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2012-08-01 06:50:07

Show Answers:

  1. What is the commonly accepted value for air pressure at sea level?
    • (assuming 1 atm = 101.3 kPa)
    • Or
    • 1 ATM 
  2. Define the terms differential pressure, absolute pressure and gauge pressure.
    • Absolute pressure is zero-referenced against a perfect vacuum, so it is equal to gauge pressure plus atmospheric pressure.
    • Gauge pressure is zero-referenced against ambient air pressure, so it is equal to absolute pressure minus atmospheric pressure. Negative signs are usually omitted.
    • Differential pressure is the difference in pressure between two points.
  3.  If a gauge is referenced to absolute zero what pressure would it read at sea level?
    101.3 kPa - 0 = 101.3 kPa
  4. What is a manometer and how can its sensitivity be increased?
    A Manometer is a device which can be used to measure pressure of fluids(i.e liquids and Gases).

    PRINCIPLE: Manometers are those pressure measuring devices which are based on the principle of balancing the column of liquid(whose pressure is to be found) by the same or another column of liquid. They are of two types

    1. simple manometers

    2.Differential manometers
  5. What is a bourdon tube and how can its sensitivity be increased?
    A Bourdon Gauge is a pressure indicator, it works with a "C" shaped tube oval in cross section that tries to straighten under pressure. When the tube tries to straighten it pulls on a connecting arm which turns a needle that is against a card that states the pressure.

    Decrease the atmosphere in the sealed end of the gaugeIncreased by axing more air or pressure to the sealed end of the tube
  6. How does a strain gauge measure pressure?
    A strain gauge is a device used to measure the mechanical strain on an object or structure. When an object is under a lot of pressure, the material can slowly fatigue and begin to subtly bend. These bends, nearly impossible to see with the naked eye, can be early indicators that a building is aging or beginning to buckle. 
  7. How does a piezo resistive cell measure pressure?
    A piezoelectric sensor produces a voltage when it is "squeezed"; the voltage is proportional to the force applied. 
  8. What is a snubber used for? Name 2 types.
    The Adjustable Pressure Snubbers protect pressure instruments against fluctuations, surges, spikes and fluid hammer. The fine thread adjustable valve allows you to fine tune harmful harmonic vibration from the fluid systems and isolate the instrument from process when service or replacement is necessary. These Pressure Snubbers are designed to provide fully field adjustable dampening. By using our Adjustable Pressure Snubbers, you will alleviate surges and pulsations to assure steady pressure readings and extend the life of your instrument.

    • Hydraulic Systems
    • Hydraulic Presses
    • Fire Pumps
    • Gauge Protection
    • Vulcanizers
    • Centrifugal Pumps
    • Manifolds
  9.  Mercury (Hg) has a specific Gravity of 13.6. How many mmHg is equivalent to 1 m H2O?
    1mm Hg = 13,16 mm H2O

    760 mmHg = 1 bar

    1 bar = 10 m H2O

    1 mmHg =10000/760 mm H2O
  10. A 10 m tank is full of water. What is the pressure at the bottom of the tank in mmH2O and in kPa?
    • P= row x G x H
    • 1025kg/m salt water x
    • G = 9.81ms. X
    • H = 3810m
    • =p = 38.3 pa x 10 to the power 6

    = 38.3 mpa

    • Force = pressure x area 
    • 38.3 x 10 power 6 x .01m2
    • = 3.83  x 10 to the power 6N
    • FORCE = 3.83MN