DPM TT Series - Duct Traverse Points; Pitot Tube Operation and Placement; Traverse Point Measurement Guidelines

TTSeriesLRManual
Page12
DUCTTRAVERSEPOINTS

PrincipleofOperation:
PitotHead


VelocityPressure*=Total Pressure–StaticPressure

*
CalculatedbytheMicromanometer
ThenoseofthePitotTubeshouldface
directlyintotheairstreamthustheTotal
Pressureflowsdowntheinnertubewhich
isconnectedtotheSignalInport.
Thestaticholesarepositionedaroundthe
sideofthePitotTubeandleadintoan
outertube.Thisisconnected
totheblack
tubingwhichinturnisconnectedtothe
Referenceport.
LogLinearRuleforTraversePointson3Diametersina
CircularDuct:


Ideally traversepoints shouldbeatleastsix
ductdiametersawayfromanybendor
obstructioninthesystem.
ThePitotTubeshouldbeinsertedatright
anglestothewallsoftheductsand
measurementsaretakeninthepositions
showninthediagrams(left).
Thedirectionalpointercanbe
usedto
ensurethatthePitotTubeheadisparallel
totheductwalls.
AlternativeMeasuringPointsandTraverseLines
RelativetoSideLengthsforRegularDucts:



0.061D
0.235D
0.563D
0.437D
0.765D
0.939D
0.074D 0.288D
0.5D
0.712D
0.926D
0.032D
0.135D
0.321D
0.679D
0.865D
0.968D
D
TP
SP