6.4 Temperature Sensor Centering Device:
6.4.1 The temperature sensor shall be mounted through a
snug-fitting device designed for mechanically centering the
sensor in the neck of the flask without vapor leakage. Examples
of acceptable centering devices are shown in Figs. 3 and 4.
(Warning—The use of a plain stopper with a hole drilled
through the center is not acceptable for the purpose described
in 6.4.1.)
NOTE 4—Other centering devices are also acceptable, as long as they
position and hold the temperature sensing device in the proper position in
the neck of the distillation column, as shown in Fig. 5 and described in
10.5.
NOTE 5—When running the test by the manual method, products with
a low IBP may have one or more readings obscured by the centering
device. See also 10.14.3.1.