GREDIA 3/4" Water Flow Sensor Food-Grade Switch Hall Effect Flowmeter Fluid Meter Counter 1-60L/min (Pack of 2）

Great replacement for the flow sensor on my Red China laser.

Works well was easy to setup. Using with an arduino uno that has an lcd display to measure total volume and rate of a variable rate spraying system. Read the description. Make sure that the sensor will work for the volume per minute you need measure.

title sums it up for me, i added enough Teflon tape, screwed everything together (no leaks) and started coding. for this project i used 2 GREDIA G2 2" Water Flow Sensor/Switch Hall Effect Flowmeter Fluid Meter Counter 10-200L/min (model GR-216). my pump is rated for about 80gpm accounting for 90degree elbows and piping i was suspecting about 60gpm all said and done. After physically measuring my flow rate and modifying my initial code i ended with a flow rate of about 57.75gpm so these get a thumps up from me. here is my initial starting off point with my Rpi3/python code wise, feel free to use it (i monster-iz-ed a couple code snip-its i found online) only thing i don't 100% understand is at the very end of the code i have to multiple gpm by 2 to get close to what i physically measured. only logic i can use is maybe this/these sensors have two pulses per rotation other than that i have no idea, it's avg. rate is at about what i measured (+-1.6%) so it's good enough for what i'm using them for. ## This if for 2 GREDIA G2 2" Water Flow Sensor/Switch Hall Effect Flowmeter Fluid Meter Counter 10-200L/min (model GR-216) ## This code is not 100% accurate but is close enough for measuring coolant flow in a cooling system ## physically measure a flow rate of about 6.44531 gpm; sensor avg. rate is 6.342 gpm a difference of about 1.6% #!/usr/bin/python3 import RPi.GPIO as GPIO import time, sys FLOW_SENSOR = 4 FLOW_SENSOR2 = 17 flowCalibrationFactor = 0.2 # Note: F=(0.2*Q)±2% for this flow sensor, Q=L/Min, and F is pulse freq in 1/s global oldTime global count global count2 oldTime = 0 count = 0 count2 = 0 GPIO.setmode(GPIO.BCM) GPIO.setup(FLOW_SENSOR, GPIO.IN, pull_up_down = GPIO.PUD_DOWN) GPIO.setup(FLOW_SENSOR2, GPIO.IN, pull_up_down = GPIO.PUD_DOWN) def main(): GPIO.add_event_detect(FLOW_SENSOR, GPIO.RISING, callback=countPulse) GPIO.add_event_detect(FLOW_SENSOR2, GPIO.RISING, callback=countPulse2) while True: try: curgpm = getFlow() print("GPM: %s" % curgpm ) time.sleep(1) except KeyboardInterrupt: print('\ncaught keyboard interrupt!, bye') GPIO.cleanup() sys.exit() def countPulse(channel): global count count = count+1 def countPulse2(channel): global count2 count2 = count2+1 def getFlow(): global count global count2 global oldTime start_cnt = count + count2 readcnt = 0 while readcnt < 1000: time.sleep(0.001) readcnt += 1 end_cnt = count + count2 pulses = end_cnt - start_cnt # Note: F=(0.2*Q)±2% for this flow sensor, Q=L/Min, and F is pulse freq in 1/s gpm = ((1000.0 / (round(time.time() * 1000, 5) - oldTime)) * pulses) / flowCalibrationFactor*0.26417287472922 #gph = ((1000.0 / (round(time.time() * 1000, 5) - oldTime)) * pulses) / flowCalibrationFactor*15.8503 pulses = 0 oldTime = round(time.time() * 1000, 5) return round(gpm, 3)*2 if __name__ == "__main__": main()

I haven't finished integration, but initial tests are very positive. I am running this meter on 3v and so far it's working great. I think there's a small paddlewheel inside that spins to count flow; I don't have measurements on precision yet, but the numbers I'm seeing show it to be quite sensitive indeed. I've connected it to a SEEED Xiao ESP32C3, and configured it with ESPHome as a pulse counter, and then integrate that pulse counter into a volume measurement. I still have some work to do on the calibration, but very pleased with this so far. I haven't compared it to others, and I think there are some improvements to be had in sturdiness (it's cheap plastic, but that's obvious from the photos), but overall I am excited to have a working meter.

