Mailing List Archive

Mailing List: techdiver

Banner Advert

Message Display

Date: Sun, 26 Mar 2000 12:28:45 -0600 (CST)
From: Ronald D Thompson <rthomps@co*.or*>
To: techdiver@aquanaut.com
Subject: Tri-Mix fudge factors
Experienced tri-mix home brewers on the List:

I'm considering blending some helium and EAN36 to yield a specific
tri-mix (this would be my first attempt at blending tri-mix), and I'd like
some guidance regarding fudge factors to use in order to compensate for
helium compressibility.

My ideal gas calculations would have me first half-fill an "empty"
cylinder with helium and then top off with EAN36, to obtain a tri-mix
consisting of 18% O2, 50% He, and 32% N2.  (At MOD = 225 fsw, this mix
has PO2 = 1.41 ata, END = 71.5 ata, and AED = 96 fsw.)

Now, my admittedly naive understanding of helium compressibility suggests
that I really need to start with more than half-filling the cylinder with
helium to obtain the desired mix.  My question is:  How much more?
Specifically, if I'm using twin LP 112's with an ending pressure of 2640
psig, what fudge factor should I use to end up with tri-mix 18/50?  Same
question if, instead, ending pressure is 3500 psig?

Thanks in advance for your suggestions.

Ronald


--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]