Measuring Instantaneous and Total Fuel Flow with a Pelton Sensor and Digital Readout

After shelving this aspect of my furnace 6 months ago, I got back at it and have found a good solution to reading flow rate and total fuel flow per session.

I found that most of the relatively inexpensive liquid flow sensors on the market are not sensitive enough to read in the range most of us need---.2 to .3 L per minute or 2.5 to 4.5 gallons per hour. What works and is accurate within a couple percent is combination of a Digiten Readout Unit (but sensor useless) and a Bio-Tech brand Pelton Wheel sensor made in Germany.

https://www.amazon.com/gp/product/B07G465DFR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

https://www.ebay.com/itm/Bio-Tech-FCH-M-POM-LC-AD-6-MM-Non-Aggressive-Liquids-Low-Flow-Flowmeter/143099898768?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

I had to work at figuring out the pinout of the Digiten unit to make it read the sensor, but otherwise the hookup was fairly simple. Then it was a matter of tweaking the "K-factor" of the readout so that the number of revs made by the sensor correlated with the volume of fluid that passed through it. That was pretty easy too---just compare the amout passed to the amount read and make a proportionate change in the K-factor.

Here is the unit in action---the annoying clicking is my 12v fuel pump driving the fuel flow.


The sensor comes with excellent documentation and wire ends to be used to connect the leads to the readout. The documentation tells which of the sensor pins is Gnd, 5V, and Signal. The Digiten does not. But I pinned it out and found that:
Gnd=White=Pin3
Signal=Yellow=Pin2
+5V=Brown=Pin1






Denis

 

Wow. Very interesting are you planning on doing a few experiments?

 

No experiments planned. I just like to know what fuel setting I am at so that I can tweak my burn for best heat. Until now I have been playing a guessing game of turning down the fuel "a little" and then reducing air "a little" to try to hit the sweet spot. Now, I should be able to set my fuel rate and then adjust air to match. I do have marks on my air shutter that help me hit a given level of air flow, but without knowing fuel flow, really never was sure of what was going on. So, this reduces one more previously uncontrolled variable.

Denis

 

The remaining thing to do on this is to make a reasonably robust enclosure to encapsulate the sensor and readout and get the wires etc out of harms way, but still have the parts easily serviced and the screen readily visible along with the face of the pressure meter.

Denis

 

Very good work!!

 

DAMN! That's some high speed low drag stuff there! The fuel flow measuring equipment on my airplane isn't even THAT sophisticated! My best measuring device to know whats left in the tanks is strapped to my wrist! It's called a timex!

What you've got there looks like what's on my water softener system. It predicts usage for tomorrow and decides if it needs to regenerate tonight. Saves salt big time.

 

It is probably similar at least in principle to the softener but the big difference is likely the low-flow accuracy. Homes use water at the rate of many liters per minute usually. Sensors in that range are very common. The trick is to find one that actually works (registers at all) and is accurate at low flow rates of part of a liter per minute. I bought two sensors from eBay purported to work at low flow that don’t even start to turn at less than a liter per minute (15 gal per hour). The one shown in this thread I have worked with over 15 or more times and volume measured intervals and it is good over the range of .1 liter per min on up.

Denis

 

Yeah that's pretty DOB (dead on balls) accurate!

 

I put in a little time mounting the flow meter and pressure gauges to make ready for use in the foundry. Here is a 2 min video of the setup.





I probably will enclose the “guts” more completely in the near future. But I will leave them somewhat exposed for the first couple shakedown melts to be sure no modifications are needed.

Denis

 

Dennis, this is all very neat! Thanks for starting this post!

I think it is absolutely beneficial when trying to figure flow rates just a glance. Some guys say 60 mL per minute works great and some guys 250 mL per minute, and everything in between.

There are brushless DC pumps for very accurate dosing in the medical field. These pumps are notorious for non-cloging but they have a small pulse to them. They use two, three, four… eight rollers. The roles role against a stretched out silicone tube. They work very similar to a water wheel. Depending on the RPM and the size of the tube, dictate a very accurate pumping rate. These start at $100 and go upwards into the thousands of dollars. They are a very neet all in one pump.

I am going to try a miniature needle valve used in pneumatics for pre-flow fuel. But I’ve said it before I do not fancy needle valves. I worked most of my life in an industry that has contaminants and sediment. I am sure the first time I have a fuel clogging problem because of a needle valve I will be kicking myself first.

 

Dennis, I’m wondering if you have the needle valve flow control after this whole assembly?

 

Well, if you have a flow meter on your system you will see there is a problem immediately and you will know immediately when it is cleared.

Denis

 

Yes, that is how I adjusted the flow rate from .27 to 0.0 and rates in between. I have used a needle valve from the getgo without trouble in over a hundred melts. Filtration of the fuel occurs after the needle valve in my setup. maybe the filter should preceed the valve but I wanted the filter to be the last thing the fuel passes through before entering the nozzle as that is the part of the system most sensitive to dirt.

Denis

 

Thank you very much. I’ve been trying to create my nozzle so it’s not sensitive to dirt. Now I’m trying to figure out how to make everything before the nozzle non-sensitive to dirt, (saturated fat).

 

Fancy Schmancy! When can I place my order for one? Do I get a warranty?

 

You can place your order any time. “Your delivery may time may vary”. Uh, don’t hold your breath...

 

I thought my compressor today was taking it's sweet time starting back up after 10mins and I thought about your pump. That thing not cycling back on during a melt is the stuff bad dreams are made of. It did it once to me and I haven't trusted it since then. Time to change that switch just because.

 

What about pumping your dirty fuel through a sedimentor – as found on diesel cars – and then through particulate filters –also found on cars – and then into a clean tank. After the clean-tank the fuel can be sent to the burner at your leisure; it would be easier to have two pumps i.e. treat the dirty fuel treatment as a separate system to the furnace.

If you find a popular model at the wreckers, you should be able to get the parts quite cheaply, as they are slow-moving parts and new filters should not cost much,

Cheers Charlie

 

My wreckers have a direct line to dealership prices. Everything is HALF... I swear they sound like an ex wife. Rockauto.com is the place for NEW cheap parts. My junkyard isn't worth the time. Sad really, my wife loved to chum around a junk yard looking for treasures.

 

Where this would be beautiful, is to be able to measure a difference between a constant fuel (like diesel) and waste oil using the same amount of combustible air.

Maybe Jason has these numbers as he switches with a constant air source

@Jason do your gallons (/L) per hour stay consistent between the two fuel sources with a steady stream of combustible air? ... or is one fuel more efficient???