Which method would NOT be used to feed dry chemicals?

The method that would not be used to feed dry chemicals is a plunger feeder. This type of feeder generally operates by using a plunger mechanism to move or push material through a feed chute or discharge area. Typically, plunger feeders are more suited for handling liquids or slurries rather than dry solids, as they rely on the hydraulic or mechanical pressure to perform their function.

In contrast, the screw feeder, vibrating trough, and rotating feeder are all designed with mechanisms specifically tailored for handling dry chemicals. Screw feeders utilize a rotating screw to convey and dose materials effectively, ensuring consistent flow. Vibrating troughs use vibration to move material along a surface, enabling precise and uniform feeding of dry substances. Rotating feeders, like rotary valves, are effective at managing granular materials by utilizing a rotating mechanism that allows for controlled discharge without interrupting the material flow.

Each of these appropriate methods ensures that dry chemicals can be handled efficiently and accurately in various processing and dosing applications, which distinguishes them from a plunger feeder.