Managing gas usage

I’ve done some poking around today wrt managing gas usage, and I think I’ve come up with a reasonable idea?

You can buy ‘mass flow controllers’ which are are a mass gas flow sensor + valve. They get super expensive if you blink but new ones can be had for ‘reasonable’ prices. This one is 0-10L/m, good operating range, valve leak rate is exceptionally low (Helium leaks at 5mL a year), provides both flow output and flow control input on a 5vdc analog. So you could throw a gas bottle in a cage, plumb this onto it, open the bottle valve and leave it open and let the MFC do the work.

You can also find them secondhand commonly: https://www.ebay.com/b/20-SCCM-Maximum-Flow-Rate-Mass-Flow-Controllers/184061/bn_87945361?rt=nc&_sop=15 but it can be hard to find the datasheet or manual for them.

I think this is kind of a one-stop-shop to solve gas metering and control. with a basic micro to control the MFC you can both meter and control output. Considering what we spend on gas this would let us manage and recoup excessive use.

Thoughts?

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Let’s do it. Let’s do it now.

My brain got back into this this evening since the conversation has come up again, so just dropping some links for later reference:

Any mass flow meter would need to support 10SLM, or 10LPM, or 10,000SCCM. (ie 0-10L per min).

Getting one calibrated for argon makes most sense, but not sure how far off the numbers would be if you got one calibrated for something else.

Aera transformer models can be found on ebay for around $250USD ish. theres an analog and digital devicenet version, devicenet is plc canbus magic. theres on online example of someone talking this protocol with arduino.

You can find a bunch of UNIT brand ones, such as UNIT UNC-1100. These have an analog card edge, but they are all from the 80’s, who knows how good they are. Can be found under $100.

DigitalNet version

Analog version

Aera_transformer.ind

Open Control Systems and DeviceNet Applications

Since mass flow controllers are about double the cost of mass flow meters, perhaps a better idea is a separate valve:

SMC VEF3120-3-03 vef base mt 3/8, VEF PROPORTIONAL VALVE
https://www.smcpneumatics.com/VEF3120-3-03.html

14_9_VBA_VE.qxd
https://www.smcpneumatics.com/pdfs/VEP.pdf

welding gas has a high and low pressure side, it may be useful to track these because they may be more indicative of a slow leak than the mass flow meter, as the mass flow meter tends to have a floor where it loses accuracy.

1/8" NPT 5V Stainless Steel Pressure Transducer Sender Sensor Fuel Air Gas AU | eBay

2000 PSI Honeywell Pressure Sensor

IFM EFECTOR Pressure sensor 4 Digit Analog Out – 0…250Bar Range – PN2021 | eBay