SM0486
LESSON 2.
PRESSURE MEASUREMENT AND DEVICES
AIPD Subcourse Number SM0486...........MECHANICAL
AND
ELECTRO-MECHANICAL
MEASUREMENT PRINCIPLES
Lesson Objectives......................Given lesson objectives and supportive text,
you should be able to answer all exercise
questions pertaining to pressure principles,
pressure gages, barometers, and manometers
with no errors.
Credit Hours...........................Two
TEXT
1.
INTRODUCTION
Your job assignment is the mechanical-electromechanical section includes the
calibration of all types of pressure measuring and indicating devices.
You must
know the principles related to the operation and calibration of the pressure
measuring equipment sent to your section. The information in this lesson explains
the pressure principles associated with pressure measurements and the operating
principles of some pressure measuring devices.
2.
PRESSURE PRINCIPLES
a. When the term "pressure principles" is used in this section, we are
referring to the theories and laws of physics which are applied to the following:
Definitions and terminology associated with the physical forces which affect
and are affected by pressure.
The nature of fluid pressure and its transmission in and through fluids.
Atmospheric pressure and vacuum.
b. Definitions and Associated Terminology. Most of the definitions for terms
used in this chapter are identified as they are needed.
One of the paragraphs
which follows extends the definitions for mass and weight as they apply to pressure
measurements.
The remaining paragraphs explain additional terms associated with
pressure measurements.
c. Mass and weight are two of the fundamental quantities which must be
clearly defined when used with pressure measurements.
The mass of a body is a
measure of the matter which the body possesses.
Although the mass of a body is
expressed in the same units as weight (grams, pounds, etc.), they are not the same.
The weight of a body is the pull or force
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