Sika Flow Sensors           - Page 1
Forum section: electronics / projects

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 02, 2025, 11:00:09 am
content: Hi Guys,I'm trying to understand this Sika Flow Meter that I have.Here is the PDF to download:https://www.sika.net/fileadmin/products/corporate/datasheet/vortex_flow_sensors/Datasheet_vortex_flow_sensors_VVX15_VVX20_VVX25_EN.pdfIt is installed in a Heat Pump and visualizes (in m³/h) the flow and the program also checks the flow in case it drops below 0,7m³/h and gives a warning/error and the heat pump stops or does not start.In my system I always have more flow than necessary. Now it is nice that it can display the flow but I do not want it to shut down my system in case it acts up or breaks? So I want to know how to tell the controls it is all good, you know just give it a value bigger than the min of 0,7m³/h.I just would like to understand the circuitry behind it.I attached a picture of which model/connection I have (NPN open collector).So as far as I understand it at the moment the Flow Sensor gives my CPU a PWM signal and the program displays it and also checks it if the minimum is met?There are 3 Wires coming out of the Sensor: brown, blue and blackBetween (br-bl that would be 1+3) I have 5VDCAnd between (bl-blck that should be 3+4) I have about 2,5VDC in standby and when there is flow it is about 1,2VDC and minimally changing.Thanks for the help in advance.

author: mikerj
author_rank: Super Contributor
timestamp: February 02, 2025, 11:59:14 am
content: How are you going to differentiate between a flow sensor fault and a genuine low flow situation?

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 02, 2025, 03:53:16 pm
content: Quote from: mikerj on February 02, 2025, 11:59:14 amThat is not the topic. Thanks

author: Martinn
author_rank: Frequent Contributor
timestamp: February 02, 2025, 05:41:04 pm
content: Explanation of sensor principle... interesting! Never heard of that. Certainly there will be a patent for this.

author: Poroit
author_rank: Frequent Contributor
timestamp: February 03, 2025, 04:40:22 am
content: G'day blauerscharik,The datasheet states that there are four different outputs available:• Frequency output• Analogue 0.5...3.5 V and frequency output• Analogue 0...10 V or 4...20 mA and frequency output• Frequency output with IO-LinkI suggest yours is;Frequency signal, square wave, pulse duty ratio 50:50, signal current max. 20 mA Push Pull or NPN open collector.Can you see an areas in the Controller Setup Program that has a Scaling factor for the flowmeter pulses?

author: mikerj
author_rank: Super Contributor
timestamp: February 03, 2025, 12:47:10 pm
content: Quote from: blauerscharik on February 02, 2025, 03:53:16 pmAKA you aren't going to bother

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 03, 2025, 06:20:12 pm
content: Quote from: Poroit on February 03, 2025, 04:40:22 amHi there,sorry I haven't realized that the picture wasn't uploaded.I have the NPN open collector sensor with square wave.Yes there is a scaling option and it is set to 200.

author: Poroit
author_rank: Frequent Contributor
timestamp: February 04, 2025, 06:31:39 am
content: Quote from: blauerscharik on February 02, 2025, 11:00:09 amIs the following correct?Because you have a high Actual Flowrate, you want to change the Low Flow Setpoint to a higher value than 0.7.

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 04, 2025, 12:49:40 pm
content: Quote from: Poroit on February 04, 2025, 06:31:39 amNot quite. I want the CPU to think I have a flow rate higher than 0.7, even if I have less.

author: Poroit
author_rank: Frequent Contributor
timestamp: February 05, 2025, 04:15:02 am
content: Send us a link to the Controller manual.Are there separate areas in the controller program to calibrate the Actual Flowrate and the Low Flow Setpoint?Is there also a standalone Flow Switch in your Heat Pump?

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 05, 2025, 03:07:33 pm
content: I don't think it's gonna help you, you are not going to change anything in the programming.You are thinking about software, I am talking about hardware -> electronicsWhat I need explained is how this NPN open collector works, and how to bypass it.

author: Poroit
author_rank: Frequent Contributor
timestamp: February 06, 2025, 09:28:10 am
content: OK.Google, How Do NPN Open Collector Outputs Work and you will find numerous explanations and videos.Hmm.......Are you looking for a Pulse Splitter so you can retain the existing Controller and have a separate output to another controller to shut down the Heat Pump if the SIKA Sensor fails?

author: Marco
author_rank: Super Contributor
timestamp: February 06, 2025, 07:33:35 pm
content: Quote from: blauerscharik on February 02, 2025, 11:00:09 amSince it's frequency output, the most reasonable solution is a microcontroller ... which is probably not a very reasonable solution.

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 08, 2025, 08:03:30 am
content: Quote from: Poroit on February 06, 2025, 09:28:10 amOk thanks.No, I wan't to remove it altogether. I have other safety measures in place which will shut the system down.

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 08, 2025, 08:11:10 am
content: Quote from: Marco on February 06, 2025, 07:33:35 pmDefinitely unreasonable. But I don't like that it could potentially shut down my system...So is this how it works:The waves of the water make the pulses, the piezoelectric element bends and creates electricity and that is amplified/switched by the NPN open collector and the system is receiving a PWM Signal?Would that be correct?

author: benseno
author_rank: Regular Contributor
timestamp: February 08, 2025, 08:31:41 am
content: So, you want pwm out of sensor not to fall shorter than specific value?It can be done by 555 (single pulse mode) circuit that whose cycle starts with rising edge of pwm from your sensors and whose output is ore'd with pwm from sensor. The pulse length of 555 should be the minimum pwm duty that fulfills your need.

author: Poroit
author_rank: Frequent Contributor
timestamp: February 09, 2025, 08:44:33 am
content: So is this how it works:The waves of the water make the pulses, the piezoelectric element bends and creates electricity and that is amplified/switched by the NPN open collector and the system is receiving a PWM Signal?Would that be correct?Yes

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 09, 2025, 12:45:07 pm
content: Thanks.I was thinking about the 555 timer. Guess I will have to try that.

author: Poroit
author_rank: Frequent Contributor
timestamp: February 10, 2025, 04:21:09 am
content: I guess you want to build your own but here is a link which shows the sort of instruments that are available to interface with your Sika.https://defineinstruments.com/shop/panel-meters-indicators/pro-flo200-flow-batching-totalizer/Good luck with your project.

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 10, 2025, 05:41:19 pm
content: Quote from: Poroit on February 10, 2025, 04:21:09 amThat's good info. Thanks a bunch.

author: Marco
author_rank: Super Contributor
timestamp: February 11, 2025, 09:48:52 am
content: Quote from: benseno on February 08, 2025, 08:31:41 amIf the sensor flatlines the monostable output will flatline too.If he used a multivibrator it would need be an oscillator with an edge triggered reset (a proper reset, which also resets the timing capacitor). But it would create glitchy output when the input frequency is an integer fraction of the limit frequency.If you really wanted to do it without a micro, you could do F->V->limit->F. With frequency to voltage and voltage to frequency converters.

author: blauerscharik
author_rank: Regular Contributor
timestamp: February 16, 2025, 12:12:44 pm
content: QuoteWhat exactly do you mean by that?