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Guru

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Hyde Reference Standard Wet Test Gas Meter

03/13/2017 1:49 PM

I want to build or buy, but the cost is not low, I think. I need to accurately and precisely measure flows of a mixture of two common, noncorrosive gases in the range of 0-500 mL/min, perhaps 0-1.0L/min.

Anyone have any strange ideas to share in this regard?

From Shinagawa meter web page:

【Wet Gas Meter Characteristics】
It is volumetric positive displacement type, which is used sealed chamber (drum) with liquid (water or oil), therefore, almost all type of gas can be measured without a influence of relative density and viscosity etc. Since this structure has no leakage, it can measure minute flow rate and have high reproducibility.

My plan is to not have a traditional dial readout with counters, etc., but use a sector wheel having up to sixteen sectors so that eight periods of the reflectivity per rotation is on the wheel. Apply this to a sensor that reports high and low to an Arduino, and count up the transitions, recording results in a logger file (SD card).

The real question is how would you go about making one of these bad boys? Would you take the material for the drums and vanes and fabricate in sections without weld lines, by press forming, then work all the sectors into grooves on the front and back sealing plates? Take two three four tin cans and make cut outs so the vanes join the smaller with the larger can? Need one more large can for the outer casing..by what I am seeing. Then you have to make sure it is water and gas tight, and provide for things like a temperature well, and a water level gauge glass with needle pointer (required for accurate calibration), and leveling legs, and a bubble level on the casing. Link to movie about setting up the meter: wet test meter set up

Thus far there is Maxiflo (S.Korea), and Ritter (English I think, but marketed in US) also as to brands out there.

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Power-User

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#1

Re: Hyde Reference Standard Wet Test Gas Meter

03/13/2017 3:13 PM

turn down is always a problem for these types of meters, your error from the number of sectors, liquid level and pressure compensation might be easily modeled on a conventional meter, with enough testing, like a turbine meter. IDEX makes meters you can calibrate on a 21 pt curve. might suit your needs. (?)

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Guru

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#2
In reply to #1

Re: Hyde Reference Standard Wet Test Gas Meter

03/13/2017 3:49 PM

Considering the method we are using now is water displacement to a load cell, I suppose so. Have you seen the prices of some of these meters? I am about ready to put a pinwheel inside a flow box, and call it good.

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Guru
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#3

Re: Hyde Reference Standard Wet Test Gas Meter

03/13/2017 4:34 PM

<...strange ideas...>

<...accurately and precisely...>

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#4

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 6:03 AM

Sounds like the sort of flow range for medical applications, and there must be meters on the market. But you've probably thought of that, and I don't suppose they're cheap either.

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Guru

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#5

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 6:10 AM

Sounds like the sort of flow range for medical applications, and there must be kit on the market. But you've probably thought of that, and I don't suppose they're cheap either.

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Guru

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#6
In reply to #5

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 9:00 AM

Thanks for weighing in. I am looking at a NIST paper on flow rate calibrations that is yielding some alternative ideas to the load cell unit (that still needs corrections for temperature and pressure, at least small corrections due to about 2 psi back pressure).

Consider a piston in a tube of known internal diameter. The travel of that low friction piston depends on the rate of admission of gas into the active end (other end vented), does it not? The issues arising would be whether local friction would allow for smooth gliding of the piston, or whether it would move in discrete amounts due to force required to overcome static friction. I can see this one takes about 4 solenoid valves to switch travel directions and start each measurement (timing) cycle.

Then there is the floating bell type meter with counterweight. That one is interesting, but how to vent the bell for a return cycle? Anything connected to the top of the bell would perturb the measurement of the rising of the bell. Could the return be a flexible tube initially stationed near the top of the bell, and that would definitely follow bell motion or at least remain above water line for venting off the collected gas at the end of a measurement cycle?

The wet test meters I have looked at do have a surprisingly good turn-down ratio.

Even the 0.5 L calibrated volume/rotation ones can do 1 mL/min to up 500 mL/min easily. Now if I could just get the Ritter guy (actually a German make) to hurry up and quote me.

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Guru

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#12
In reply to #6

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 1:08 PM

For the piston in tube type, my guess is the pressure at start of stroke will be higher due to stiction, but with luck it should then stay constant, and it's the pressure at end of stroke which you need to calculate the correction factor. Can you set up a water manometer on the inlet pipe, to give you final pressure and some idea about how it varies through the stroke? Sounds like the beer metering devices that were around 40-odd years ago.

On the floating bell type, can't the inlet and outlet pipes both come in through the liquid inside the bell?

Don't you fancy a Rotameter, as PW Slack's #3?

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Guru

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#13
In reply to #12

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 4:14 PM

I agree about the floating bell. There are pressure sensors I can hook up in Arduino land. Temperature also.

I would do a rotameter if I find one that is suitably calibrated and fine indexed scale, but those are not easy to find. It would do for a crude indication, but this is being measured ever so carefully for heat balance calculations. Electrolysis sort of goes like that, the amount of gas is nearly inversely proportional to the heat released per watt.

Besides, how does one data log a rotameter?

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Power-User

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#7

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 11:19 AM

Personally, I would 3D print the rotor in ABS on an FDM printer and seal it using acetone.

The key to this thing is the closed off chamber being filled with gas and freely floating. I'd achieve guidance of the rotor by running a length of spring wire across the center as an axle, putting sharp, centered points on either end of the wire and locating it between two magnets, so the point on one end is in contact with one magnet and the other is within a few thousandths of the surface of the other magnet (I made an extremely accurate balance cradle this way once.) Very free to rotate and the magnetic support makes the fluid level control less critical. The rotor is then statically balanced on the magnetic supports.

Put a printed wheel scale on the side or OD of the rotor and use an optical reader to read the rotation angle of the rotor.

At this point you could mount the whole thing in some sort of container with fluid level control, entry and exit porting and tubes and you are ready to go.

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Guru

Join Date: Mar 2011
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#8
In reply to #7

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 11:39 AM

Yeah, I do not have, nor have access to (1) 3D modelling, and (2) 3D printing.

I can sort visualize what you are exorting me to try, and I like the axle suspension by magnets, and I think magnetic coupling to any external counter wheel, or optical reader for angular measurement, is a fantastic way to make a good instrument.

Of course, there is always LMGTFY, to come in and lend a hand in finding someone to do the heavy lifting on this, at least as far as the spindle goes. I really like your way of thinking this into existence.

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Power-User

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#10
In reply to #8

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 12:11 PM

I happen to have a seat of SolidWorks and own two Dimension 3D printers. You want to do something with this?

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Guru

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#11
In reply to #10

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 12:34 PM

Sure. I want to steal the internal workings of a Ritter wet test meter, or at least mimic, since the folks there are dragging feets about quoting me.

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Guru

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#9
In reply to #7

Re: Hyde Reference Standard Wet Test Gas Meter

03/14/2017 12:06 PM

I found designer/maker services in Lubbock. I have no idea the cost yet. Maybe I can get this faster than my quote from the manufacturers.

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