Insert the static pressure tip into the test port on the return side with the tip facing the airflow. Read and record the negative static pressure. Don’t forget to insert port plugs into the test ports when you’re done testing. STEP 6: Calculate the system’s Total External Static Pressure by adding the two values.Click to see full answer. Furthermore, how do you calculate static pressure in a duct?Add total elbow equivalents to the length of straight duct to arrive at the total system duct length. Multiply the static pressure for 100 feet of duct by the percentage of 100 feet that you have. This will be the static pressure caused by the ductwork. what is total static pressure? Total External Static Pressure. Generally, when measuring total external static pressure, measure the pressure at the point where airflow enters the equipment and where the airflow exits the equipment. The pressure entering the equipment is a suction or negative pressure. Also to know is, what is a normal static pressure in ductwork? Static pressure is one of the most important factors in HVAC design. Simply put, static pressure refers to the resistance to airflow in a heating and cooling system’s components and duct work. The push of the air must be greater than the resistance to the flow or no air will circulate through the ducts.How do you measure static?There are at least three instruments we can use to measuring static: electrostatic fieldmeters, Coulomb meters used with Faraday cups, and non-contacting electrostatic voltmeters. The only meter that actually measures charge is the Coulomb meter.