disturbing, and that is about all a glass bowl would show on the road.
heitgr2.JPG
Actually running a motorcycle with an apparatus, even a "glass bowl", never seemed reasonable to me. It would require an observer in a sidecar at best.
My intent is to investigate upon the workbench.
WZ507 wrote:The 2 above observations regarding the sight-glass circuit reacting excessively to main nozzle flow and bowl draining indicate that the tap for this circuit is too close to flow sources (main nozzle and bowl drain), and the sight-glass circuit "feels" the pressure differential associated with the change in flow associated with either draining the bowl or pulling on the main nozzle.
At this point, the sightglass did indeed appear to act like a circuit!

As shown in my photos, the sightglass and drain are both tapped equally below the bowl entirely.
The simulated bowlstem has a gallery that I will probably tap for a jet, located at the same height as jets. It can be shimmed as necessary, as I have other bowls to investigate.

Either drawing upon the distant "nozzle", or opening the adjacent drain quickly pulled air from the sightglass long before the bowl level reached the 'main' gallery.

First I must find time to collect the static data:
The OEM cork should produce a level of 5/8" when shut, or so I have read, and guestimated myself previously.

Let us see what we get, if it reproduces, and if the sightglass scale is meaningfull.

I'll be lucky if I can even take a pic of it today...

....Cotten
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Cotten
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Re: Linkert Floats

#92

Post by Cotten »

A set-back Folks..

In time, if not in progress.
This scrap of plastic rod stock reappeared after three decades in my raw materials stash, and I promptly cut 3/4"-20 threads to replace my brass hex attempt.
CLERSTEM.jpg
SITGLS10.jpg
The gallery bores are all under-sized for now, as I wish to observe things on the simplest of terms to begin with.
Now I can also measure heights much better.
sitgls11.jpg
Can't wait to get her wet again,

.....Cotten
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awander
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Re: Linkert Floats

#93

Post by awander »

Cotten:

Are you using fuel, or some other liquid, in your tests?

Cotten
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Re: Linkert Floats

#94

Post by Cotten »

Andy!

I thought somewhere we already discussed putting a dye in mineral spirits.
(At this point, it may only need to be just what I wring out from the pooltable felt beneath the leaky thing.)

Mineral spirits is safer than fuel, produces a flatter meniscus than water, and hopefully will not bubble so much if I am carefull.
(Modern fuels commonly have anti-foams, which also may contribute to fuel digestivity.)

The necessity for vibrations of some sort may still prove necessary.
And its not just because I have vibrators stashed somewhere.

....Cotten

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Re: Linkert Floats

#95

Post by awander »

Yeah, that does ring a bell.

I wonder if the anomalies you observed when emptying the nozzle bore could have anything to do with the different viscosities of gasoline and mineral spirits?

From what I have been able to find, mineral spirits is approximately twice as viscous as gasoline.

Cotten
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Re: Linkert Floats

#96

Post by Cotten »

That's useful to know Andy!

But different fluids have different surface tensions as well.
Thats what makes it difficult to read water in a thin tube, and makes fuel crawl up the insides of the bowl.
Unfortunately, it is also what bubbles are made of.

Mineral spirits is as fumey and flammable as I wish to work with indoors. And it cleans up easiest.
If its higher viscosity slows its reactions a bit, it might just make things easier for us to observe and measure.

....Cotten

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Re: Linkert Floats

#97

Post by 58flh »

I think thats a good idea.After you get what data your looking for/Its unevitable to take the rig outside & use gasoline!--& see what difference there is.Maybe by doing like that ,you could use the mineral-spirts & know what to add or subtract in the future!---just a thought---Richie

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Re: Linkert Floats

#98

Post by awander »

I certainly understand not wanting to use gasoline.

My concern is that the very thing that makes it easier to observe will also slow down it's flow rate in/into the nozzle bore.

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Re: Linkert Floats

#99

Post by Cotten »

Uh-oh Folks,

Viscosity is a lesser concern (twice next to nothing is still next to nothing) than specific gravity:
VLUMTRCS.jpg
This year's P4gas is .241, whereas some fresh mineral spirits is .296, or one-fifth heavier.
Fluid levels would certainly change with added buoyancy to the float..

Or will they?

....Cotten
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Last edited by Cotten on Mon Jun 24, 2013 9:18 pm, edited 1 time in total.

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Re: Linkert Floats

#100

Post by awander »

I'm not a chemist, and my knowledge of fluids is not what it once was(and even that was not so much)....but I think both are important.

My research showed that gasoline and mineral spirits were pretty close in density or specific gravity-certainly closer than they are in viscosity.

I don't want to discourage the experimenting, just want to keep thinking about it.....

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Re: Linkert Floats

#101

Post by Cotten »

Andy!

