How Liquid Level Sensors Work

Level sensors are used to monitor and regulate levels of a particular free-flowing substance within a contained space. These substances are usually liquid, however level sensors can also be used to monitor some solids such as powdered substances. Level sensors are widely used industrially. Cars use liquid level sensors to monitor a variety of liquids, including fuel, oil and occasionally also specialist fluids such as power steering fluid. They can also be found in industrial storage tanks, for slurries, and in household appliances such as coffee machines. Basic level sensors can be used to identify the point at which a liquid falls below a minimum or rises above a maximum level. Many sensors can detail the specific amount of liquid in a container relative to the minimum/maximum levels, to provide a continuous measurement of volume.
There are a number of different types of liquid level sensor used to detect the point level of a liquid. Some types use a magnetic float, which rise and fall with the liquid in the container. Once the liquid, and by extension, the magnet, reach a certain level, a reed magnetic switch is activated. Commonly, there is a switch towards the top and the bottom of the container, allowing detection of minimum and maximum levels of liquid. Many sensors also include a protective shield to protect the magnet from turbulence or interference from direct contact with the liquid.
Another common type of level sensor is known as a Conductive sensor. Only liquids which conduct electricity can be used in this sensor. This type of sensor includes a source of power, usually of a fairly low voltage. At least two electrodes are placed within the container. When a conductive liquid reaches a certain point, it will come into contact with both a longer and a shorter electrode, and thus complete a circuit and activate an internal switch.
Pneumatic sensors are also a fairly common occurrence with particularly hazardous liquids, or in systems where the use of electricity is not viable or possible. This is because the sensor itself does not come into direct contact with the liquid at all. The sensor detects the level of air between the liquid and the pneumatic sensor, then uses this to calculate the amount of liquid used to fill the remainder of the container. These types of sensors are also relatively cost-effective.
There are also other types of level sensors which offer continuous measurement of liquids. Magnetostrictive sensors are similar in design to regular magnetic float sensors, yet the magnet level is measured using a magnetostrictive wire, which will react when its magnetic field is interrupted by the presence of the magnet. The exact point at which this interruption occurs can be determined by the distance between the bottom of the wire and the point of interference. Alternatives to this design include a magnetoresistive sensor, whereby an additional magnet is inserted onto the arm of the float, allowing accurate triangulation of the exact position of the magnets. This type of sensor is commonly used in conjunction with computer programs due to its accuracy.
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LuminOx Fluorescence Optical Oxygen Sensor With Evaluation Interface Board

LuminOx Fluorescence Optical Oxygen Sensor (O2 Sensor) - LOX-02

LOX-02 LuminOx Fluorescence Optical Oxygen Sensor (O2 Sensor) description
The LuminOx Family is a range of factory calibrated optical sensors which measure ambient O2 levels using the principle of fluorescence quenching by oxygen.
Our unique patented process allows us to produce an oxygen sensor that benefits from low power, traditionally associated with electrochemical sensing devices, while providing a much longer lifetime due to the non-depleting sensing principle.
LuminOx unlike other sensor technologies is stable and robust, it is RoHS compliant as it does not contain lead or any other hazardous materials and has negligible cross sensitivity.
LuminOx can be purchased as a single optical sensor, or as part as an evaluation kit which includes the LuminOx Sensor Evaluation Interface Board, which was designed to allow customers to easily evaluate the sensor with minimum effort or design work. 


LOX-02 LuminOx Fluorescence Optical Oxygen Sensor (O2 Sensor) BENEFITS
• Low power
• Can also measure O 2 % & barometric pressure
• Suitable for battery power use
• Long life
• High accuracy
• Small & compact
• Low cost
• Maintenance free
• Contains no hazardous materials
• Connects directly to microcontroller without any additional circuitry.
• Factory Calibrated

LOX-02 LuminOx Fluorescence Optical Oxygen Sensor (O2 Sensor) APPLICATIONS
• Oxygen Detection
• Portable Equipment
• Breathing Apparatus
• Inerting
• Medical
• Lab Equipment
• Agriculture
• Incubation
• Fire Prevention
• Flue Gas in Condensing Boilers

LuminOx Optical Oxygen Sensor Evaluation Interface Board - LOX-EVB

LOX-EVB LuminOx Optical Oxygen Sensor Evaluation Interface Board GENERAL DESCRIPTION
The LuminOx Sensor family is a range of factory calibrated oxygen sensors which measure ambient ppO₂ levels using the principle of fluorescence quenching by oxygen.
The LuminOx Evaluation interface Board has been designed to allow customers to quickly and easily evaluate the sensor with the minimum of effort or design work
The LuminOx Evaluation Kit simultaneously provides three outputs;
• RS232 (serial interface voltage levels)
• RS485 (Modbus RTU) port allows multiple sensors to be addressed on a bus
• 0-5V Analogue output for basic measurements of oxygen only

LOX-EVB LuminOx Optical Oxygen Sensor Evaluation Interface Board BENEFITS
• Converts the LuminOx TTL level
• RS232 output into 3 standard industrial outputs
• Auto detects ppO2 or O2% variants of LuminOx Sensor.

