Instruction Manual

Model 166T Telescoping Pitot Tube
Dimensions — Operating Instructions
Bulletin H-18
DWYER INSTRUMENTS, INC. Phone: [phone] www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: [phone] e-mail: [e-mail]
©Copyright 2009 Dwyer Instruments, Inc. Printed in U.S.A. 7/09 FR# 72-440948-00 Rev. 2
The Model 166T Telescoping Pitot Tube is a convenient
adjustable length instrument for sensing air flow in a wide range
of duct sizes, extending your reach to 36 inches (91 cm). It is
ideal for almost any air velocity measurement where permanent
mounting is not required. Because of the very small sensing
holes on the tip, flow must be reasonably clean and free from
particulates which could cause blockage.
The Model 166T consists of a standard 1/8˝ diameter Pilot tube
attached to a four-section stainless steel telescoping tube and a
comfortable hand grip designed for ease in maintaining proper
orientation. This device can be used at any length from 11
15
/
32
˝
to 40
7
/
16
˝ (30 to 103 cm). A 3/8˝ (9.5 mm) diameter hole is
required for full insertion. For maximum accuracy, the 1/8˝ diam-
eter tip should be always be extended to its full 3˝ length regard-
less of how far the telescopic sections are extended.
While extending the tip, twist it slowly back and forth until you feel
it engage with the end of the first telescoping section. Next,
extend the Model 166T to the required length and rotate the tele-
40-7/16
[1027]
7/16 [11.11] DIA.
11-15/32
[291.3]
scoping sections to align the tip so it points in the same direction
as the finger grips on the handle. See drawings. Now when unit
is inserted in the duct, you can refer to the handle orientation as
a guide to assuring the tip is pointing into the airstream as
required for best accuracy.
When extending or collapsing the telescopic tube, be sure the
flexible rubber tubing moves freely through the opening in the
end of the handle. The pressure connections on the terminal
block are marked "S" for static pressure and "T" for total pres-
sure. Connect the static pressure to the minus (-) or low pres-
sure port on the manometer or gage and the total pressure to the
positive (+) or high pressure port. See Dwyer Instruments, Inc.
full line catalog for complete air flow measuring instructions, for-
mulas and flow curves.
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