Test for Total Dissolved Solids

collecting tank if other water, such as makeup, is received in the tank. The equipment required for this test is as follows: One 100-ml beaker, marked at 50 ml One 1-oz indicator bottle, with dropper marked at 0.5 ml One 4-oz brown bottle of condensate pH indicator One 9-in. stirring rod, glass In making a test for pH of treated condensate, proceed as follows: 1. Pour a freshly drawn sample into the testing beaker until it is filled to the 50-ml mark. You do not have to cool the sample. 2. Transfer 0.5 ml of indicator solution to the 50-ml testing beaker, using the marked dropper. Stir the solution in the beaker. If the color of the solution changes to light pink. the sample is NEUTRAL, or slightly alkaline; therefore, the condensate pH is satisfactory and the test is over. 3. Record in a log that the pH range is between 7 and 7.5. 4. When the color change is green, the sample is in the acid range and the boiler water must be treated with Amines. Treat the boiler water with Amines gradually (in small amounts at a time), and retest after each treatment. Amines are the only chemicals used to treat boiler water that will vaporize and leave with the steam and thereby protect the return system. WARNING Permission to treat with Amines must be obtained from your supervisor. Amines are volatile, poisonous, and in the alkaline range. 6. When the color change is red or purple, the sample is in an excessive alkaline (pH) range. In that case, reduce the Amines treatment gradually (in small amounts at a single time), and retest after each treatment. Remember, the condensate pH normal acceptable range is between 7 and 7.5. Test for Total Dissolved Solids The solu-bridge method is a simple and rapid way to determine the total dissolved solids (TDS) content. Ionizable solids in water make the solution conduct electricity. The higher the concentration of ionizable salts, the greater the conductance of the sample. Pure water, free from ionizable solids, has low conductance and thus high resistance. The solu-bridge instrument measures the total ionic concentration of a water sample, the value of which is then converted to parts per million. The solu-bridge test equipment and reagent are furnished by the supplier in a kit. CAUTION The model of the solu-bridge given below is not suitable for measuring solids in condensed steam samples or an effluent of the demineralizing process. A low- conductivity meter is necessary. because of the extremely low solids content of condensed steam and demineralized water. The equipment and reagent are as follows: One solu-bridge, Model RD-P4 or equivalent, for a 105 to 120-volt, 50- to 60-cycle ac outlet. (This model has a range of 500 to 7,000 micromhos/cm.) One polystyrene dip cell, Model CEL-S2. One thermometer, 0°F to 200°F. One 0.1-g dipper for gallic acid. One cylinder, marked at the 50-ml level. Gallic acid powder, 1 lb. Calibration test solution. I qt. The test is made as follows: Without shaking, pour 50 ml of the sample into the cylinder. Add 2 dippers of gallic acid powder and mix thoroughly with a stirring rod. 2. Connect the dip-cell leads to the terminals of the solu-bridge and plug the line cord into a 110-volt ac outlet. Turn the switch ON. and allow the instrument to warm up for 1 minute. 3. Clean the cell by moving it up and down several times in distilled water. Measure the temperature of the sample to be tested; then set the point of the solu-bridge temperature dial to correspond to the thermometer reading. 4. Place the cell in the cylinder containing the 50-ml sample. Move the cell up and down several times under the surface to remove air bubbles inside the cell shield. Immerse the cell until the air vents on the cell shield are submerged. 1-34