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Level Switch – Common Applications and What are they used for?

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Optical Level Switch - Common Applications and What are they used for?

The Optical Liquid Level Switch is a solid-state technology which uses an infra-red LED and phototransistor to detect the presence or absence of liquid. In this article, we will cover what the level switch is used for and the types of applications they are commonly used in.

What is an optical liquid level switch used for?

An optical liquid level switch is used to detect the presence or absence of almost any type of liquid, oil or water based. The main purpose for these level switches fall into two main categories; leak detection and single point level control (maximum or minimum).

For a relatively low-cost solution, the purpose of these switches can prevent many disastrous and expensive situations. In leak detection applications they can detect the smallest amounts of liquid to prevent loss of valuable fluids, run dry situations, expensive damage, loss of service and downtime. In level control applications they are used for automated refilling for low and high-level liquid level processes. The switches can prevent overspill or run dry situations.

Optomax LLG

Common Applications

As mentioned above, the type of applications falls into two main categories; leak detection and level control. The number of leak detection and level control applications SST are confronted with each day is endless, however we have detailed below the most common types we are asked about. If your application is not listed below, please contact us and we will be happy to discuss your requirements.

Leak Detection

Telecommunications

Detecting rainwater leaks at an early stage in outdoor telecommunication units and so preventing loss of service or potentially expensive damage is an application SST is very familiar with. The increased use of small and metrocell technology has resulted in a growing number of telecommunication enclosures being deployed in locations which are difficult to access and not subject to regular inspection.

With the level switch being able to detect very small amounts of liquid, it is an ideal solution for this application as it is mounted at the bottom of the enclosure in a small sump, if there is rainwater present, a signal is sent to advise action to be taken.

Telecom Tower

Robotic Automation Systems

Industrial robotic systems is another application in which SST has a lot of experience with. Industrial robots are hugely expensive to install to is crucial that they are operated and maintained correctly – any “down-time” can be costly.

Oil within the system is used to lubricate the joints and gears and prevent overheating, misalignment, and bearing wear. If this oil leaks during operation, it could contaminate the surrounding environment, damage production and affect machine performance. Immediate detection of when an oil level is low is therefore critical to avoid costly expense.

Robotic Arm

Peristaltic Pumps

Peristaltic pumps are suitable for dispensing, metering and general transfer of liquid media. They confine the media to the tubing, so that the pump cannot contaminate the fluid and the fluid cannot contaminate the pump. The contamination-free pumping makes peristaltic pumps particularly suitable for use in high purity applications, including the transfer or dosing of chemicals and additives in the food, pharmaceutical and semiconductor industries.

The level switches are mounted at the bottom of the pump in a sump to capture any leaking fluid from the tubing which then alerts the system to stop the pump from running. The installation of the level switch provides two key benefits; the first is it protects against the loss of high value fluid, and prevents costly damage to the pump.

Peristaltic Pump

Single Point Level Control

Tank or Vessel Level Control Monitoring
aviation
AdobeStock_132802484_400x400_acf_cropped

In level control and detection applications, the liquid level of a tank or vessel will vary at a continuous pace over a period. In order to know when failure occurs of when the level goes dangerously high or low, it is critical to have a level control monitoring solution in place to prevent expensive damage, flooding or run dry situations.

The level switch is used by various industries as a level indicator. Industries include industrial, domestic, medical, marine, aviation and transportation. Common level detection and level control applications that SST have had experience with over the years are;

For high/low level indication;

–          Hydraulic fluid

–          Water storage tanks

–          Transmission fluid

–          Off-road vehicles and machinery

–          Submarine torpedo tubes and water separators

–          Dialysis machines

–          Testing machinery for electrical protective gloves

–          Water level in neonatal incubator

For automated refilling, low/high level processes in;

–          Medical

–          Process control

–          Domestic products

–          Food and beverage applications

–          Fluid levels in off-road vehicles, aircrafts and static equipment

For more information on SST’s optical liquid level switches, please contact us below.

SST Launch Range of Low Power, High Speed CO2 Sensors

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SST Launch Range of Low Power, High Speed CO2 Sensors

SST is delighted to announce their launch of market leading CO2 Sensors that integrate unique mid infra-red light source and detector technology into innovative optics and signal processing. The three product ranges are designed to fit into various types of applications in a range of markets and industries.

CozIR® Range

The CozIR® range of CO2 Sensors are designed to monitor CO2 in “breathable” ambient air up to 10,000ppm. Ideally suited for CO2 monitoring in buildings, offices or outdoors. The CozIR® range of CO2 sensors are typically consume 50 times less power than standard NDIR sensors on the market today.

