Industrial Data Collection
Analysis and Control
Madison
Fluid Sensing Solutions
Optical Level Sensors:
Miniature Optical Liquid Level SensorWet Sensing for 5-12 VDC
- Detects high/low levels in a container
- Can sense clean, non-coating liquids
- Stable under continuous use in hot water / steam
- Temperatures up to 257°F.
Miniature Optical Liquid Level SensorWet Sensing for 10-45 VDC
- 316 Stainless Steel
- Can sense a variety of clean, non-coating liquids
- Ideal for high-temperature applications
- Suitable where corrosion resistance is required
Miniature Optical Liquid Level SensorWet Sensing for 5-12 VDC
- Stable in water or steam at temps up to 257°F.
- Can sense a variety of clean, non-coating liquids
- Detects high/low levels in a container
- Dairy connectors, manifolds, steam-cleaning equipment
Miniature Optical Liquid Level SensorWet Sensing for 8-30 VDC
- Input supply of 8-30VDC for industrial applications
- Can sense a variety of clean, non-coating liquids
- Stable in water or steam at temps up to 257°F
- Analytical instrumentation, medical devices
Miniature Optical Liquid Level SensorWet Sensing for 5-12 VDC
- Stable in water or steam at temps up to 257°F
- Can sense a variety of clean, non-coating liquids
- Input supply of 8-30VDC for industrial applications
- Medical devices and semiconductor process equipment
Optical Level Sensor Application Notes:
N & P-Channel Open Drain Push-Pull Output
To rest of LL Sensor circuit
Additional reverse protection diode recommended when switching larger relays or inductive loads to protect the sensor from spikes.
Push - Pull High in Air - Equivalent Circuit:
Push - Pull Low in Air - Equivalent Circuit:
| Protection Techniques and Common Failure Modes | |||||
|---|---|---|---|---|---|
| Load | Load Example | Protection | Diagram | Common Failure Modes | Failure Mode Description |
| Resistive (DC) | Indicator Lamp, Heaters | Current Limiting Resistor | In-rush Current (Switching) | In-rush current exceeds rating and welds switch closed | |
| Over-Current (Carry) | Carry-current exceeds rating and switch welds or burns open like a fuse | ||||
| Inductive & Capacitative (DC) | Relay Coil, Solenoids, Motor | Reversing Diode | Over-Voltage (Arcing) | Voltage arcing during switching weldscontacts closed | |
| Inductive & Capacitive (AC or DC) | Resistor & Capacitor Network | ||||
| Resistive, Inductive & Capacitive (AC or DC) | Indicator Lamp, Heaters, Relay Coil, Solenoids, Motor | Varistor or MOV | Over-Voltage (Arcing) | Transients voltage spikes exceed breadown voltage and weld switch closed | |
RFQ:
Reed Switch Protection
Our level switches utilize reed switch technology, which are glass encapsulated, magnetically actuated switches. Madison generally provides electrical ratings for resistive loads; however, where the maximum current of the load permits, the switches are capable of controlling devices such as motors, solenoids or coils that produce capacitive or inductive electrical loads. Where possible, Madison recommends the use of general-purpose/isolation relays or controllers to protect the switch.
The life of the reed switch ranges from 106 to 109 operations, dependent upon load conditions. The special reed blade material is selected to ensure a mechanical life of at least 3 x 109 operations.
| Current and Voltage Rating of Liquid Level Switches | |||||
|---|---|---|---|---|---|
| UL Rating of Level Switch | Madison Calculation | ||||
| Nominal VA | Amperes (resistive) at 240 VAC | Amperes (resistive) at 120 VAC | Amperes (resistive) at 120 VDC | Amperes (resistive) at 24 VDC | Amperes (resistive) at 12 VDC |
| 360 | 1.50 | 3.00 | 0.75 | 3.00 | 3.00 |
| 100 | 0.40 | 1.00 | 0.40 | 1.00 | 2.00 |
| 60 | 0.40 | 0.50 | 0.20 | 0.50 | 0.70 |
| 30 | 0.14 | 0.28 | 0.07 | 0.28 | 0.56 |
| 25 | n/a | 0.28 | n/a | 0.28 | 0.28 |
| 15 | n/a | 0.12 | 100 VDC / 0.10 | 0.30 | 0.30 |
Above ratings are for resistive loads only.
