Issue link: https://iconnect007.uberflip.com/i/1309864
NOVEMBER 2020 I PCB007 MAGAZINE 67 Figure 4: An extremely sensitive and accurate immersed SG sensor can be made from a purchased GEM-level switch that has a threaded hollow rod attached and two threaded nuts. Figure 3: An overview of 48 different ranges of commercial hydrometers. approach, it can measure the concentration of dissolved solids in solutions. Six different methods are used in the industry: 1. Hydrometers 2. Displacers 3. Hydrostatic head 4. Radiation 5. Weight in fixed volume 6. Vibrating U-tube The least expensive way to measure SG is with a hydrometer (Figure 3). These can be purchased at an incredibly low price. They come in many ranges, but all require the use manually, as shown in the beaker. The hydrometer is a displacement type of SG sensor. Another type of displacer is the total immersion displacer. The SG sensor in Figure 4 is made from a GEM-level switch. A CPVC plastic rod is drilled out to a specific depth