Carbon Dioxide sensors

ExplorIR® Range

The ExplorIR® range of CO2 sensors’ combination of extremely low power consumption and instantaneous warm-up answers directly to the growing demand for sensors which can be integrated into battery or self-powered wireless systems, allowing economical real time monitoring of CO2 concentration levels up to 100% CO2.

Carbon Dioxide sensors

SprintIR® Range

The SprintIR® range of CO2 sensors is designed for applications the require capture of rapidly changing CO2 concentrations and is suitable for measuring concentrations from 0-100% CO2. The CO2 sensors within this product range can take up to 20 readings per second making it the world’s fastest battery-powered NDIR CO2 sensor on the market today.

The core technology is a good fit for a wide variety of applications, markets and industries. This includes air quality & HVAC, healthcare, horticulture & food processing, transportation, industrial safety, and aerospace industries.

Discover more about our CO2 Sensors.

Cyber Essentials Certification

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Cyber Essentials Certification

SST Sensing Limited achieves certification in Cyber Security.

SST Sensing are pleased to announce compliance with the UK governments National Cyber Security Strategy with systems certified to comply with the Cyber Essentials Scheme.

A primary objective of the UK Government’s National Cyber Security Strategy is to make the UK a safer place to conduct business online.

By deploying these controls, organisations can defend against the most common form of basic cyber-attacks originating from the Internet.

The Cyber Essentials scheme identifies some fundamental technical security controls that an organisation needs to have in place to help defend against Internet-borne threats.

Cyber Essentials is a UK government scheme encouraging organisations to adopt good practice in information security. It includes an assurance framework and a simple set of security controls to protect information from threats coming from the internet.

It was developed in collaboration with industry partners, including the Information Security Forum (ISF), the Information Assurance for Small and Medium Enterprises Consortium (IASME) and the British Standards Institution (BSI), and is endorsed by the UK Government.

The five main technical controls are:

  • Boundary firewalls and internet gateways
  • Secure configuration
  • Access control
  • Malware protection
  • Patch management
Click here for SST's Cyber Essentials Certificate

Types of Interface Boards to Operate Zirconia O2 Sensors

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What Types of Interface Boards Can You Use With SST Zirconia O2 Sensors?

In order to operate any of SST’s Zirconia O2 Sensors, you will require an interface board which provides the electronics necessary to power and control the zirconium dioxide oxygen sensors.

Alternatively, if you would rather have a complete solution, have a complete solution, the Oxygen Measurement System, OXY-Flex or OXY-Comm may better suit your needs. When choosing the option you require, you should consider the following;

  1. O₂ measurement range; 0.1-25% or 0.1-100%
  2. Output requirements; digital (RS485 Modbus or RS232) or analogue (4-20mA or 0-10Vdc)
  3. Location; cable length is important; to maintain the correct sensor heater voltage and minimize noise pick up, SST recommends keeping the cable length between the sensor and interface board as short as possible.
  4. Convenience; do you want an “off-the-shelf” solution or configure the equipment yourself? If you want to design the board yourself. Please refer to our Zirconia Sensor Software and Hardware Design Guide

Types of Interface Boards

There a number of options available which enable you to power and control SST’s range of zirconium dioxide o2 sensors; interface board or a complete solution. The following gives a brief overview of each type of interface PCB.

OXY-LC Interface

The OXY-LC Interface Board has a built-in pressure sensor for barometric pressure compensation and offers the following specifications;

  • Supply voltage: 8 to 28Vdc (RS485 variant) or 20 to 28Vdc (analogue variants)
  • O₂ measurement range: 0.1 to 100% (RS485 variant) and 0.1 to 25% or 0.1 to 100% (analogue variants)
  • Operating temperature range: -30⁰C to +70⁰C
  • Output options: RS485, 0-10V or 4 to 20mA
  • Termination: PCB screw terminals
o2 probe

O2I-Flex Interface

The O2I-FLEX has externally triggered automatic or manual calibration. Calibration can also be initiated via an on-board push button switch. The O2I-FLEX offers the following specifications;

  • Supply voltage:24Vdc 10%
  • O₂ measurement range: 0.1 to 100% (RS232 variant) and 0.1 to 25% or 0.1 to 100% (analogue variants)
  • Operating temperature range: -10⁰C to +70⁰C
  • Output options: RS232, 0-10V or 4 to 20mA
  • Termination: Removable polarised screw terminals
O2I FLEX

Oxygen Measurement System Complete Solution

The Oxygen Measurement System has a built in pressure sensor for barometric pressure compensation and is used in combustion control including oil, gas and biomass boiler applications.

