Ideas please, how to measure 50 to 150 lpm at 8 to 10 bar

[AdrianH]

This is to be placed in my 10mm airline so standard fixings if possible, I would like to measure the flow rate my air plasma is taking.

Most gauges I see are a lot lower flow rates, not sure what is out there, anyone any ideas?

Adrian

 

[Kayos]

I’ve seen turbine inline gauges that will read that, they come with 2” flanges and cost about £900......

 

[Hood]

Not really what you are asking but if just needing one off measurements for adjusting then a peashooter style flow meter can be held over the torch end to measure the flow.
Got one with my Trafimet machine torch, no readings on it though, just a cross and circle to show where the flow should be but maybe you can get graduated ones.

 

[Hood]

This is the type I mean, I wonder if you can get graduated ones? Will see if I can find anything.
https://www.ebay.co.uk/itm/CV0085-F...t-ERGOCUT-S45-HY40-Plasma-Torch-/400717978385

 

[Hood]

Here are some, not sure max pressure they can take, also not the cheapest but looks like they can be fitted inline.
https://www.coleparmer.co.uk/i/cole-parmer-acrylic-flowmeter-100-mm-scale-for-air-10-100-lpm/3245860

 

[GW8IZR]

For such a test just tape / hold a black bin liner over the torch end, pull the trigger and wait for it to be full... you can easily calculate the volume and measure the time.

 

[waddycall]

For such a test just tape / hold a black bin liner over the torch end, pull the trigger and wait for it to be full... you can easily calculate the volume and measure the time.

Or put a hose on the end of the torch and put it in to an upturned vessel full of water in a bucket or tank and see how long it takes to displace the water.

 

[AdrianH]

The measurement is my way of trying to figure what the hell goes wrong at times when cutting i can fit a new consumable and suddenly i can no longer cut metal, the nozzle is 1mm and a few calcs say it should pass approx 27 lpm at about 63 psi, so that means around 60 lpm is going passed it from the shroud, (90 lpm total).

the quality of the parts is quite abysmal, I have 4 different style tips for the same torch, they are meant to do the same job, but all have differences in one way or another, so I really want to figure things out, so a quick reading as I try things out is what I am after.

Long term I have ordered a different torch, but will take some time to get to me. I was hoping to place something in the main line as an indicator, yes I have seen some of the prices for proper measurement gear and we are into a lot of money at times. I have even considered a MAF unit from a car and a bit of electricery, but I doubt I could seal the MAF sensor at at line pressure 8 bar.

Adrian

 

[Hood]

My torch is supposed to be set to 4Bar and it is supposed to pass 100LPM and that is a 1mm nozzle.
Air also comes out of the shroud through holes, maybe yours is the same?

 

[AdrianH]

Yes it will be similar, on the cheap PT31 torch most of the air flow is in the shroud and I tend to think I loose the air flow through the nozzle due to bad fitting parts, the tip and the shroud seem to be the parts that can vary the most.

Adrian

 

[dannyp]

you chould put say a pressure reg in the line, set at ay 100 psi then a restrictor in the line and measure the pressure drop across it, before the air goes to the reg on your plasma.

at constant pressure through a given size hole pressure across the hole should be directly relatable to flow i bet theer is a tabel for it on the internet somwhere

 

[AdrianH]

A bit of Bernoulli theorem? Without restricting the air flow not sure if i would see enough of a drop, but I will play with the calculator.

It's a pity as most of the manometer ones I see (digital) have a max pressure of around 10 psi and not 8 to 10 bar.

Adrian

 

[optima21]

another possibility is to look at pitot tube flowmeters

http://www.dwyer-inst.com/Products/AirVelocityIntroduction.cfm

I know they can be used with low pressure flow rates for flowbenches, but a quick google shows they can be used upto 150psi.

I once made a pitot tube to measure airflow while porting an engine, using 1/16 and 1/8 aluminium tubing off ebay

for a home made one, calibration may not be too easy though

 

[dannyp]

A bit of Bernoulli theorem? Without restricting the air flow not sure if i would see enough of a drop, but I will play with the calculator.

It's a pity as most of the manometer ones I see (digital) have a max pressure of around 10 psi and not 8 to 10 bar.

Adrian

would just play around with the hole size you chould have say a 2mm hole and drop the pressure 20 psi across it would be ideal. a the plasma is regulating it down to 60 odd psi it woldnt even notice it as it running its own pressure regulator

 

[optima21]

juts thinking about this again, with flowmeters, you can measure flow with an orifice plate

but the maths is way beyond me, so I didnt use this method to measure flow

https://www.omega.co.uk/literature/transactions/volume4/orifice-plate.html

this link may give you some other ideas too

https://www.engineeringtoolbox.com/flow-meters-d_493.html#Orifice_Plate