using oxygen flowmeter with argon

admin

Hey everyone, I'm trying to use a gravity/ball-type flow meter that is labelled for use as an oxygen flow meter, with argon. I was wondering if the values given on the flow scale are correct when using argon (which has a different molecular weight and density than oxygen)? My question comes down to this: does an argon flowmeter need to made specifically for argon, or can any gravity/ball flowmeter be used with any gas?
Reply:The mechanics are the same, but the scale on the sight glass will be incorrect.
Reply:It's an old thread but... since I am doing the same thing , I wanted to complete this.The correction factors you need are on this web site.http://mpbflowmeters.com/downloads/M...onversions.pdfAir = 1Nitrogen = 1 / 0.98= 1.02Oxygen = 1 /  1.05 = 0.952Argon = 1 / 1.18 = 0.8475Helium = 1 / 0.37 = 2.70These numbers apply to flow rates measured with a floating-ball type flow meter, not an orifice-type flow meter.So for a floating ball type gas flow meter...Imagine you had water in the flow-meter tube but no flow, the ball would likely float to the top because the density of the water is higher than that of the ball.Thus, it logically follows that a fixed flow rate, a denser gas in the tube will push the ball up higher.e.g. Oxygen density = 1.105 and Argon density = 1.38Thus with the same flow rate of each gas, argon's higher density will push the ball higher - indicating a higher apparent flow rate than oxygen.The correction factor Air to Oxygen is 1/1.05 = 0.952.i.e. 0.952 unit volume flow rate of oxygen will raise the ball to the same height as 1.0 unit volume flow of air.The correction factor Air to Argon is 1/1.18 = 0.8475i.e. 0.8475 unit volume flow rate of argon will raise the ball to the same height as 1.0 unit volume flow of air.Thus a floating ball meter calibrated for oxygen, when fed with the same flow rate of argon, with show an apparently higher flow rate of 0.952/0.8475 = 1.123.The other way to think of this is that you have to reduce the argon flow rate by 0.8475/0.962 = 0.89X for the graduations on the oxygen flow meter to read correctly for argon.Here's a real example.e.g.  My medical oxygen flow meter reads 0 to 15 liters per minute.Conversion Factor: 1 liter/minute = 2.12 cubic feet per hourThus my flow meter reads 0 to 15 x 2.12 or 0 to 31.8 cubic feet per hour.However, now I need to correct for the fact that I have changed from oxygen to argon gas.The 0 to 31.8 cubic feet per hour becomes 0 to 0.89 x 31.8 = 0 to 28.3 cubic feet per hour.If you just want to have a good idea for welding purposes, then as a rule of thumb 0 to 15 liters/minute oxygen bcomes 0 to ~30 cubic feet per hour of argon.There - put that baby to bed! Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:You'll have to change the fitting.  I would just order a new one from HTP and get on with welding.