Flow Sensor

Top Selected Products and Reviews

"Specified calibration seems to be off, but otherwise works as well as stated (2% accuracy)" - by alexw
Only 2% accurate, but the calibration factor specified as 7.5hz/(l/min)=450pulses/liter seems to be quite off as well. After averaging a couple of tests, I've calculated it to be more like 13.25hz/(l/min) = 796 pulses/liter.
"I have an eco 11 which was leaking. My ..." - by Amazon Customer
I have an eco 11 which was leaking. My original part was metal and had 2 screws for 2 other sensors. This one is plastic and didn't have any screw hole for the extra sensors. Luckily, I could use the o rings and the spinning part with the magnet and the sensor from the new replacement.
"Easy replacement for flow switch" - by Claudia1
I bought this flow switch as a replacement to one that had failed with my Hayward saltwater chlorinator. While I'm disappointed in the design that Hayward chose because the original failed after only two years, this replacement switch worked perfectly. It was easy to install, including the wire that goes to the box having a couple of helpful features. First, the wire that goes to the main box was offset towards the side of the flow switch where the direction of flow goes, meaning that in my case doing an upside-down install without being able to see the arrows was easy to tell which direction was the right way. There were also two slightly raised arrows in the plastic to help line this up in the direction of flow. Second, the other end of the wire had a telephone line attachment that made it easy ... full review
"Works fine but restricts the flow" - by WayneH
Excellent for the price, but it it has its limitations. As other reviewers wrote, it restricts the flow. I wouldn't want to use it if a water line larger than 1/2 inch is needed. Calibration appears to be within about 5% from 0.5 gpm to 4 gpm. Below 0.5 gpm calibration falls off quickly. I showed an 18% error at 0.38 gpm. I didn't test it above 4.28 gpm which is all I got through my 1/2" hose.
"The flow sensor that was factory installed developed an internal ..." - by Kindle Customer
The flow sensor that was factory installed developed an internal leak, causing the sensor to fail. Installed the new sensor and water heater works perfectly. Hopefully this isn't an ongoing thing.

Pic is of the old part, complete with corrosion.
"Great for monitoring aquarium filter flow" - by Brandon
I am very impressed with this flow sensor. I purchased two to be used on my African Cichlid aquarium. I have two canister filters--and I didn't notice that my flow was significantly reduced before I went on vacation during the 4th of July weekend. Came back to several dead fish... :(

I am using this with a Particle Photon combined with the Blynk app to remotely monitor the flow and alert me if the flow is below a threshold.

I found barbed tube (5/8") fittings on McMaster, part # 5372K218.

The sensors have a 3 pin JST connector (available on Amazon).
"The FL-S402B flow meter is pretty amazing! The quick connects snap right onto 1/4" ..." - by Margaret Marystone (Chicago, IL United States)
The FL-S402B flow meter is pretty amazing! The quick connects snap right onto 1/4" ID plastic tubing for easy setup. I connected this to my Raspberry Pi and my Reverse Osmosis system with ease. This unit appears to be much more sensitive than FS200A G1/2 meter I had been using, but I will have to do more testing to see how accurate it is. It should deliver 1,380 pulses per Liter, according to data I found online. I'll try to update this review when I learn more about the accuracy.

The plastic locking clips are very difficult to remove, I'm guessing because of the extra sturdy plastic. When I tried to remove them by the tab I just broke the tab right off. I suggest pressing needle nose pliers against the two ends of the clip firmly to pop them off (they will go ... full review
"Great flow sensor at unbeatable price!" - by WayneH
Bought this to measure the flow rate from my 10GPM submersible pump which lets me calculate how many gallons I have in reserve in my 350' well. I first bought the 1" model, but it is different design and is very constricted. This one has negligible pressure drop even at high flow rates. I'm running it at 5V and making pulse decisions at 1V. The label indicates the pulse train frequency is 0.5 Hz * flow rate in liters/minute which matches what I get measuring the water quantity. The thread isn't an exact NPT, but threads and seals fine using Sch 40 PVC fittings and liquid thread dope with Teflon. I measure the pulse interval to 100uS resolution to get flow rate and count pulses to measure water quantity. The results look perfect using a $10 Cypress PSoC CY8CKIT-059. Try it - ... full review
"This was a pretty easy replacement as it only took about 20 minutes ..." - by Juan Limon
Direct replacement mass airflow sensor for a 1999 Chevy Silverado 1500 with a 5.3l engine. This was a pretty easy replacement as it only took about 20 minutes to remove the old sensor and replace it with the new one. The truck runs much smoother with the new sensor and it idles much better also. It is also much more competitively priced than at the local parts stores.
"The tube size a bit vague and for that reason ..." - by Luis another Amazon Customer
The tube size a bit vague and for that reason i ordered this product, which was the wrong one for the job. That been said, i used the product for another task and works flawlesly.
"At first I thought it was crap... I was wrong it's nice" - by Amazon Customer
At first I thought it was fake. I guess I expected it to output a voltage based on the flow (less voltage for slow, more for fast) but I put it on my oscilloscope and saw that it was pulses and the frequency was based on the flow. I used the FreqMeasure library written by Paul Stoffregen and I took the frequency obtained and multiplied it by 0.0117951447 (obtained experimentally) to get liters per minute
"Get those home-brew volumes precise. Bundle this with the power supply, flow sensor, and solenoid." - by Splash Trailhead
Using this in my home-brew setup to measure the exact amount added to the mash tun and then shutoff using the Digiten 1/2" DC12V normally closed solenoid. Remember to buy the Digiten power supply (required, not included) unless you want to rewire the DC24V +-8V/1A connector. Works exactly as expected, right out of the box. I found the default "K" constant a bit high for my 1/2" silicon tubing and the instructions make reasonably clear sense about changing it (go to that screen, enter the password, then you can change "K") - in my case, changing it from 7.5lpm to 6.5 was about right. Attaching the instruction sheet because it is difficult to find elsewhere.