I've adapted this Gredia GR-201 1/2" flow sensor paired with a Digiten Flow Meter to monitor flow rate thru a UV sterilizer. The sterilizer I have requires a flow at 37 GPH optimum and 60 GPH max to be effective eradicating protozoa. Out of the box the pairing of the meter and sensor was way off reporting 16 GPH while a had a gate valve nearly closed. So to calibrate it, the meter has a K-factor value that has to be adjusted to the sensor you pair it with. The default was a K-factor value of 1.98. I did a Google Bard search for what the sensors K-factor should be... 11.45. I set the meters K-factor to that. It was much closer but not accurate. I adjusted my valve until the meter was reading 1 GPH of flow. I set up a bucket to divert the water exiting the system into so I could measure the amount dispensed in a minute. I recorded .453 gal. with the K- 11.45. Now a little math, divide the current K- (11.45) by the flow it produced (0.453) while the valve restricted flow with the meter reading 1 GPM. The resulting new K-factor of 25.27 worked precisely. Well, as precise as using a large measuring cup to measure the amount of water dispensed. I re-ran the test, I got 1 gallon at the 1 minute mark, 3 gal at 3 minutes. The one annoying thing about the meter is the backlit display goes dark after 15 seconds. Annoying during the calibration when your hands are busy turning on/off a pump and a timer. But in actual use I'll only be using this to set the gate valve position and the backlighting won't so much be an issue. I hope this helps those trying to get a more accurate reading.

the way this unit is designed it blocks of a full 1/2 of the flow so it can direct the rest of the flow into the paddle wheel. Any time you run water through a reduced opening it causes substantial pressure drops at higher flows. The way these units should be designed is so they widen first so when the block off part of the area for the wheel it still leaves a full 1" diameter open. If they had done that it would not have caused such a large pressure drop. It may work ok if you place 3 of these parallel but that is a lot of 1" fittings to pay for.

Works. Definitely seeing the +/- 5% difference in output. A few things I discovered: * The sensor needs at least 8V. I had a 9v power supply left over from some other equipment. However, a raspberry PI can only take 3.3V into its GPIO port. (and no pull-up resistor is needed) So I sent 8V into this sensor, and on the output pin I installed a 10k resistor tied to ground. This dropped the output voltage to around 3.7V. * I wanted to record data in gallons per hour. This is from my most recent calibration where I dumped water into a bucket marked off with quarters of a gallon on the side. total_gal = total_gal + 0.001115 # 897 pulses per gal = 0.001115 gal per pulse. This code runs whenever a change from high to low occurs on the output pin. flow = (count / 897.0)*3600 # pulses/897 is gal per sec. *3600 is gal per hour * the label faces down. There is a lot of play in the spindle inside. making the label face down puts the impeller more directly in line with the water flow * make sure you install it in the right direction. The arrow on the label was correct for me. * I used waterproof automotive plugs, sealed on the ends with caulk, since this thing will be outside measuring the irrigation water usage.

I bought this to monitor water flow on my home's water main. I connected it up to an ESP32 with ESPHome on Home Assistant and it worked well to count the pulses and report gal/min etc. So it works as advertised in terms of measuring water flow....however there a few problems. Firstly, the listing says it is BSPT (British Standard Pipe Tapered)... this is not true. This is actually BSPP (British Standard Pipe Parallel). This means it needs a BSPP adapter to NPT if you want to use this in the US. It also means that that the sealing is done with an o-ring. I purchased the adapters on Amazon but the o-ring seal that came with it was on the inside (like a garden hose).. The threads are not long enough on this device to seat against the o-ring.. so it leaked badly. I tried using PTFE wrap... it leaked... I tried thread sealer... it leaked. Everything I tied leaked at my mains pressure. Then the leak got bigger until BOOM! The threads blew off. Thank goodness I was still standing there to shut off the water. After a day of pondering my life choices up to that point, I decided to purchase the brass version sold by this company. This was also BSPP. I had also purchased dowty seals of the appropriate size (after tons of research on british plumbing standards)... I was able to get a good seal with the brass version with dowty seals and PTFE as a back up. I would say, don't buy this for anything more than a few PSI of water pressure... its way too risky given the catastrophic failure I witnessed. spend a few extra dollars (literally only a couple more bucks) and get the brass version for higher water pressures (like your home's water main).