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Glossary
NPT
National Pipe Thread. A U.S. standard for
tapered threads used on threaded pipes
and fittings.
NTU
Nephelometric Turbidity Unit.
°Oechsle (°Oe)
°Oechsle is mainly used in the German, Swiss
and Luxenburgish winemaking industry to
measure the sugar content of must. The °Oe
scale, one degree Oechsle corresponds to one
ram of difference between the mass of one
liter of must at 20°C and 1 kg (the mass of 1
liter of water at same temperature).
Open Junction
This type junction, found in reference half-
cells, is filled with a special gel which comes
into direct contact with the solution to be
measured. An advantage of an open junction
is low contact resistance and it is virtually
impossible to clog.
Opto-isolator
Inelectronics, anopto-isolator is anelectronic
device designed to transfer electrical signals
by utilizing light waves to provide coupling
with electrical isolation between its input
and output.
ORP
Oxidation Reduction Potential. Solutions can
be graded as oxidizing or reducing based on
measurement of ORP values.
OSHA
The
Occupational
Safety
and
Health
Administration.
OUR
Oxygen Uptake Rate. Used to determine the
oxygen consumption or respiration rate; is
measured in mg of oxygen consumed per liter
per hour.
PAN
1-(2-pyridylazo)-2-naphtol (indicator)
PCU
Platinum Cobalt Unit.
PD Controller
Proportional Derivative controller.
PEI
Polyetherimide.
PELs
Standards for the length and intensity of
exposure to certain elements.
Pfund Scale
The Pfund scale is a color grader used to
provide readings of the range of honey colors.
There are seven color classifications for
processed honey; water white, extra white,
white, extra light amber, light amber, amber
and dark amber. Traditionally, the Pfund color
grader works by visually comparing a wedge-
shaped glass container of honey with an
amber glass wedge.
pH [NIST]
The negative logarithm of the hydrogen ion
activity has been given the symbol pH. The
original definition was in terms of hydrogen
ion concentration. The present definition
of pH is associated with the “effective”
concentration of hydrogen ion.
pH Glass Electrode [IUPAC]
Hydrogen ion responsive electrode usually
consists of a bulb, or other suitable form
of special glass attached to a stem of high-
resistance glass complete with internal
reference electrode and internal filling
solution system. Other geometrical forms
may be appropriate for special applications.
Photometer
An instrument used for measuring of
photometric quantities by means of a
photoreceptor.
PID Controller
Proportional-Integral-Derivative controller.
PLC
Programmable Logic Controller.
17
Glossary
17.14
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