Profile: Harwil Corp. design and manufacture electro-mechanical fluid flow and liquid level switches. Our product line includes flow & level switches, pools, temperature sensors and controller & relays. Our Model Q-4E features a continuous adjustment while operating line pressure to 300 psig. The four individual drag disk options plus continuous adjustment provides wide operating range of particles used in the contaminated fluids. Our unique L-21 and LC-1 provide latching contacts for pump up/pump down control of solenoid valves or pumps. The Model SDC-101 provides a time delay to allow a pump to establish prime before control is turned over to the flow switch. Model CF-112 controls chemical injection pumps based on flow of the bulk liquid.