Founded in 1931, Dwyer Instruments is one of the leading manufacturers of controls and instrumentation products. The company serves various chemical, food, oil, gas, pollution control, and heating, ventilation and air-conditioning companies. It offers products under the brand names, such as Magnehelic, Photohelic, Hi-Flow and Rate Master. Dwyer Instruments manufactures a variety of products that control and regulate pressure, air velocity, temperature, flow, humidity and air quality. The company also provides process control devices, such as fan speed controllers, isolating transmitters, relays, speed switches and switch testers. Additionally, Dwyer Instruments trademarks include Optitrol, Love Controls, Lite Rite, MagneSense and Plast-A-Vane.