Glossary of Industry Definitions

This Glossary contains many of definitions for terms commonly used on this site and by the industries we serve.

Use this glossary in combination with these web pages as a standard reference.


316SS: 316 grade stainless steel is the second most common austenite steel. Also called marine grade stainless, it is used primarily for its increased resistance to corrosion. Low-carbon versions, for example 316L or 304L, are used to avoid corrosion problems caused by welding. The "L" means that the carbon content of the alloy is below 0.03%, which reduces the sensitization effect (precipitation of chromium carbides at grain boundaries) caused by the high temperatures involved in welding.

Activated Sludge: Sewage mixed with bacteria and protozoa that thrive and multiply in it and lead to its oxidation (see biological oxygen demand).

Autotroph: An organism capable of synthesizing its own food from inorganic substances, using light or chemical energy. Green plants, algae, and certain bacteria are autotrophs.

BOD5: The amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter. Found op

DPD Method: An analytical method for determining chlorine residual utilizing the reagent DPD (n-diethyl-e-phenylenediamine). This is the most commonly and officially recognized test for free chlorine residual.

Heterotroph: An organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition.

Inductive conductivity measurement: Using a coil to induce a current in the secondary coil. Since both coils have no direct contact to the media this method is sometimes called non-contacting conductivity or - due to the "doughnut" shape of the coils - torroidal conductivity. This method makes it possible to measure in concentrated acids, alkalis, and aqueous solutions with high solids content.

NPOC: Non-purgeable Organic Carbon:

NDIR Detector: a Non-dispersive Infrared Detector.

ORP: Reduction potential (also known as redox potential, oxidation / reduction potential, ORP, pE, ε, or E_{h}) is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. Reduction potential is measured in volts (V), or millivolts (mV). Each species has its own intrinsic reduction potential; the more positive the potential, the greater the species' affinity for electrons and tendency to be reduced. ORP is a common measurement for water quality.

pH: a measure of acidity and alkalinity of a solution that is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity and on which each unit of change represents a tenfold change in acidity or alkalinity and that is the negative logarithm of the effective hydrogen-ion concentration or hydrogen-ion activity in gram equivalents per liter of the solution; also : the condition represented by a pH number.

Torroidal Conductivity: See Inductive Conductivity

TOC: The TOC (Total Organic Carbon) is one of the most important composite parameters in the assessment of the organic pollution of water. Since it includes all carbon compounds as one mass, it is exactly defined and an absolute quantity. Therefore, it may be determined directly.

Related parameters include Total Carbon (TC), Total Inorganic Carbon (TIC), Disolved Organic Carbon (DOC), Particulate Organic Carbon (POC), Volatile Organic Carbon (VOC) and Non-Purgeable Organic Carbon (NPOC). The connections between these sum parameters and their meanings are shown in the following figure:

Relations between TC, TOC and TIC
Extracts of DIN EN 1484:1997-08

TC "The organic and inorganic carbon in water, including the elemental carbon"
TIC "The carbon contained in water; elemental carbon, total carbon dioxide"
TOC "The organic carbon in water, bound on dissolved or suspended substances. Elemental carbon will be also determined"
"The total organic carbon (TOC) is a measurement method for the content of carbon of dissolved and undissolved organic substances in water"

TNb: Total Bonded Nitrogen

TOD: Total Oxygen Demand. Online analyzers for the measurement of Total Oxygen Demand have been available since the 1970s. After the rise of the COD-dichromate method, TOD had been in decline in many countries, while COD has become common for the analysis of wastewater. However, total oxygen demand is a reliable and reproducable parameter for the measurement of oxygen demand in water. In the United States TOD is commonly used and has been standardized as ASTM D6238.

TOD correlates easily to the COD and, therefore, is a prefered alternative to COD measurement. Moreover, it is suitable for online measurement, especially using the thermal combustion method at 1200°C.

PTFE: Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The best known brand name of PTFE is Teflon by DuPont Co.

PTFE is a fluorocarbon solid, as it is a high-molecular-weight compound consisting wholly of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE, as fluorocarbons demonstrate mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE has one of the lowest coefficients of friction against any solid.

PP: Plypropolene

Teflon: See PTFE