Pico Flow meters

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Pico Flow meters

Post by ben.martins »

Some of you may or may not be aware but to go alongside our hydraulic pressure transducer, WPS600C, we can also supply our customers with a flowmeter. We have chosen a bespoke flow meter range from Webtec that allows us to graph flow readings in PicoScope along with other signals. These include a 25lpm, 300lpm and 600lpm turbine flow meter. The 300 and 600 come with a loading valve in order to load a hydraulic circuit or pump for diagnosis.

Lately we have had a few requests about how to correctly set the flow meters up with PicoScope and so I've put together a small user guide. In no way can should this be used as a training guide in terms of the connections being made to machine. If you've never fitted a flow meter to a circuit then please don't use this as a how to guide. I'm purely going through what you have to do in order to connect the flow meter to the scope and then configuring the software to read flow measurements.

Please remember this tool, along with many Pico products is intended to be used by qualified personal only. Hydraulics is not something to be having a go at.
Unpacking the flow meter please take care that the caps are still present to prevent any contamination entering the unit. Please also take note of the instructions supplied with the flow meter as these will provide you with detailed information in how connecting the flow meter and additional items such as the burst discs.
Next, we need to make a note of the ‘K’ factor which will be on the plate mounted on the front of the meter. This will be preceded by the letters ‘PPL’ which will need to be input into PicoScope when we are ready to measure. In the example below the ‘K’ factor is 132.70.
300lpm K Factor.png
From here you will now need to connect the flow meter into the circuit. You will be required to use the correct PPE, training, knowledge and experience whilst ensuring that any potential contamination concerns can be kept to an absolute minimum in order to connect safely and securely. You may find that the adapters will be required to step up or down to connect the flow meter and having these to hand. Adapters and connectors can be sourced from all good hydraulic suppliers. Additional pipes will be required to extend the existing pipework and these pipes should be as clean as possible; a pellet gun is a good idea to keep contamination to a minimum.

Both the 300 lpm and 600 lpm flow meters come equipped with a loading valve; please ensure this is in the fully open position before starting the machine to prevent excessive high pressure being allowed to build in the meter.

Tech Tip - It may be worth noting here that if you do not know the condition of the oil from the machine you are testing then a flow meter might not be the best option. There is a possibility of contaminating your flowmeter and then passing that onto the next machine.

Safety discs are built into the 300lpm and 600 lpm flow meters that will burst if significant pressure does build. This will bypass the loading valve and allow flow to pass through the meter safely. The discs can be replaced with new ones which can be purchased direct from Webtec. A list of accessory and part numbers can be found within the product guide included in your kit.

With the flow meter now in circuit, connections are secure and the loading valve open (if applicable) take one of the BNC to BNC leads and connect the flow meter to a channel on the PicoScope and the ‘Q’ connection on the top of the meter and finish by connecting your PicoScope to your PC with the USB cable. Please bear in mind the flow meters are designed only to be used with PicoScope 4423, 4X25 and 4X25A. The flowmeter settings require frequency counting which is only available on these models.

Temperature measurements can be made by using the TA370 adapter. If using the TA370 for the first time a CR2032, 3V battery, is required. Please note that when finished with the TA370 ensure to remove the 3.5mm connector as leaving it connected will keep the device powered on and flatten the 3V battery. Connect the BNC from the TA370 to a channel, typically Channel B if measuring flow on Channel A, on PicoScope and then using the additional BNC to BNC cable, connect one end to the ‘T’ on the flowmeter and the TA372, 3.5mm jack adapter, into the TA370.
flowmeter connection drawing.png
With the hardware connections now complete and your PicoScope connected to a USB port on the laptop/PC, open the PicoScope 7 Automotive software. Ensure you have the latest software version which can be checked by clicking More > About PicoScope 7 > Check for updates.
PS7 Updates.png
If still using PicoScope 6 Automotive Software. Please ensure you have a software version of or higher. If you’re unsure of how to check your version click Help > About PicoScope 6 Automotive Software. This will open a new dialog box with all the information including the software version.
PS6 SW Version.png
If this is not the case please visit www.picoauto.com/downloads to install the latest version.

Tech Tip – Flow meter probes only appear as a probe when you have a compatible scope connected.
PS7 flow meter selection.png
To select a flow meter, you will need to click the box of the channel input you have connected your flow meter too, A, B, C or D. Then select the Probe tab and then locate the Flow meter probe. You’ll then see the 3 flow meter options. Select the flow meter you have connected to your scope. You will now notice that underneath the selected probe there is the ‘K’ Factor input.
PS7 k factor.png
This will be the number from the front of the flow meter denoted by PPL that we saw earlier. Once this has been input the software will automatically adjust the scaling. If using PS6 once you’ve entered the ‘K’ factor you will not be able to edit it till the next day so please ensure you’ve checked before hitting OK. You will now see that the axis units have changed to LPM and the whole range is present.

To add the temperature probe, select the channel you have attached the TA370 too and then click the probes tab. Here you will find the TA370. Please select this from the list and then click on the Vertical tab to select the range.
PS7 TA370.png
This is all that is required to setup the software and unless you wish to alter the time base nothing else need to be altered. For a general time base I would look at maybe 5s/div as this gives you 50 seconds across the screen. This allows you to see the flow change as you operate a service or use the loading valve. Start the machine and check for any leaks or kinking of pipework. If any found stop the machine immediately and repair connection before restarting. Never attempt to fix leaks with machine running.

To broaden your measurements, you have the option to connect a pressure transducer to the flow meter via the 1620 Minimess connector. This could be a gauge just to monitor the pressure or if you have a WPS600C then you can include this in your capture. This will allow you to carry out additional features with math to calculate pump performance. The following forum post will help with this setup. viewtopic.php?p=98250#p98250

When it comes to disconnection always switch the machine off and allow for a few minutes for the pressures to settle. Also, please allow for the temperature to drop if the system has been loaded as the oil will now be hot. Disconnect all electrical connections first as there will inevitably be some oil spillage when removing the hoses from the flow meter. If a significant amount of oil is lost ensure the machine is topped up with the correct grade and specification of oil and remember to filter the oil as it is poured into the tank.

To summarize -
  • Connect flow meter into system observing safety and contamination concerns ensuring load control valve is in the open position
  • Take note of ‘K’ factor – number after PPL on plate fixed to meter
  • Connect BNC lead to ‘Q’ connector on meter to a PicoScope channel
  • Connect BNC lead to ‘T’ connector on meter & to the TA372 adapter and then to the TA370 to record temperature
  • Connect PicoScope to PC USB port
  • Start PicoScope 7 Automotive software. If using PicoScope 6 Automotive software ensure version is above
  • Select flow meter from the probe tab in the channel options
  • Input ‘K’ factor when selecting the probe from the menu
  • Select TA370 from Automotive Probes in channel settings to measure temperature and ensure a battery is present
  • Click the Stopped button in the top left-hand corner or press space bar to begin capturing
  • Start machine and check for leaks
  • Always repair any leaks with machine switched OFF and ensure no pressure is present
  • Run the machine, carry out the test & save the capture.
I hope this helps and please again, don't use this as a guide to working on hydraulics. Our hydraulic products are designed to be used within the correct industries and any adaptations or using the products outside of their intended use could cause damage and more importantly injury to you or others.

Be sensible and be safe.

Kind regards


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