Kiel probes are used to measure total pressure in fluid
stream where the direction of flow is unknown or varies
with operating conditions. Their correction factor is
0 when used within the ranges outlined below.
Mach Number Range
True total pressure is indicated up to a Mach Number of
1.0. There is a slight drop in yaw in sensing range above
Mach Number 0.3. This decreases averages about 4% for
all types at a Mach Number of 1.0.
Reynolds Number Range
Insensitive to Reynolds Number except at extremely low
velocities for Pitot-Static probes. For air this limiting
velocity is about 4 ft/sec for the smallest size Kiel
This depends on the complete installation, probe, pressure
lines, and manometer. With 1/8" connecting hose up to
20 ft. long and a liquid manometer of 1/4" ID, the Type
B probe will reach equilibrium reading in approximately
15 seconds. Using this time "t" as a standard the other
time constants for average stem lengths will be:
C, D, H
Negligible, especially since the probe is yaw insensitive.
Very High turbulence may cut down the yaw and pitch insensitive
Figure 1. Flow Angles
Boundary effects are small as in all total pressure probes.
However, in steep total pressure gradients as near solid
boundaries or in "trough" behind guide vanes a shift in
the effective center of the probe occurs, so the total
pressure measured corresponds to the streamline 0.5d away
from the geometrical center of the head in the direction
of the higher total pressure as shown in Fig. 3.
Figure 3. Shift in Effective ProbeCenter
Yaw and Pitch Angle Range
The outstanding advantage of Kiel probes compared with
other total pressure probes is complete insensitivity
to direction of flow within certain limits. Their yaw
and pitch characteristics are generally the same although
stem interference on some designs will change one from
the other. Fig. 1 shows these flow angles and Fig. 2 is
a typical calibration curve of a Type A probe. It can
be seen that the correction factor equals 0 up to the
limits of the yaw range and then drops very sharply. The
range is arbitrarily defined as the point where the error
equals 1% of velocity pressure. Symbols used in these
Pt: Total Pressure
Ps: Static Pressure
Ptp: Indicated Total Pressure
The yaw and pitch range for
all types listed above at a Mach Number of .25 are:
+/- 47¡Æ - 40¡Æ
2. Typical Calibration Curve
of Type A Probe
These probes are usually installed through holes large
enough to pass the head as listed on the Kiel Specification
pages. See each individual type for the minimum size.
Special construction including
other material, designs to customer's specifications,
special take-offs, and mounting adapters quoted as requested.
Class = K (Kiel) All stainless steel construction
d = See chart and table - Type A, B, C, D, E, F, R
h = 1/8"- see chart for range in each type
1/4" 5/16" 3/8"
a = 12" - Overall length - inches
m = 1/4" - Reinforcing tube diameter (Omit if no reinforcing required)
= Reinforcing tube length - inches (Omit if no reinforcing required)
e = 1/8" - Take-off diameter (Omit if take-off is same size as stem;
Braze: Silver soldered for use up to 900¡ÆF, this type
supplied unless otherwise noted by N or W in suffix above.
N = High temperature braze for use up to 1,500¡ÆF
W = Welded for use up to 2,000¡ÆF
¨Ï 2002 JungJin Pressure Systems All Rights Reserved.