  • Supply voltage: 8 to 28Vdc (RS485 variant) or 20 to 28Vdc (analogue variants)
  • O₂ measurement range: 0.1 to 100% (RS485 variant) and 0.1 to 25% or 0.1 to 100% (analogue variants)
  • Operating temperature range: -30⁰C to +70⁰C
  • Output options: RS485, 0-10V or 4 to 20mA
  • Termination: PCB screw terminals
Zirconia Oxygen Sensor System

OXY-Flex Complete Solution

The OXY-Flex has externally triggered automatic or manual calibration and has an IP65 rated housing. It is used in combustion control including oil, gas and biomass boiler applications. Long probe lengths are ideal for thicker walled flues.

  • Supply voltage: 24Vdc 10%
  • O₂ measurement range: 0.1 to 100% (RS485 variant) and 0.1 to 25% or 0.1 to 100% (analogue variants)
  • Operating temperature range (electronics): -10⁰C to +85⁰C
  • Gas temperature range (at probe tip): -100⁰C to +250⁰C (standard variant), or -100⁰C to +400⁰C (high temp variant)
  • Output options: RS232, 0-10Vdc or 4 to 20mA
  • Termination: Amphenol Ecomate C016 30C006 100 12
OXY-Flex Oxygen Analyser

OXY-Comm Complete Solution

The OXY-COMM can be calibrated through Modbus. The housing is IP65 rated and also has a built in pressure sensor for barometric pressure compensation. The OXY-COMM is used in refrigerated/controlled atmosphere transportation (“Reefer”) containers. Fire prevention in facilities such as server rooms, or document storage and also protecting historical artefacts against oxidation.

  • Supply voltage: 8 to 15Vdc
  • O₂ measurement range: 0.1 to 100%
  • Operating temperature range: -40⁰C to +60⁰C
  • Output options: RS485
  • Termination: Brad Harrison style 4-pin M12 connector
OXY-COMM

For more information on any of SST’s Zirconia O2 Sensors, interface electronics or complete oxygen sensing solutions, please contact us and to discuss your requirements.

Prolonging the life of your Zirconia oxygen sensor – Helpful hints and tips

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How to get the most out of your Zirconium Dioxide Oxygen Sensor?

This article gives an overview of helpful hints on how to pro-long the life of SST’s Zirconia Oxygen Sensors. The application in which the zirconia oxygen sensor is operating influences the life of the sensor. To ensure the sensor does not fail prematurely, the following hints and tips should be considered:

 

Fail Safe Operation and Sensor Asymmetry

One of the main benefits of the dynamic and active cell employed within the oxygen sensor is that it is inherently fail safe. The continual cycling and measuring of the generated Nernst voltage is effectively the heartbeat of the sensor, if this stops something fatal has occurred within the cell. This can very quickly be detected by the interface electronics

Refer to the Zirconia Sensor Operating Principle and Construction Guide for details.

 

Operating in Aggressive Humid Environments

When operating the zirconia oxygen sensors in warm, humid environments it is important the sensor remains at a higher temperature than its surroundings, especially if there are corrosive components in the measurement gas. During operation this is less of an issue as the heater operates at 700⁰C, however this means when the sensor or application is being powered down the sensor heater must be the last thing to be turned off after the temperature of the surroundings have suitably cooled. Ideally the sensor should be left powered or at a lower standby voltage (2V typically) at all times in very humid environments.

Failure to adhere to these rules will result in condensation forming on the heater and sensing element. When the sensor is re-powered the condensation will evaporate, leaving behind corrosive salts which very quickly destroy the heater and sensing element as illustrated in the image to the left. Note how the sensor’s external metalwork looks completely normal.

Protecting from Excessive Moisture

In environments where excessive moisture or falling water droplets are likely, the sensor should be protected from water reaching or falling directly onto the very hot sensor cap as this can cause massive temperature shocks to the cell and heater. Popular methods include a hood over the sensor cap or for the sensor to be mounted in a larger diameter cylinder.

At a very minimum the sensor cap should be angled downwards in the application as this will deflect any falling moisture and prevent the sensor cap from filling with water.

 

Using the Sensor with Silicone

Zirconia oxygen sensors are damaged by the presence of silicone in the measurement gas. Vapours (organic silicone compounds) of RTV rubbers and sealants are the main culprits and are widely used in many applications. These materials are often made with cheaper silicones, that when heated still outgas silicone vapours into the surrounding atmosphere. When these vapours reach the sensor, the organic part of the sensor will be burned at hot sensor parts, leaving behind a very fine divided Silicon Dioxide (SiO₂). This SiO₂ completely blocks the pores and active parts od the electrodes. If RTV rubbers are used we advise using high quality, well cured materials.

Zirconia Oxygen Sensor with excessive moisture
Zirconia Oxygen Sensors

SST's Zirconium Dioxide Oxygen Sensors

SST’s zirconium dioxide oxygen sensors offer a range of housing styles, cabling and electrical connections.

