42.
The major disadvantage of the Pitot tube is that it is:
a. Not the standard instrument for measuring the velocity of air in ducts.
b. Used to measure the velocity pressure contours inside the ducts.
c.
Not used with the inclined mamometers.
d. Not direct reading.
43.
Because the air flow is not uniform in the cross section of a duct, how many
diameters should be measured straight run downstream or upstream of any
interference for greater accuracy?
a. At least 7.5 diameters of straight run downstream or 1.5 diameters upstream
from any interference.
b. At least 7.0 diameters of straight run downstream or 1.0 diameters upstream
from any interference.
c.
Not more than 7.5 diameters down run or 1.5 diameters upstream.
d. Two thousand feet either way.
44.
Which is true about Pitot tubes?
a. These tubes are to be used during corrosive or variable temperature
conditions.
b. Corrections do not have to be made if the temperature is plus or minus 30F
from standard.
c.
They are not used in small diameter ducts less than 3 inches or in orifice type
openings.
d. They are used to measure velocities less than 600 fpm.
MD0165
4-36
Previous Page
