Looking for a Pressure gauge and flowmeter

[JulesP]

Hi there,

I’m looking for a pressure gauge and flow meter to use with a low pressure brazing system using OxyHydrogen gas generated by an Electrolyser.

The pressure in the gas generator will be less than 20psi and the flow rate no more than 7l/min.

Can you suggest any device/meter such as used for shielding gas? eBay do some regulator and flow meters that might be ok for use with CO2?

Thanks

Jules

 

[Turbo]

You will need to use equipment rated for oxygen use as it has oil free internals. (Oxygen under pressure + oil = explosion!)

 

[timgunn1962]

Are we talking a Stoichiometric mixture of Hydrogen And Oxygen generated by electrolysis of water without separation of the Hydrogen and Oxygen?

I'm not familiar with OxyHydrogen (aka Browns Gas or HHO) and to be honest the very concept makes my bottom twitch. There are too many obviously dangerous cranks messing with it to give me any confidence in readily finding good information online.

The OP is asking a couple of pretty basic questions on their first post here and the probability seems quite high that they are one of the aforementioned dangerous cranks. I am therefore not going to make any suggestions in respect of gauges.

Assuming one has done their research and has the safety issues covered to their satisfaction, sorting out a working flowmeter can be regarded as a simple exercise involving only the physical properties of the gas.

The usual welding flowmeters are "rotameters": variable-area flowmeters that use a ball in a tapered tube. They are calibrated for gas of a given Specific Gravity, pressure and temperature. Assuming the temperature and pressure of the OxyHydrogen will be pretty close to the temperature for which the flowmeter was designed, the only correction that is needed is for the Specific Gravity, which is proportional to the Relative Molecular Mass of the gas.

https://www.brooksinstrument.com/en...-my-variable-area-flow-meter-for-a-gas-with-a

The formula looks pretty scary, but the P part in the brackets and the T part in the brackets are both 1 if Pressure and Temperature are the same, so the correction factor is "just" the square root of the SGscale/SGnew.

OxyHydrogen is electrolysed water (H2O), so the gas mixture is 2 parts Hydrogen (H2) to 1 part Oxygen (O2)

The RMM of Hydrogen is 2

The RMM of Oxygen is 32

The RMM of the mixture is (32 + (2 x 2))/3 = 36/3 =12

The RMM of Argon is 40, so correction factor for an Argon rotameter is sqrt(40/12) = sqrt(3.333) = 1.82

The RMM of CO2 is 44, so correction factor for a CO2 rotameter is sqrt(44/12) = sqrt(3.666) = 1.915

The RMM of Air is 29, so correction factor for an Air rotameter is sqrt(29/12) = sqrt(2.417) = 1.55

It is worth noting that, if you have any unusual gas of known composition, you can get an off-the-shelf Rotameter and either work the correction factor out by doing the multiplication each time, or spend 10 minutes doing it once and rescaling it with a pen and a sticky label.

 

[JulesP]

Thanks that’s very helpful. So in the case of a meter set for CO2, I multiply the reading by 1.915 to get the HHO flow? (Not divide)

HHO has valuable properties for welding in that it has a modest flame temperature around 160 C but yet can vaporise Tungsten due to the highly energised state of the gas - but that’s another story.

 

[Seadog]

HHO has valuable properties for welding in that it has a modest flame temperature around 160 C

Are you sure?

 

[JulesP]

So I should be able to use something like this with a factor:

 

[JulesP]

Are you sure?

Yes it’s about 130 degrees (see attached paper) but the flame adapts to the melting point of the substance being worked on so can melt Tungsten without problem.

 

[daleyd]

Yes it’s about 130 degrees (see attached paper) but the flame adapts to the melting point of the substance being worked on so can melt Tungsten without problem.

Your basing your theory that it burns at 130 deg on one research paper? Do you know if this paper has been reviewed and the conclusions verified, especially as most other sources would indicate that it’s got a flame temperature in the thousands of degrees?

 

[JulesP]

It’s based on the experience of many who have used HHO welding for years. Not every truth in the world has to be subjected to repetitive testing to validate what is already known. If you need that in this instance then you will need to go to the trouble of testing and confirming or denying it yourself.

Yes it can melt metals at over 3000 degrees but that is because the high energy of the particles that make up the flame is released according to the atomic makeup of the metal being worked on. Anyway I’m not here to get into such a debate.

 

[daleyd]

Well, you should be able to back up claims that you make, since it was you that brought them up initially.

I think it’s well known it’s been used in jewellery manufacture for years, and for things like that it has its place, obviously otherwise they would be using other methods. But for general welding of steel I think it’s pretty much been kicked into touch due to causing hydrogen embrittlement.

Fair play though, hopefully whatever application you have in mind works out - it’s be good to see some results from whatever you do.