WATER JET CONFERENCE - Waterjet Technology Association

POLYMERBLASTING - A CHEMIST'S POINT OF VIEW
Dr. W.G. Howells
Berkeley Chemical Research, Inc.
Berkeley, California 94720
ABSTRACT
The purpose of this paper is to describe the background applications, chemical and other
important considerations of the use of SUPER-WATER concentrated industrial water blasting
additive. Because SUPERWATER is a polymer, the process in which it is used is often called
polymerblasting although water is still the principal blasting medium. The polymer is used at a
concentration of only 0.3% but even at this low concentration the distinctive characteristics of
the resulting jet flow are quite remarkable.
BACKGROUND
For many years it has been known that the inclusion of low concentrations of various
additives in water bring about dramatic changes in flow. These additives can be soluble or
insoluble in water and although polymerblasting in the context of this discussion centers on a
soluble polymer, it is worthwhile noting some of the generally important historical landmarks.
Initially, the additives were not intentionally added. Exactly 100 years ago (1883), there existed
records of increased flow rate in silt laden rivers (1): the term "drag reduction" to describe this
general phenomenon was not coined until 80 years later by Savins (2). Credit for the first drag
reduction experiment with an additive should probably be assigned to Hele-Shaw (3). He was
interested in the skin friction on marine animals and was able to show that the addition of fresh
bile, a somewhat bizarre additive, to water appeared to bring about reduced flow resistance (or
drag reduction). Since those days, a large number of publications has appeared on drag reduction
and in the period from 1956 to 1976, it is estimated that nearly 1,000 publications (4) addressed
themselves to this topic. Despite these extensive research activities, however, no totally
satisfactory theory has yet been developed to explain drag reduction (5).
A second characteristic exhibited by water containing additives is that of jet focusing. In
1964 (6) an article was published describing fire fighting with (so-called) viscous water. It was
noted that "once the water using this viscous water (actually a solution of sodium
carboxymethylcellulose) has left the nozzle of the fire fighting hose, it is less likely to be
dispersed into a spray by the wind; thus, the jet travels further than ordinary water would". Other
articles describing jet cohesion appeared in Chemical Engineering (7) and Fire Engineering (8).
Within the same general time frame that these observations of water jet cohesion were published,
Gadd (9) reported parallel findings for jets (containing dye) submerged in water. Of even greater
significance to this discussion, however, is that Summers (10) described the use of polymeric
additives in high pressure waterblasting.
In 1973, Russian workers (11) reported the "Destruction of metallic obstacles ("objects"
would have been a better term) by a jet of dilute polymer solution".
The above is a brief and far from complete account of the knowledge that was available
in 1974 on the use of polymer additives in aqueous solution. It did, however, provide the
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