Thinking is only conjuring without any data, so we need to also encourage others to reproduce findings, if there are any.

Its been well over a quarter-century since I was schooled and worked with fluid dynamics, and most were extreme pressure-viscosity circumstances. One was even "non-Newtonian". And I never really had the math under my belt.
So that's why I wish to tinker-toy the simplest means to first observe the basic nature of our system, and then complicate it by makeing it more similar to the carburetors.

The first step is to determine a fluid level that we can call a baseline that we believe was the original.

I have little available R&D time.

....Cotten

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Re: Linkert Floats

#102

Post by john HD »

I have little available R&D time.
and i have none due to my new job.

that's what makes it so much fun to follow along after hours!

keep up the good work!

john

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Re: Linkert Floats

#103

Post by WZ507 »

Its good to play devil's advocate and be concerned about all factors involved in an experiment, since such efforts often produce high quality reproducible data when conducting the experiment. So far several concerns have been expressed regarding physical properties of the test solvent - surface energy, viscosity and density. I agree that these factors may introduce variability to our system, but then we have to ask ourselves the question "what level of variability is important to us?" I think to begin with we are after some very basic info on how bowl fuel level is affected by different floats (baseline fill levels). Then we might want to look at fuel replenishment rate as a function of fuel drain rate.

So, could the factors recited above influence the experiments described above? Sure they could. But the real questions then become "how much of a difference will any of the factors make?", "is our measurement system capable of detecting minute differences" and "do we care about minute differences?"

My intuition is that surface energy and viscosity are not critical parameters and if we disregard them we will not be lead astray. I say this because any hydrocarbon test fluids we choose will have relatively low surface energy and will therefore readily wet any of the high surface energy metals of our test rig. This should be the only real concern regarding surface energy of the fuel. Therefore, small variations in the surface energy should be a non-issue for us.

The viscosity of the fluid will absolutely alter it's rheology (flow properties), but is it something we can measure and will we be probing in a regime where it matters to our results? I think not. But if it did matter, it would likely show up in fuel replenishment/drain rate experiments exploring relatively high drain rates. As someone said earlier, sooner or later the test rig will make its way outdoors, and gas testing should reveal any differences attributed to a higher viscosity test fluid.

That leaves the variable of fuel density, which as Cotton points out, might make a difference "or will it?" Gas is a complex hydrocarbon mixture that can vary in density from ~ 0.70 to 0.77 g/cc. Density variations can be caused by a variety of factors including; seasonal composition changes, energy content, additive package, etc. The brief searching I've done shows the density of mineral spirits to fall near the top of this range at 0.75 to 0.78 g/cc. From this information it would appear that depending on which gas sample and which mineral spirit sample one obtained, they could be nearly identical in density or at the extreme the spirits might be up to 11% higher density. This is a factor we should likely keep track of if the fuel changes.

If we want to determine how/if density over this range affects fuel level in the test rig, we could blend solvents to provide a range of density from 0.7 to 0.8 g/cc and see if the test rig can detect differences. For example if we had a sample of Coleman Camp Fuel (d= 0.69-0.70 g/cc) and toluene (d = 0.87 g/cc), these materials could be blended to obtain any density from 0.7 to 0.8 g/cc (a 50/50 volume blend would provide a density of ~ 0.78 g/cc). The down side to these solvent systems is that they have to be used outdoors or in a fume hood. But if we want to know the effect of fuel density on the system, there's a way to do it.

Cotton,

Since adding the clear stem to the system have you changed the internal orifices, or will the sight-glass circuit still be exposed to pressure differentials associated with flow to the main nozzle and drain?

What did you use as a reference to come up with the specific gravity numbers you have? Or better yet, since you are using volumetric flasks for weighing, what was the actual density (g/cc)?

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Re: Linkert Floats

#104

Post by Mr.Big »

Whut?

Cotten
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Re: Linkert Floats

#105

Post by Cotten »

WZ507!

I miss-read my own notes! Please allow this correction:

Density, as specific gravity, is measured relative to water.
The 100 milliliter volumetric flasks are first "tared", or weighed empty and marked.
They are then filled to a precise line (properly at 20°C), and then weighed.

Subtracting the weight of the flask gives the weight of the contents.
100 mls of water weighs 100 grams, or one gram per ml (which is conveniently a cubic centimeter.) The specific gravity of water is 1.0

But 100 ml of mineral spirits weighed only 78.7g, or so its sp-gr is .787;
And 100 ml of P4gas (Shell premium) weighed 73.3g, sp-gr .733.

So the difference is not as dramatic as I feared!

Only an empirical test will tell us how significant it is.

Rather than theorize, I need to gather observations and data from real life, for my feeble comprehension if nothing else. My apparatus is intentionally in a very raw form, as I must double check myself constantly.

More when I find the time,

....Cotten

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