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F) Suspensions & Suspended Solids
Products with high percentages (5%) of suspensions or suspended solids, or any hard solids,
such as sand, are not recommended for the 682 series meter. Products with a low percentage
of soft suspensions or suspended solids (<5%) may be metered at a reduced flow rate. It is
recommended that the flow be reduced by 20% from the flow rate for a similar product
without suspensions or suspended solids.
G) Foreign Materials
Products that are to be measured may have foreign materials present. The inlet side of any
positive displacement meter should be equipped with a strainer to protect the meter and
accessories from damage in the system. The strainer should be suitable for 1-1/2” or 2”
piping with an appropriate screen mesh size. A minimum of 40-mesh screen is
recommended for petroleum service.
H) pH
The resistance of any metal to the effects of high or low
PH is difficult to calculate because of the varying
concentrations and corrosiveness of fluids, particularly
blended products. At right is a generalized
recommendation for pH resistance for metals used in
the Series 682 meter. For specific application, consult
the factory.
——— ALKALINE REACTION ——►
I) Viscosity
Viscosity is the property of a fluid that is a measure of its resistance to flow. Among the
earliest to express this quantitatively was Sir Isaac Newton. He reasoned that the viscosity of
a liquid was proportional to its shear stress (or resistance to shear). In other terms, viscosity
is basically constant with shear and flow rate. Liquids that behave in this manner are referred
to as “Newtonian” liquids. Petroleum fluids, water and similar chemicals are categorized as
Newtonian liquids.
Other types of fluids are grouped into a general category called “Non-Newtonian”. Among
the fluid types that are categorized as non-Newtonian are dilatants, plastic, pseudoplastic and
thixotropic liquids. Non-Newtonian liquids are characterized by viscosity that changes with
the rate of shear as compared to the Newtonian fluids where viscosity is essentially a
constant. As a consequence, the performance of a fluid through a flow meter is much more
predictable for Newtonian fluids than for Non-Newtonian liquids.
Many of the more viscous liquids pumped through the 682 series rotary flow meter are
plastic and pseudoplastic and as such are reduced in effective viscosity after being pre-
sheared by the pump.
Recommended
Material pH Range
Aluminum 5 –8
Ductile Iron 5.5 –11
Ni-Resist 5.5 –14
Stainless Steel 0 –14
