Sanitizing Aerator

steve_flack · Post by **steve_flack** » Tue Apr 17, 2007 1:09 pm

HYpochlorous acid is HOCl. It is the acid form of sodium hypochlorite NaClO which is in bleach. It is also the acid given when chlorine is dissolved in water (as well as HCl).

Because it's a stronger oxidant than chlorine it's more effective at knackering biological chemical pathways so killing stuff.

maxashton · Post by **maxashton** » Tue Apr 17, 2007 1:26 pm

I meant the reaction itself. I am too rusty to balance equations in my head. Perhaps i will do a chemistry thing at the OU!

steve_flack · Post by **steve_flack** » Tue Apr 17, 2007 2:11 pm

NaClO + HOAc -> HOCl + NaOAc

Post by **Andy** » Tue Apr 17, 2007 2:16 pm

According to my calcs the ratio of bleach to water required is 1:640 (the same for the white vinegar addition).

Which gives:-

About 1 and a third teaspoons of bleach per 5 litres of water.
Then add 1 and a third teaspoons of white vinegar to the water/bleach mix.

Bleach is about 28p / two litres and white vinegar approx 70p / 500ml I think.

That's a lot of sanitiser for a quid

steve_flack · Post by **steve_flack** » Tue Apr 17, 2007 2:21 pm

IIRC the StarSan guy said it worked out at 80ppm.

Can you accurately measure a third of a teaspoon? I can't. I'd use a syringe.

maxashton · Post by **maxashton** » Tue Apr 17, 2007 3:04 pm

so what, 6.5(?) ml of bleach, same of acetic in 5L of water will yield (effectively) a contact sanitizer.

According to one site i read, it will inactivate e.coli within milliseconds, for example.

maxashton · Post by **maxashton** » Tue Apr 17, 2007 3:09 pm

How long will HOCl take to decay? The guy from 5 Star said it will start to go cloudy when it starts to decay, any idea how long that takes? I presume its rather unstable.

maxashton · Post by **maxashton** » Tue Apr 17, 2007 3:12 pm

Escherichia coli exposed to hypochlorous acid lose viability in less than 100 ms due to inactivation of many vital systems. [2][28][29][30][31] Hypochlorous acid has a reported LD50 of 0.0104 ppm - 0.156 ppm[32] and 2.6 ppm caused 100% growth inhibition in 5 minutes.[25] However it should be noted that the concentration required for bactericidal activity is also highly dependent on bacterial concentration.[20]

steve_flack · Post by **steve_flack** » Tue Apr 17, 2007 3:14 pm

maxashton wrote:How long will HOCl take to decay? The guy from 5 Star said it will start to go cloudy when it starts to decay, any idea how long that takes? I presume its rather unstable.

I wouldn't store it diluted.

maxashton · Post by **maxashton** » Tue Apr 17, 2007 3:15 pm

Fair cop. Thanks Steve!

UserDeleted · Post by **UserDeleted** » Tue Apr 17, 2007 9:06 pm

maxashton wrote:I was thinking of using my pressure cooker for this purpose, UD. Poor man's autoclave, eh? What do you use to raise the items off the bottom of the PC?

The Veg Basket Turned Upside down, with the trivet on top of that. We had to buy a new Hi-Dome pressure cooker as our old one (non hi dome) we couldn't get parts for . . . honest (*). I can just about fit my 1L conical flasks in them which makes it great for preparing sterile wort for starters. Then you have preparing agar for slants and plates, and all the other yeast ranching stuff.

(*) I sort of gave the whole game away when I started referring to it as My autoclave though

maxashton · Post by **maxashton** » Tue Apr 17, 2007 9:17 pm

Yeah, bad move.

Fortunately, the kitchen is *my* turf, as are all the toys in it.

Jim's Beer Kit

Practical Homebrewing

HomeBrew Forum

Sponsored by BREW-SCHOOL

Sanitizing Aerator