The sensors can be purchased alone or with integrated electronics offering digital or analogue industry standard outputs.  Their long operating life is due to the non-depleting sensor cell technology. No reference gas is required and easy single point calibration can be performed in any known gas including fresh air. The oxygen sensors can measure over a wide oxygen range (0.1 to 100% O₂).

The reliability of these sensors means that they are used globally in applications ranging from composting to fuel tank inerting in civilian airliners.

What causes Float Switches to fail

What Causes Float Switches to Fail?

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Even although there are various types of level sensing technologies on the market today, many people associate a liquid level sensor with a “float switch”.

For many applications where liquids need to be monitored within a tank or other container, float switches are the most cost effective solution.

There are various types of float switches and they can be configured in a number of different ways. Typically, the way in which a float switch operates uses a magnetic reed switch, breaking or connecting an electrical circuit when liquids reach a designated level.

While these switches are commonly used for tank level applications, they can fail and cause unreliability issues. When failure occurs, it can cause malfunction or costly damage to equipment, proving that not all cost effective measurement methods can save money or time in the long term.

The main causes for failure in this type of float switch is down to three common faults.

  • Poor maintenance
  • Selecting the wrong switch for your application
  • Moving parts

The first is poor maintenance. All float switches require regular maintenance checks in order to prolong the lifetime of the product. If no or very little maintenance is carried out the lifetime is significantly reduced and will cause early failure. It is important to refer to the sensor manual for the recommended maintenance checklist or guidelines.

Poor research can lead to wrong decisions. Many customers often find themselves in a situation where the float switch is failing because it is not suited for the application. Depending on the application, you may need a switch that is made from a different material or a switch that is made with a specific mechanical configuration. Getting the best match between your equipment and your application is without a doubt the best preventative maintenance you can do. The functionality of the switch, environmental and physical factors are all important to consider before making a purchase to ensure the float switch will suit your application requirements.

In many applications the environment can be dirty, corrosive and in some instances hazardous. However, when you are faced with these conditions, it is important to ensure the technology you choose can a) survive when exposed to this environment and b) be a reliable source. More often than not, if no maintenance checks are being carried out on a regular basis, when the switch is exposed to these conditions, debris and dirt often jam in the switches moving parts causing false and unreliable readings.

 

Why Choose Optical vs Float?

Optical liquid level switches is another type of level sensing technology offering a competitive edge over float switches as they are maintenance free and solid state, with no moving parts. Optical liquid level switches are commonly used in tank level measurement applications. They can detect tiny amounts of liquid if positioned correctly, unlike floats where the liquid level has to be substantial before making contact with the switch. They are easy to install, the level switch protrudes very slightly into the wall of the tank with the sensor tip facing inwards. They are small and compact meaning they can be installed where space is limited.  They have a long operating life and low sensitivity to ambient light and robust enough to operate in wide operating temperatures and harsh liquid media.

 

How does the sensor work?

When in air, the infrared light inside the sensor tip is reflected back to the detector. When in liquid, the infrared light is refracted out of the sensor tip causing less energy to reach the detector. The output is either high or low, so they are very simple to understand and operate.

 

For more information on SST’s optical liquid level switches, please Ask our Experts!
Jamie Roberts - Scottish Golf Sponsorship

SST is Delighted to Announce Sponsorship with Scotland’s 16 year old Golfing Star, Jamie Roberts

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Jamie first picked up a golf club aged 9 at the Juniors Night at Muckhart Golf Club in Clackmannanshire where his dad is a member.  As well as enjoying the social side at that age he quickly took to the sport and was a regular at Juniors Night and began living on the golf course during the school summer holidays.

Jamie has reduced his handicap in five seasons from 28 to 1 with the aim of being off scratch by the beginning of next season.

His dream is to become a successful, professional golfer and this is what motivates him each training session and competition.  He receives coaching at Gleneagles and is one of thirteen selected for the Gleneagles Foundation which was set up after the 2014 Ryder Cup to support and develop the next generation of Scottish golfers.

Jamie’s recent successes include:

  • selection for the Perth & Kinross County (PKC) teams representing the Under 16, Under 18 and Under 21 teams;
  • winning the PKC Under 16 Championship 2017;
  • being selected to play for Scotland in a friendly match against France earlier this summer;
  • coming sixth in the Stephen Gallacher Foundation trophy (U18);
  • finishing second in U16 Nick Faldo Series at Dukes, St Andrews;
  • reaching the Quarter Finals of St Andrews Boys’ Open Championship;
  • he is currently 20th in the Scottish Golf U18 Order of Merit.

Jamie would like to pursue golf in America with a scholarship to an American University where he could obtain a degree whilst playing a lot of golf in the sun!

 

 

 

Jamie Roberts Golf
Jamie Roberts Golf