Maximum voltage ratings:
SPST Switches – 240 VAC;
SPDT Switches – 120 VAC
Nominal VA is Volts x Amps and is the term used for Apparent Power in AC circuits. It is simply the product of voltage and current, without taking into account the type of load (resistive or inductive). In this chart we use the Nominal VA with resistive load in conjunction with the applied AC voltage to determine the current – we are stating currents with a resistive load. Watts and VA can be used interchangeably in the charts above.
We recommend that switches stay below these ratings for non-resistive loads. Current and Voltage ratings are for resistive loads only. For inductive loads, maximum life will be achieved if appropriate arc suppression is used.
Each switch has a power rating in watts. These power ratings are for resistive loads that are at a steady state and are calculated as Power (Watts) = Voltage (AC/DC) * Current (Amps-resistive load). Most devices have other things to consider, such as current or voltage spikes caused when powering up or shutting down. Common devices such as pumps, coils and light bulbs can create these types of spikes. For these more complex cases, one must remember to stay within the maximum current and voltage ratings of the switch regardless of the power rating.
Our 30-watt standard switches have a maximum switching current of 1 Amp and a carrying current of 2.5 Amps. If the switch is connected to a 12 V circuit that spikes to 2 Amps and runs at a steady state of 1 Amp, the power spike exceeds the switch rating although the steady state running power is 12 Watts. Due to the heat and type of power dissipated during the spike, the contact may be damaged or even welded together, causing switch failure.
Custom designs have other elements to consider and even alternative ground paths that may affect the power delivered to a switch. It is important to consult your engineering department before assuming the system's power requirements.
Madison point level float switches use reed switch technology that is simple, reliable, and durable. They operate in an on/off state, and are used to control an external device such as an alarm or an on/off switch. Because OEMs need sensors for tanks that vary in width and height, certain point level float switches are offered with field-adjustable stem lengths. This provides an OEM with the advantage of using only one or two sensors for their application instead of several.
| Acetic acid - Glacial | Acetic acid - 10% |
| Ammonia - 88 | Ammonium Hydroxide |
| Benzene | Benzoic acid |
| Bleach | Brine |
| Butane | Calcium Nitrate |
| Calcium Hyphochlorite | Copper Sulphate |
| Creosote | Cyclohexane |
| Cyclohexanol | Detergent solutions Diesel fuel Diethylamine |
| Diethyl Ether | Dioctyl Phthalate Edible fats & oils Ethanol 50% |
| Ethyl Alcohol Ethylene Glycol | Ferric Chloride Formaldehyde |
| Formic acid | Glycerol |
| Heptane | Hydrochloric acid |
| I so-Octane | Kerosene |
| Linseed oil | Magnesium Sulphate Methanol |
| Motor oil | Nitric acid 10% |
| Oils - Vegetable | Oxalic acid |
| Petroleum Ether | Silver Nitrate |
| Soap solution | Sodium Chloride |
| Sodium Hydroxide | Varnish |
| Water | White Spirit |
| Acetone | Methanol |
| Benzene | Mountain pine oil |
| Break Free (lubricating oil) Carbon tetrachloride | Petroleum ether |
| Diesel fuel | Potassium hydroxide |
| Econa PG32 (Hydraulic fluid) Ethanol | 1,2-propane dial |
| Ethyl acetate | Regular gas |
| Eucalyptus oil Formaldehyde solution Glycerine (DAB6) | Test fuel (M15) |
| Heating oil | Toluene |
| lsopropanol | Xylene |