8 Level Controller Selection Criteria

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 [email protected]
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 [email protected] 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