Level Controller Selection Criteria ■ Categories (Reference Information) Categorized by Fluid Types Applicable liquids Electrode Acid/alkaline solutions Select electrodes based on corrosion resistance Table 4. (Separators are not used.) Electrode Holders Relay Unit Electrodes in BS-IT are outlined in Table 4. Separate each electrode with insulation. Low-sensitivity 61F-@@ND Level Controller (61F-11ND or equivalent, however depending on the cable length, the long-distance 61F-11NL Level Controller may be required.) Boiler SUS316 (The materials used make the BS-1 (Subject to high temperature and Standard 61F-@@ Level Controller water alkaline.) pressure.) Tap water SUS304, SUS316 PS, BF. No other specific requirements. Standard 61F-@@ Level Controller, but when it is over a long distance, use a long-distance 61F-@@L Level Controller. Pure water Titanium (Maintains the purity level of (Ion-exchanged water) water.) BS-1T Titanium May require a high-sensitivity Level Controller depending on conductivity 61F- @@NH (61F-11NH) Ultra-high-sensitivity 61F-UHS Level Controller Bubbles (Detection) PS, BF High-sensitivity 61F-GP-NH Level Controller or equivalent Bubbles (No detection) As above (Separators are not used.) As above Low-sensitivity 61F-@@ND Level Controller Wastewater SUS304 (Low salinity) (Separators are not used.) BF-1 is used with each electrodes separated. Low-sensitivity 61F-@@ND Level Controller Oil mixed in water SUS304 PS, BF use pipes to guard against the Standard 61F-@@ Level Controller oil. Steam SUS316 PS-1, BF-1 Standard 61F-@@ Level Controller If there is enough pressure to be able to separate the electrodes, use the BS-1. SUS304, SUS316, Titanium (Separators are not used.) Categorized by Installation Conditions of Electrodes Installation Condition Confined space Electrode PH underwater electrodes Electrode Holder --- Protect against rainwater SUS304, SUS316 PS + F03-11 Protective Cover + F03-12 Frame Objects from wastewater (i.e., clothing) get tangled SUS304 The BF-1; separates the distance between electrode holders Wastewater, contaminated water, or areas with SUS304 or SUS316 clusters of grease As above Elevated tank SUS304 or SUS316 PS Ground tank SUS304 or SUS316, F03-05 Electrode Band, PH underwater electrodes PS Sewer, drains (manhole) SUS304, SUS316 PS (Place the electrodes in a pipe in areas that accumulate grease, e.g., underground, factory pits) Septic tank (Flushed matter) SUS304 BF-1 Measurements at a depth like water wells PH underwater electrodes --- Areas where ice forms PH underwater electrodes --- High temperature (hot water tank) SUS316 Temperatures under 50°C, BS-1S2 No model is suitable for temperatures above 250°C (Must be made by the user.) 8 ■ Selection Criteria for 61F Level Controllers Specific Resistance and Model Selection Criteria The limit for specific resistance of liquid that can be controlled with a generic Level Controller is 30 kΩ·cm when using a PS-3S Electrode Holder within a submersion depth of 30 mm. For any fluid with specific resistance higher than this value, use a high-sensitivity Level Controller (H type). (See note.) Table 1 and Table 2 shown on the right and Table 3 on the next page show specific resistances for typical liquids. Use these when selecting a model. Note: 1. The high-sensitivity Level Controllers may suffer from resetting problems when used with certain types of water. In some cases it cannot substitute for the standard Level Controllers or Low-sensitivity Level Controllers. Be sure to select the model appropriate for the application. 