LOX-EVB LuminOx Optical Oxygen Sensor Evaluation Interface Board APPLICATIONS 
• Oxygen Detection
• Portable Equipment
• Breathing Apparatus
• Inerting
• Medical
• Lab Equipment
• Agriculture
• Incubation
• Fire Prevention
• Flue Gas in Condensing Boilers

LOX-EVB LuminOx Evaluation Interface Board ELECTRICAL AND ENVIRONMENTAL SPECIFICATION

Supply Voltage (Vs)	4.75-5.25 Vdc
Supply Current (Is)	<50mA
Output Types	RS232, RS485 and 0-5V
Operating Temperature	0°C to +50°C
Storage Temperature	0°C to +60°C

LOX-EVB LuminOx Evaluation Interface Board PERFORMANCE SPECIFICATION

LuminOx Sensor Compatibilit	0-25% (O2 % version) 0-300mbar (ppO2 version)
Resolution	0.01% / 0.1mbar (Digital Outputs) 0.01V (0-5V Analogue Output)

LOX-EVB LuminOx Optical Oxygen Sensor Evaluation Interface Board MECHANICAL

Connection	9 Screw terminals
PCB Dimensions	75x55mm max

The LuminOx range has been designed as an alternative to electrochemical sensors but with the benefits of RoHS compliance, long life and complete environmental compensation built-in.

The sensor is available with and without a built-in barometric pressure sensor. LuminOx’s native measurement is partial oxygen p ressure (ppO2) in mbar. By incorporating a barometric pressure sensor, LuminOx is able to measure O2 vol. % in addition to ppO2

Unlike electrochemical sensors, LuminOx requires no additional signal conditioning circuitry and connects directly to the customers microcontroller via 3.3V-level RS232 link. This reduces costs and simplifies system design.

Rain Collector Sensor - Rainfall Sensor

Rain Collector Sensor Rainfall Sensor
This self-emptying, tipping bucket style rain collector utilizes an 8" diameter openning to meet NWS specifications for statistical accuracy. Rainfall is gathered in the collecting bucket and funnels through a small openning into a tipping mechanism. When the mechanism has 1/100th of an inch of water in it, it tips.  A count is then transmitted to an indicator and the water emptys from the tipping mechanism, through the bottom of the collector bucket to the outside.

Rain Collector Sensor Rainfall Sensor
Tipping bucket, self-emptying rain collector.  8" diameter openning meets NWS specifications for size and accuracy.
Dimensions: 8.63" O.D. x 7.88" Deep
Weight: 1.77 lbs.

The rainfall collector requires no manual emptying. Each tip of the bucket is equivalent to 1/100th of an inch of rain. It utilizes a normally open circuit that is momentarily closed each time it tips.  As such, it can be connected to any simple counting circuit, including Maximum's Rainwatch indicator.

Rain Collector Sensor Rainfall Sensor Features
Outside rainfall collector meets NWS specifications for size and accuracy, and is self-emptying for your convenience.
The collector bucket can remain outdoors year-round.  Freezing weather will not damage the collector, but readings of snow or freezing rain are not to be considered accurate readings of rainfall.
Ships complete with 60', 22 AWG, 2-wire, UV protected cable.

Rain Collector Sensor Rainfall Sensor Specifications 
* Type: Tipping bucket, self-emptying
* Dimensions: 8.63" O.D. x 7.88" Deep
* Weight: 1.77 lbs.
* Cable: 60', 22 AWG, 2-wire, UV protected
* Collector Diameter: 8.00"
* Collector Height: 8.00"
* Mounting Diameter: 9.60"
* Housing Materials: ABS Plastic
* Housing Color: Dark Green or Black
* Accuracy: +/- 1% at rates of rainfall up to 1" per hour if collector is properly maintained.
* Required Maintenance: Keep the collecting area and screen free of debris (leaves, branches, etc.). Glean the tipping bucket surfaces and the external surfaces of the collector occasionally with a mild detergent.
* Counting Mechanism: Self-draining, tipping bucket design. The mechanism is factory calibrated so that it automatically tips every 0.01" when installed on a level surface. As the bucket tips a magnet passes back and forth in front of a reed switch. The reed switch is activated as the magnet passes by causing a normally open circuit to be closed momentarily. Each time the circuit is closed the digital readout counts up 0.01".
* Electrical Characteristics :
     Switched current: max 500 mA
     Switched voltage: max 200 VDC
     Contact Resistance: max 100 mOhm
     Contact Capacitance: max 0,25 pF