--- product_id: 143719307 title: "1/2\" Water Flow Sensor Food-Grade Switch Hall Effect Flowmeter Fluid Meter Counter 1-30L/min (Pack of 2）" brand: "gredia" price: "141 zł" currency: PLN in_stock: true reviews_count: 11 category: "Gredia" url: https://www.desertcart.pl/products/143719307-1-2-water-flow-sensor-food-grade-switch-hall-effect store_origin: PL region: Poland --- # Food-grade, ROHS certified plastic G1/4 inch male thread fit 1-30L/min flow range 1/2" Water Flow Sensor Food-Grade Switch Hall Effect Flowmeter Fluid Meter Counter 1-30L/min (Pack of 2） **Brand:** gredia **Price:** 141 zł **Availability:** ✅ In Stock ## Summary > 💧 Flow with confidence, measure with precision! ## Quick Answers - **What is this?** 1/2" Water Flow Sensor Food-Grade Switch Hall Effect Flowmeter Fluid Meter Counter 1-30L/min (Pack of 2） by gredia - **How much does it cost?** 141 zł with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.pl](https://www.desertcart.pl/products/143719307-1-2-water-flow-sensor-food-grade-switch-hall-effect) ## Best For - gredia enthusiasts ## Why This Product - Trusted gredia brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Dual Pack Advantage:** Two sensors included to double your monitoring power or backup your critical systems. - • **Precision Flow Control:** Accurate ±2% measurement ensures flawless fluid monitoring for your smart devices. - • **Robust & Safe Materials:** Crafted from food-grade plastic, fully ROHS compliant for health-conscious professionals. - • **Universal Compatibility:** Seamlessly connects with water heaters, coffee machines, purifiers & more via standard G1/4 thread. - • **Plug & Play Installation:** Lightweight, compact design with secure sealing ring eliminates leaks and simplifies setup. ## Overview The GREDIA 1/2" Water Flow Sensor is a high-precision hall effect flowmeter designed for fluid rates between 1-30L/min, operating safely under 1.75Mpa pressure and 0-100°C temperature. Made from food-grade, ROHS-certified plastic, it fits standard G1/4 inch male threads and supports DC 5-24V input. Ideal for professional-grade water heaters, coffee machines, purifiers, and beverage systems, this dual-pack offers reliable, leak-proof installation with ±2% accuracy, empowering millennial managers to optimize smart fluid control effortlessly. ## Description Our products are fine made with nice materials and good workmanship, strict quality control, guarantee in after service. The flowmeter is light and handy, easy to install. The sealing ring make the connection firm, the sealing performance is good and the problem of water leakage is avoided. More details about the flow meter: F=（7.5*Q）±2%, Q=L/Min, error: ±2% Working range: 1-30L/min Working voltage: DC 5-24 V Water Pressure: ≤1.75Mpa Liquid temperature: 0-100℃ Maximum current consumption: 15 mA(DC 5V) Wire length: 15 cm Size: 62mm x 36mm x 36mm(L*W*H) Refer to the wiring: Red wire: VCC(+) Black wire: GND(-) Yellow wire: Signal output Package: 2 x G1/4 inch flowmeter Review: Using with a reef aquarium to control flow thru a UV sterilizer - 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. Review: Works great on my laser cutter - Great replacement for the flow sensor on my Red China laser. ## Features - Connect to G1/4 inch male thread, hall effect, comes with 2 pieces - Flow range:1-30L/min, Water Pressure: ≤1.75Mpa - Working voltage: DC 5-24 V, F=（7.5*Q）±2%, Q=L/Min - Material: food grade plastic, all raw materials conform to the ROHS test standard - Wide application: It is mainly used in water heater, coffee machine, water purifier, drinking fountain, beverage machine, campus smart card equipment, etc. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B07RG4KXWJ | | Best Sellers Rank | #36,607 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #13 in Flowmeters | | Date First Available | May 2, 2019 | | Item Weight | 3.52 ounces | | Item model number | GR-201P2 | | Manufacturer | GREDIA | | Package Dimensions | 7.13 x 4.61 x 1.38 inches | ## Images ![1/2" Water Flow Sensor Food-Grade Switch Hall Effect Flowmeter Fluid Meter Counter 1-30L/min (Pack of 2） - Image 1](https://m.media-amazon.com/images/I/61nLiOnDsJL.jpg) ## Available Options This product comes in different **Size** options. ## Questions & Answers **Q: If the output signal is a pulse, what is the pulse rate per liter and duration per pulse?** A: The current image shows an "F" number of 7, which means 7Hz per liter/min, so 7 pulses per second indicates a flow rate of 1 liter/minute, hence 7 * 60 seconds/minute = 420 pulses per liter (per minute). I have no idea what the duration would be. **Q: Does it prevent back flow or what happens if water does try to go in wrong direction?** A: It does not have any backflow prevention. It is a little water wheel inside a pipe which has magnets in the vanes of the water wheel. The unit simply counts magnetic pulses as the wheel is moved by the water flow. It would probably register water flow either way but would only be accurate in the forward flow direction. Any domestic water system should have backflow preventers in place to keep drinking water contamination from occuring. **Q: Are the threads npt, bspt or bspp? please understand this is basic info should always be provided without having to specifically ask. thanks.** A: Hello, thank you for your inquiry. It's BSPT. **Q: If the flow rate is less than 1L/minute, will it not not show any pulses? I'm interested in using this to detect leaks and 1L/min is a lot of water.** A: I don't know about 1L/min, but I have tried pumping liquid through one using a dosing pump and nothing registered. The water wheel will have some resistance, so a very slow flow might not register. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Using with a reef aquarium to control flow thru a UV sterilizer *by B***. on June 26, 2023* 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. ### ⭐⭐⭐⭐⭐ Works great on my laser cutter *by S***T on December 12, 2025* Great replacement for the flow sensor on my Red China laser. ### ⭐⭐⭐⭐ Not perfect but for the price i have no complaints *by A***R on December 30, 2023* 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() ## Frequently Bought Together - GREDIA 1/2" Water Flow Sensor Food-Grade Switch Hall Effect Flowmeter Fluid Meter Counter 1-30L/min (Pack of 2） - Ximimark 2Pcs 1/2" Thread Plastic Electric Solenoid Valve Water Inlet Flow Switch Magnetic Water Air Normally Closed Tools DC 12V N/C 0.02 to 0.8mpa - GREDIA 1/2" DC 12V Solenoid Valve N/C Normally Closed Water Inlet Flow Switch --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.pl/products/143719307-1-2-water-flow-sensor-food-grade-switch-hall-effect](https://www.desertcart.pl/products/143719307-1-2-water-flow-sensor-food-grade-switch-hall-effect) --- *Product available on Desertcart Poland* *Store origin: PL* *Last updated: 2026-04-23*