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CHAPTER NINE
TEMPERATURE COMPENSATION
9.1 Purpose
The temperature of a fastener affects the overall physical length, as well as the
velocity of a fastener. As the temperature of a fastener increases, the ultrasonic
length increases at a rate greater than the physical change in length. If the user
intends to measure the same fastener at different time intervals over the service life
of the bolt, temperature compensation is very important to produce accurate results.
However, if a fastener will only be measured once, never to be measured again,
temperature compensation is not needed, as long as the reference length and
elongation are measured at the same temperature and time.
The thermal expansion of the fastener and the ultrasonic change in velocity as a
result of temperature are two separate effects. However, for the purpose of the
MiniMax, they are combined in a single factor known as the Temperature Coefficient
(Tc). The sections that follow outline the procedures for selecting and using the
temperature compensation mode with the accessory temperature sensor.
9.2 Manual Mode
The manual mode option relies on the user to enter in the current temperature before
measuring. This is useful to those users that do not require temperature
compensation, or have an external temperature device measuring the temperature.
1) Press the
multiple times to tab right, and the
UTIL menu is highlighted and displaying the submenu items.
Selecting Manual Temperature Mode
key once to activate the menu items tab. Press the
key multiple times to tab left, until the
91
key
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