I thought I would make a post to clear up the compatibility issues with brass and methanol which is commonly used in a 50/50 mixture in an alcohol injection kit. This is something we ran across well over a year ago. Just finally getting around to putting it down for others to use.

Brass, while considered chemically compatible with methanol and water by themselves, can have a chemical reaction with the methanol/water mixture when used in an alcohol injection system. The chemical reaction happens when the methanol/water mixture combines with the air bubbles and travels threw the system. This reaction can create a white ashy build up that can generally be found on the low pressure side of the system. This can usually be seen in the pump, pump inlet fitting, and the fitting in the holding tank. It is usually not as prevalent of a problem on the high pressure side of the system because of the increase in pressure here.

This is the reason the majority of the alcohol injection companies use nickel platted brass and composite fittings though out there systems. Some companies even use plated nozzles to remove non coated brass 100% from there system. This might be a little extreme because the nozzle is on the high pressure side of the system. But will remove the chance of build up in the system. Thus, if less non brass is used there is less chance of the white ashy buildup.

Now, if you have non coated brass in your system the world is not coming to an end. If you are aware of the problems with brass then preventive maintenance will keep you out of trouble. I would recommend cleaning the filter in your system every three months. Also, it would be a good idea to take your pump apart to clean the valves, seals, etc at least once a year.

Original article can be found here
http://www.alcohol-injection.com/for...stems-670.html

 

so its the same rxn as methanol oxidising aluminum to alumina, Al2O3

Zn to ZnO?

 

Not sure of what its becoming. Brass is btw Cu3Zn2
roughly 40 zinc and 60% copper, but beyond that I don't know much.

 

i just looked up swagelok's material compatibility chart:
1 = excellent, 4 = unsatisfactory

316 stainless steel = 2
Brass = 2
Alloy 400, aka Monel - a CiNi alloy = 1
Titanium = 1

Polymer wise:
PerFluoroAlkoxy/PolyTetraFluoroEthylene = 1
Viton = 4
Buna-N = 1
Delrin = 1

After reading your post, i thought that i should have used full 316SS for my setup - instead of 316SS/Brass.....the brass fitting do not have a silver anti-sieze like the stainless steel fitting, less chance of becoming loose in an environment full of vibration



really surprised that brass is rated the same as 316 stainless steel!

 

 

slowcar2,

interesting info... my Alkycontrol system is brass and stainless.

hc

 

Yea, its just the combing of the 3 chemical meth, water, air is where the problem is. We noticed this problem over a year ago and moved on to coated fittings ourself. When it boils down to it coating is the key, or using 316 which is pricier than coating brass.

Most people with the uncoated brass may never have problems. I have seen quite a few that have.