The Dwyer 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 1115/32˝ to 407/16˝ (30 to 103 cm). A 3/8˝ (9.5 mm) diameter hole is required for full insertion. For maximum accuracy, The 1/8˝ diameter tip should be always be extended to its full 3˝ length regardless 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 telescoping 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 pressure. Connect the static pressure to the minus (-) or low pressure port on the manometer or gage and the total pressure to the positive (+) or high pressure port. See Dwyer bulletin H-11 for complete air flow measuring instructions, formulas and flow curves.