SKC Ultraflo Calibrators - Operation Instructions Manual

Physics of Measurements: At room temperature, all gases obey - to a very close approximation - the ideal gas equation PV = nRT, where P is the pressure in newtons per square meter, V is the volume in cubic meters, n is the number of moles of gas, R is the empirically determined gas constant with the approximate value 8.31 joules/mole degrees Kelvin and T is the temperature in degrees Kelvin. The method of measuring flow rates in the UltraFlo Calibrator is the technique known as the soap film bubble test. A frictionless soap film is suspended perpendicular to the air flow up a small bore tube. This film forms a complete seal across the tube. The effect causes the soap film to move along the tube at exactly the same rate as the air flow. Knowing a measured distance and tube bore size, a volume can be calculated. Thus, a flow rate can be determined by the movement of soap film across a fixed volume per unit of time. This technique is classified as a Primary Standard.