Digital Flowmeter

Wow, you're looking for some very tiny flow rates. The flow rate is so small that the transport method of flow will be critical. At this flow rate you're talking about 5.4 mg/min, aka 90 μg/sec. The only thing I know that can possibly handle this kind of flow rate is parts of a gas chromatograph but this measures gas flow not a liquid. I hate to even think about how many complications surface tension and hydrogen bonding will come into play.

You're asking a lot. Good luck.

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Traditional vane, turbine or gear type flowmeters will not be able to handle such a low flowrate, and also probably ultrasonic, so you will likely need something like a coriolis flowmeter.

I have no connections, but this is a company I have dealt with in the past.

A Coriolis flow meter would have to be quite small to handle the 0.324 gram/hour.

I am thinking nano tech would be needed to pull this off..

http://www.brooksinstrument.com/flowmeter-flowcontroller-products/coriolis-thermal-mass-flow/coriolis-controllers-meters.html

Has a Coriolis meter and controller that can measure and control down to 1.0 gram per hour with a tube that is in the thousands of an inch in ID range....That is the smallest standard Coriolis I am aware of. BTW Coriolis is a proper name and should always be capitalized..

Ciao, Eric

Yes, you are right on both counts. I sit corrected. However, the smallest Bronkhorst model is almost there, getting down to 0.4 g/h.

I am going out on a limb here as I have not confirmed all these facts as true. I am not involved with either of these companies.

However the Bronkhorst High-tech Coriolis sensors are/were manufactured by Rheonik. Perhaps Rheonik directly makes a sensor that will fit the low flow build requirements.

It is interesting to see the similarities in the Brooks product line and the Bronkhorst High-tech products. Though not surprising as the Dutch engineers that started Bronkhorst all worked at Brooks years ago so the internet indicates…

The point is to this comparison is that as the original company has specs that rate a sensor at 1g/h. The follow up competitor seemingly to publishes spes just a tad better then the parent. I would really have to get into their cal system to believe the published specs for this reason.

All that's aside a min flow measurement capacity of 0.4g/hr still does not meet this app's requirements.

Anyone know of a marketed Nano Flow Coriolis sensor?

Eric

the best way is a calibrated dyed oil bubble in a capillary. You can get fairly precise capillaries, and you will need a source of clean water and a way to add a bubble and as it travels down the tube you track it against a ruler. A straight one foot tube has a smaller limit than a longer 25 foot coiled tube. The coil is harder to measure though. The other way is via a rotameter (falling bob in a channel whose cross section varies.

rotameter search

Just ask the NIST lab what they will be using to calibrate this.

If they are going to provide +/- 2% on a calibration certificate, then they also need to be able to source instruments capable of that resolution/precission/accuracy themselves.

We found this in photometrics, where we aligned our purchaes with the certification lab equipment.

try this link.

http://www.rshydro.co.uk/news.shtml

I've been in medical equipment repair for 20 years & that includes lab instrumentation & I have to agree with the others that your needs seem inaccessible. However, if you are able to take the instrument you are testing into a 'service mode' & then set various run times you may be able to weigh your output & then calculate flow rates. There are some very sensitive scales available & very portable if you take sufficient packing precautions. Of course you need to determine a base weight per volume for your flow product & calculate off that. I would guess that your product is getting mixed in with some other material & so 'normal' configurations for your instrument would have to be temporarily compromised in order to 'milk' the machine. Perhaps you can premeasure your product before you start & calculate flow by measuring your reservoir (weight/volume) after preset run times are concluded. For example pre-fill the reservoir (product feed) with a predetermined amount & run the unit for a set amount of time then remeasure your reservoir volume/weight. Etc. etc. Verification can be had by measuring the output (if available). Good luck. Carlos

Nano Flow Sensor, Thermal, 0.02 to 2 mL/min from Cole-Parmer.

NIST-traceable Calibration; Mass Flowmeter

	Measures liquid flows as low as 10 cc/day
	Straight-through design with no moving parts
	Excellent precision and chemical compatibility
The patented thermal measuring method of this flowmeter allows for the sensing of flow rates to 10 cc/day. One RTD measures the fluid temperature and the other RTD measures the temperature of a constant low-power heater which is cooled by the flowing fluid. The temperature differential between the unheated and heated RTD provides the primary flow signal. At higher flow rates, the cooling effect on the heated RTD is greater, so the temperature differential decreases. Since the cooling effect is a function of the mass flow rate, pressure compensation for gases is not required. The primary signal is temperature compensated, conditioned, and linearized by electronics to provide the desired output signals. The flowmeter's sensor cannot be damaged by over-ranging or by solids in the stream. It is ideal for continuous additive or catalyst injection at a low rate. Flow media can include adhesives, alcohols, colorants, fermentation feeds, hydrocarbons, liquefied gases, lubricants, and water/waste treatment. For more aggressive fluids, other alloys and metals are easily substituted. The sensor has a straight-through, unobstructed flow tube for minimal pressure drop, and the sensor design allows for chemical or steam sterilization in place. The standard 316 stainless steel wetted tube is compatible with most liquids and gases. Electropolished tubes can be specified for high purity applications. Contact an Application Specialist for more information. Flowmeter consists of a flow sensing transducer, separate electronics inmounted in a NEMA 4 enclosure, and 10-ft interconnect cable. Electronics have a two-line x 16-character display with infrared proximity and communications sensors, and have calibrated interchangeable signal conditioners. The two-line display shows flow, temperature, or total, and is user-configurable. As always no connections with the company. I've used a few products from them.