Emerson Process Management 3081 pH/ORP instruction manual 133

MODEL 3081 pH/ORP	SECTION 16.0
	GLOSSARY
Solution ground	A solution ground is a metal post or ring incorporated into the sensor body and mak-
	ing contact with the process stream. Glass and reference impedances are meas-
	ured by applying a voltage pulse between the electrode and the solution ground.
Solution temperature	The pH of many solutions, particularly alkaline ones, is a function of temperature.
compensation	Therefore, although the concentration of the chemical causing the pH remains
	constant, pH will change if the temperature changes. Solution temperature com-
	pensation is a technique for converting pH measured at any temperature to the
	pH at a reference temperature. The almost universal reference temperature is
	25°C. Different solutions require different solution temperature compensation.
Sub-menu	Sub-menus are a group of related menus collected under a single menu.
Standardization	As used in the Model 3081 pH/ORP manual, standardization is the process of
	forcing the transmitter reading to match the reading of a second pH meter.
Temperature compensation	A plot of voltage against pH a straight line, called an isotherm. The slope of the
	isotherm is a function of temperature, so a measured cell voltage corresponds to
	a different pH, depending on temperature. Temperature compensation is the
	process of selecting the correct isotherm. The Model 3081 pH transmitter per-
	forms automatic temperature compensation.
Warning limit	A warning advises the user that sensor performance is degrading. Measurements
	might still be acceptable, but the user should determine the cause of the problem
	and correct it as soon as possible. Not acting when a warning limit is exceeded
	may ultimately lead to sensor failure.

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