A supply apparatus comprises a storage tank, a chemical flow pipe to route a chemical solution into a semiconductor processing room, a pressurizing apparatus to supply gas to the storage tank to make the chemical solution flow into the processing room, and an electro-Pneumatic regulator valve to adjust the pressure of the input gas. The flow control device comprises a flow sensor, a set-up apparatus, and a processor for generating a control signal to the pressurizing apparatus depending on a difference between a target value and a measurement value to adjust the flow of the chemical solution in the chemical flow pipe. The flow sensor comprises a hollow cylinder, a choking magnetic core movably positioned inside the hollow cylinder, and a first and second conductive coil wrapped around the outer wall of the hollow cylinder which uses alternating current to generate a magnetic flux and sense a change in the magnetic flux to measure the flow of chemical solution.