2. The circuit configuration of the High-sensitivity 61F-@H Level Controller is designed so that the relay is reset when there is water present between the electrodes. When power supply voltage is applied, the internal relay switches to the NO contact and, when there is conductivity between electrodes E1 and E3, the relay is reset to the NC contact. This contact operation is reversed for models other than the high-sensitivity models. Although the internal relay operates (and operation indicator turns ON) simply when the power supply voltage is applied, this operation is normal. (The relay in the 61F-@NH energizes when there is water present between the electrodes.) Conductance Conductance is a scale describing how easily current can flow. The relationship of conductance and resistance is defined by the following equation. Conductance = 1 (siemens: S) Resistance (Ω) Table 1 can be modified to contain the corresponding conductance as shown in Table 1A. Table 1A: Specific Conductance of Water (Guideline) Type of water Tap water Specific Conductance 100 to 200 µS/cm Well water 200 to 500 µS/cm River water 67 to 200 µS/cm Rainwater 40 to 67 µS/cm Seawater 33,300 µS/cm Sewage 500 to 2,000 µS/cm Distilled water 3.3 to 4 µS/cm max. Note: For the ultra high-sensitivity variable 61F-HSL Level Switch, malfunction due to electric corrosion may occur in the DC electrode circuit. Be careful not to use the product where current constantly flows between electrodes. Table 1: Specific Resistance of Water (General Guideline) Type of water Specific resistance Tap water 5 to 10 kΩ·cm Well water 2 to 5 kΩ·cm River water 5 to 15 kΩ·cm Rainwater 15 to 25 kΩ·cm Seawater 0.03 kΩ·cm Sewage 0.5 to 2 kΩ·cm Distilled water 250 to 300 kΩ·cm min. Table 2: Detectable Specific Resistance (Guideline) Type of use Long distance (4 km) Specific resistance (recommended value) 5 kΩ·cm max. Long distance (2 km) 10 kΩ·cm max. Low sensitivity 10 kΩ·cm max. Two-wire 10 kΩ·cm max. General-purpose 10 to 30 kΩ·cm High-temperature 10 to 30 kΩ·cm High-sensitivity (COMPACT plug-in type) 30 to 200 kΩ·cm High-sensitivity (base type) 30 to 300 kΩ·cm Ultra high-sensitivity 100 kΩ to 10 MΩ·cm Note: The specific resistance of liquids are those that can be controlled using the PS-3S when the submersion depth is 30 mm or less. 9 Table 3: Specific Resistance of Various Liquids Type of liquid Temperature (°C) Concentration (%) Specific resistance (Ω·cm) Beer (Company A) Port wine (Company K) Whisky (Company T) Sake (Company K First grade quality) 12 12 12 12 --------- 830.0 966.0 14,608.0 1,743.0 Silver nitrate AgNO3 18 5.0 60.0 39.5 4.8 Barium hydroxide Ba (OH)2 18 1.25 2.5 40.0 20.9 Calcium chloride CaCl2 18 5.0 20.0 35.0 15.6 5.8 7.3 Cadmium chloride CdCl2 18 1.0 20.0 50.0 181.0 33.5 73.0 1.0 5.0 35.0 240.0 68.5 23.8 Cadmium sulfate CdSO4 18 Nitric acid HNO3 18 15 15 5.0 31.0 62.0 3.9 1.3 2.0 Phosphoric acid H3PO4 15 10.0 60.0 87.0 17.7 5.5 14.1 5.0 30.0 97.0 99.4 4.8 1.4 12.5 117.6 Sulphuric acid H2SO4 18 Potassium bromide KBr 15 5.0 36.0 14.5 2.9 Potassium chloride KCI 18 5.0 21.0 14.5 3.6 Potassium chlorate KClO3 15 5.0 27.2 Potassium cyanide KCN 15 3.25 6.5 19.0 9.8 Potassium carbonate K2CO3 15 5.0 30.0 50.0 17.8 4.5 6.8 Type of liquid Temperature (°C) Concentration (%) Specific resistance (Ω·cm) Copper sulfate CuSO4 18 2.5 17.5 92.6 21.8 Ferrous sulfate FeSO4 18 0.5 3.0 65.0 21.7 Hydrogen bromide HBr 15 5.0 15.0 5.2 2.0 Hydrochloric acid HCl 15 5.0 20.0 40.0 2.5 1.3 1.9 Hydrogen fluoride HF 18 0.004 0.015 0.242 298.0 4,000.0 2,000.0 275.0 2.9 Mercuric chloride HgCl2 18 0.229 5.08 22,727.0 2,375.0 Hydrogen iodide HI 15 5.0 7.5 Potassium sulfate K2SO4 18 5.0 10.0 21.8 11.6 Sodium chloride NaCl 18 5.0 25.0 14.9 5.6 Sodium carbonate Na2CO3 18 5.0 15.0 22.2 12.0 Sodium iodide NaI 18 5.0 40.0 33.6 4.7 Sodium nitrate NaNO3 18 5.0 30.0 22.9 6.2 Sodium hydroxide NaOH 15 2.5 20.0 42.0 9.2 2.9 8.4 Sodium sulfate Na2SO4 18 5.0 15.0 