Installation and Operation Instruction PT Series Pitot Tube AUTOMATION COMPONENTS, INC Version : 7.0 2305 Pleasant View Road I0000376 Middleton, Wisconsin 53562 Page 1 of 3 www.workaci.com (888) 967-5224 PLEASE READ THE FOLLOWING INFORMATION BEFORE INSTALLATION INSTALLATION Select the correct PT model to fit the duct; to get a good reading of the velocity pressure, the PT sensor must be at least half the width of the duct when inserted. See Figure 1. For best accuracy, the PT needs 10 straight duct diameters upstream and downstream from any elbows or reducers. Model # "L" Insertion Length Recommended Duct Size Number of Sensing Points PT 3" 3" (7.6 cm) 4" - 6" (10.16cm - 15.24cm) 1 PT 5.2" 5.2" (13.2 cm) 6" - 8" (15.24cm - 20.32cm) 2 PT 7.5" 7.5" (19.0 cm) 8" - 10" (20.32cm - 25.4cm) 3 PT 9.7" 9.7" (24.6 cm) 10" - 18" (25.4cm - 45.72cm) 4 Figure 1 AUTOMATION COMPONENTS, INC Version : 7.0 2305 Pleasant View Road I0000376 Middleton, Wisconsin 53562 Page 2 of 3 www.workaci.com (888) 967-5224 MOUNTING The PT sensor requires a 7/8” (2.2cm) hole in the duct for mounting, and has a flange with gasket and two 3/16" (4.76mm) holes spaced 3.3" (8.38cm) center-to-center, see drill template Figure 3. The sensor must be installed so the flow arrow imprint is pointing in the direction of the duct’s airflow. See Figure 2. The flange should then be tightly mounted to the duct using two sheet metal screws or rivets inserted in the mounting holes. The flow performance chart can be used to determine the flow based upon the measured differential pressure. See Figure 4. Duct Static Flow Figure 2 DRILL TEMPLATE Figure 3 ALL DIMENSIONS: Inches [mm] AUTOMATION COMPONENTS, INC Version : 7.0 2305 Pleasant View Road I0000376 Middleton, Wisconsin 53562 Page 3 of 3 www.workaci.com (888) 967-5224 Figure 4 CONNECTIONS When connecting the tubing, be extremely careful that no sharp bends are made, this may cause leakage as the tubing ages and stretches. Using 1/4" (6.35 mm) OD poly tubing, connect the "H" port to a differential pressure gauge or transmitter "High" input port, and the "L" port to the gauge or transmitter's "Low" input port. MAINTENANCE To ensure reliable performance, the sensor pickup openings must be kept free of dirt and dust accumulation. FORMULAS For rectangular ducts, KCFM = KFPM x (W" x H"/144)2 (with duct cross-section measurements in inches). For round ducts, KCFM = KFPM x (πr2/144)2 (with duct cross-section measurements in inches). For Flow For Volume ∆P = (FPM/KFPM)2 FPM = KFPM x SQRT(∆P) ∆P = ቀ CFMKFPM X Area ቁ2 CFM= KFPM x SQRT (∆P) x Area Feet Per Minute in a VAV box equals the (relevant model’s) K factor times the square root of the differential pressure (in “wc”). Cubic Feet per Minute in a VAV box equals the relevant sensor model’s K factor times the square root of the differential pressure (in “wc”) times the cross-section area (in square feet). Next >