DMDB Doubts

In my December 29, 2010 post at …

Crazy-Competitor-Claims

Wonderer in the Wilderness inquired …

Question 5. A new fluid, DMDB, has been introduced.  Will this improve injection performance on my URD cables?

In that first post I provided an abbreviated answer.  We learned from the abbreviated answer that DMDB is not appropriate for URD cables in particular, because of two inherent inefficiencies.  One inefficiency is by design; the other … well it’s not by design.  I illustrate the first problem nearby.  We call this property of the fluid, “stoichiometric efficiency.”  (Pronounced stoyk-E-O-meh-tric)

Stoichiometry defines the quantitative relationships that exist between the reactants and products in chemical reactions.  When any of the six monomers in the figure nearby react with water they form desirable products and some undesirable by-products.  The percentage of desirable products compared to the total is the stoichiometric efficiency.  The stoichiometric efficiency can be calculated knowing only the chemical composition.  In the graph titled “Hydrolyzate Concentration in Condensate,” this math has been performed for all alkoxysilanes of commercial significance as a function of the number of alkoxy carbon atoms, from one to twelve.  The six globally significant alkoxysilanes are each illustrated on the figure and their positions within the hydrolyzate concentration continuum are pinpointed.  The table nearby defines the acronyms and provides commentary on each monomer.

Methanol, a one-carbon alcohol, is an undesirable by-product of the first three fluids, which are generally deployed in small diameter URD cables.  At very high operating temperatures (i.e. conductor temperatures above 55°C), methanol can corrode aluminum.  Fortunately, the methanol generally diffuses out of the system very quickly and small diameter cables do not routinely experience 55°C conductor temperature.  As a consequence the risk of methanolic corrosion is quite low in applications where these fluids are properly deployed.  All Novinium fluid formulations include Tinuvin^® 123, which stabilizes the patina on aluminum strands and further reduces the risk of methanolic corrosion.  Patina (pronounced pa-TEE-na), is the natural corrosion resistant coating that forms on metals such as aluminum.

To address methanolic corrosion in larger conductor cables CableCURE^®/DMBD fluid was introduced.  DMDB’s undesirable by-product is butanol, a four-carbon alcohol.  The good news is that butanol is unlikely to cause aluminum to corrode; the bad news is that it comes at the price of stoichiometric efficiency.  In the figure nearby, I have circled in blue the portions of the silane monomers, which yield undesirable by-products.  For the DMDBS monomer, about two-thirds of the molecule provides no benefit to the cable.  Because of its low stoichiometric efficiency, you won’t find this frog suggesting that it be used for small diameter cables – especially when there are much better solutions in wide commercial application.

How about larger conductor cables?  Does DMDB do the trick with those?

In the 1980’s the guys at Du Pont discovered that alcohols with 6 to 24 carbon atoms are “tree growth inhibitor[s] capable of imparting at least a thousand-fold increase in electrical endurance as measured by an accelerated test procedure.” (See U.S. Patent 4,206,260.)  In the figure nearby my green laser is pointing to a lightly-green-shaded region of the graph that falls within the Du Pont discovery.  Instead of undesirable by-products, these longer-carbon-chain alcohols are superb dielectric enhancement fluids.  In other words, with Novinium’s Ultrinium™ 733 fluids there are no undesirable by-products, and hence the stoichiometric efficiency is 100%.  Like the 4-carbon alcohol by-product of DMDBS, the 8-carbon alcohol will not corrode the aluminum.  High performance – no compromises!

Finally, to get the total efficiency, it is necessary to consider other efficiencies including catalytic efficiency.  In my January 3, 2011 post, Catalytic Considerations – Component I, I shed some frog wisdom on that subject.  There is also a technical paper in the Novinium library titled Considerations for Injecting Cable with High Conductor Temperature, which provides even more detail.  The bottom line is DMDBS is definitely not appropriate for small conductor URD cables.  For large conductor cables the best choice is Ultrinium™ 733 fluid which enjoys 100% stoichiometric efficiency and a much higher catalytic efficiency.

Always state-of-the-art,

Thermonuclear Bull Frog