24.4 11.3 Ammonia NH3 15 0.1 4.01 3.05 3,984.0 913.0 5,181.0 Ammonium chloride NH4Cl 18 5.0 25.0 50.5 2.5 Ammonium nitrate NH4NO3 15 5.0 50.0 16.9 2.7 Potassium fluoride KF 18 5.0 40.0 15.3 4.0 Ammonium sulfate (NH4)2SO4 15 Potassium iodide KI 18 5.0 55.0 31.4 2.4 5.0 31.0 18.1 4.3 Zinc chloride ZnCl2 15 Potassium nitrate KNO3 18 5.0 22.0 22.1 6.2 2.5 30.0 60.0 36.2 10.8 27.1 Potassium hydroxide KOH 15 4.2 33.6 42.0 6.8 1.9 2.4 Zinc sulfate ZNSO4 18 5.0 30.0 52.4 22.5 Potassium monosulfide K2S 18 3.18 29.97 47.26 11.8 2.2 3.9 10 ■ Selecting Electrode Material According to Resistance against Corrosion To get the most out of the electrodes, refer to Table 4 to select the best material. Table 4: Resistance to Corrosion of Electrode Material Aqueous Solution Type Electrode material Aqueous Solution Concen- Temper- SUS SUS Tita- HAS HAS C tration ature 304 316 nium B (%) (°C) Type Electrode material Concen- Temper- SUS SUS Tita- HAS HAS C tration ature 304 316 nium B (%) (°C) Sulphurous acid H2SO3 6 30 E C A B B 5 to 50 RT A A A A A Sulphuric acid H2SO4 1 30 A A A A A 100 RT A A A A A 1 BP E D E B C 100 BP C B A A A 3 30 B A A A A Formic acid H·COOH All BP D D D A A 3 BP E E E C C Acetone CH3·CO·CH3 All RT B B A A A 5 30 D B D B A Alum All RT E E D B B Hydrochloric acid HCl Chromium oxide CrO3 Nitric acid HNO3 Hydrogen fluoride HF Phosphoric acid H3PO4 Acetic acid CH3COOH 5 BP E E E D D Aluminum sulfate 50 BP D C B C A 10 30 E C E A A 5 BP D D A B B 10 BP E E D C E Ammonium chloride NH4Cl 20 30 E E C C B Ammonium nitrate NH4NO3 All BP A A A B B 20 BP E E D D E RT E D B B C 30 E E D B B Ammonium sulfate (NH4)2SO4 5 40 10 BP E E B B C 40 BP E E D E E Ammonia NH3 100 100 C C A B B 60 30 E E D B C 60 BP E E D C D 70 30 E E D B B 70 BP E E D C D Potassium hydroxide KOH 80 30 E E D B 80 BP E E D D 90 30 E E D B B 90 BP E E D D D 95 30 E D D B 95 BP E E D 1 30 E D B 1 BP E E 3 30 E E 3 BP E E E 5 30 E E C 10 BP C B B B C 28 60 C B A B B 25 BP B A C B C B Sodium hydroxide NaOH 30 60 A A B A B D 50 65 B A C A C Sodium carbonate Na2CO3 25 BP B B B B B B Potassium carbonate K2CO3 20 BP B B B B B D D Zinc chloride ZnCl2 50 150 D C B B C B A Calcium chloride CaCl2 25 BP C C A A A E D C Sodium chloride NaCl 25 BP C B A B B B B A Ferric chloride 30 RT E E A E B D C Copper chloride 30 C A Sea water RT E E A E B RT C C A B A 5 BP E E E E D Hydrogen peroxide H2O2 10 RT B B B B B 10 30 E E E C C Sodium sulfite 10 RT B B A B B 10 BP E E E E E Citric acid All RT B A C A A 15 30 E E E C C Oxalic acid CO2H·CO2H All RT B A D B B 15 BP E E E E E Sodium hypochlorite 10 RT E D A C C 20 30 E E E C D Potassium dichromate 10 BP C B A B C 20 BP E E E E E Magnesium chloride 30 RT C B A A A 37 30 E E E C E Magnesium sulfate 10 RT B B A A A 37 BP E E E E E 10 BP D C A B C 20 30 C B A B B 36.5 90 E E C C C 10 30 B A A D A 10 BP B B B D C 20 290 B B C D D 65 175 C C B E E 68 30 C C A D D 68 BP D D B E E 90 80 E E A E E 5 30 E E D D C 100 30 E D C C C Note: 1. RT: Room temperature BP: Boiling point 2. A: Adequate resistance to corrosion B: Resistive to corrosion, erosion rate is less than 0.8 mm/year C: Low resistance to corrosion, erosion rate is less than 1.8 mm/year D: Highly corrosive, not usable E: No resistance to corrosion, not usable 3. The table above is used for reference when selecting the electrodes. Even if the material has adequate corrosion resistance, it doesn't mean that it is not subject to corrosion. Check regularly once a month to see if corrosion is occurring. If it is, replace the electrodes. 10 to 85 RT B B C B C Reference When selecting an Electrode Holder, make sure that you consider the corrosion resistance of the material of electrode holders as it may be exposed to the liquid inside the water tank. 11