Loading...

Follow SST Sensing on Feedspot

Continue with Google
Continue with Facebook
or

Valid
Things to Consider When Selecting O2 Oxygen Sensors

This article provides an overview of SST Sensing’s zirconium dioxide O2 oxygen sensor range and interface components; you will find information regarding important features such as housing types, response times, gas temperatures, heater voltages and best suited applications for each product type.

Sensors

There are a number of things to consider when choosing a zirconium dioxide O2 oxygen sensor or electronic interface;

All of SST’s zirconium dioxide sensors have an identical sensing cell, however the housing and specification varies. When choosing your sensor, consider the following:

Cap type; the cap determines the sensor T₁₀₋₉₀ response time. SST offers a choice of two different filters:

  • Full porous cap type which allows gas to enter the sensor from any direction resulting in a fast response time of <4 seconds
  • Porous lid type where only the top (lid) part of the sensing enclosure is porous. The response time of this variant is <15 seconds

Housing style; the housing style you chose will vary depending on your application. SST offer four basic sensor types which will be covered later in this article.

Interface Boards and Instrumentation

SST can supply an interface board which provides the electronics necessary to power and control the zirconium dioxide O2 oxygen sensor range. Alternatively, if you would rather have a complete solution, the Oxygen Measurement System, OXY-Flex or OXY-COMM may better suit your needs. When choosing the option you require, consider the following:

  • O2 measurement range; 0.1 – 25% or 0.1 – 100%
  • Output requirements; digital (RS485 Modbus or RS232) or analogue (4-20mA or 0 – 10Vdc)
  • Location; cable length is important; to maintain the correct sensor heater voltage and minimize noise pickup, SST recommends keeping the cable length between the sensor and interface board as short as possible.
  • Convenience; do you want an “off-the-shelf” solution or configure the equipment yourself?
Application

Consider the application environment in which  your sensor will be working:

Environmental factors; gas mixture, temperature, humidity and pressure levels have a direct bearing on the product you should select; for example, is the gas corrosive; high temperature; high moisture content; do you require barometric pressure compensation?

Mounting; where the sensor and interface board is to be mounted can narrow the selection field:

  • Does the o2 oxygen sensor need to be sealed; is space a restrictive factor; if mounting in a flue, how thick is the wall?
  • Where will the interface board be mounted; do you need a housing; will it be accessible for calibration/maintenance?

Typical applications are listed throughout this article; they are given as examples only; they are NOT the only applications in which the sensors operate.

Sensor Types

There are four basic sensor types within the ZrO2 family; Flange Mounted, Miniature, Probe Type and Screw Fit. The following gives a brief overview of each sensor.

Flange Mounted O2 Oxygen Sensor

Response time: T₁₀₋₉₀ <4 seconds (fast response sensor)

Heater voltage: 4.35Vdc

Gas temperature range: -100°C to +400°C

Mounting style: Flange mounted for easy sealing into a manifold or sampling chamber.

Typical applications: Favoured by SST’s aerospace customers, and those requiring high temperature and high pressure integrity.

Miniature O2 Oxygen Sensor

Response time: 

  • T₁₀₋₉₀ <15 seconds (standard response sensor)
  • T₁₀₋₉₀ <4 seconds (fast response sensor)

Heater voltage:

  • 4V (standard response sensor)
  • 4.35Vdc (fast response sensor)

Gas temperature range: -100°C to +250°C

Mounting style: Can be PCB mounted

Typical applications: Used when measuring ambient gas (i.e. when the complete product is immersed in the atmosphere to be measured).

Response time: 

  • T₁₀₋₉₀ <15 seconds (standard response sensor)
  • T₁₀₋₉₀ <4 seconds (fast response sensor)

Heater voltage: 

  • 4V (standard response sensor)
  • 4.35Vdc (fast response sensor)

Gas temperature range:

  • -100°C to +250°C
  • -100°C to +400°C

Mounting style: Probe comes in three lengths; 80mm, 220mm and 400mm.

Typical applications: Longer probes are ideal for thicker walled flues.

Response time: T₁₀₋₉₀ <4 seconds (fast response sensor)

Heater voltage: 4.35Vdc (4.55Vdc on BM range)

Gas temperature range: -100°C to +250°C

Probe insertion distance: 28mm, 45mm or 55mm (relative to mounting nut).

Mounting style: M18x1.5 thread. Total probe length 75mm.

Typical applications: Boiler furnace efficiency optimisation for coal/oil/gas/biomass; controlled atmosphere monitoring,

The above sensor types are SST’s “off-the-shelf” products. We also offer customisation on all of our products. If your specification is not listed above, please contact us by clicking on the link below and tell us your requirements. Our engineers will be happy to look at your application specifications and advise if we can customise a sensor to meet your requirements.

As mentioned previously in this article, all of our oxygen sensors require interface electronics to operate. You can find details for these products on the following links; OXY-LC Interface Board and O2I-FLEX Interface Board

The post O2 Oxygen Sensor Range from SST Things to Consider When Selecting appeared first on SST Sensing.

Read Full Article
  • Show original
  • .
  • Share
  • .
  • Favorite
  • .
  • Email
  • .
  • Add Tags 
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.

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.

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.

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.

Single Point Level Control

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.

The post Level Switch – Common Applications and What are they used for? appeared first on SST Sensing.

Read Full Article
  • Show original
  • .
  • Share
  • .
  • Favorite
  • .
  • Email
  • .
  • Add Tags 
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
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
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
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-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

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.

The post Types of Interface Boards to Operate Zirconia O2 Sensors appeared first on SST Sensing.

Read Full Article
  • Show original
  • .
  • Share
  • .
  • Favorite
  • .
  • Email
  • .
  • Add Tags 
How to set up and install OXY-LC Interface Electronics with SST's Zirconia O2 Probe?

To operate a zirconia O2 probe, it is necessary to have interface electronics to power and control the sensors. For customers that do not want to purchase the electronics from SST, please read our application note on how to design your own interface electronics.

In this article, we will cover the following;

  • Product overview – what each pin connection is for
  • Installation and initial start-up – step by step procedure on how to install an SST O2 probe with the OXY-LC Interface Electronics
  • Mounting instructions – where is best to mount the O2 probe and interface board in your application
  • what to expect when you connect the O2 probe and interface board
Product Overview

Here is an OXY-LC Interface Board. At the right-hand side of this board you will see 5 pin connections, numbered 1 to 5, these are where the sensor wires will be connected.

At the left-hand side of the board, there are an additional 4 pins, numbered 6 to 9. Pins 6 and 7 are for power supply connections, and pins 8 and 9 are for analogue output connections.

Installation and Initial Start-up

To ensure the best performance the best performance from your O2 probe and interface board, it must be installed correctly. Always handle the interface board using the correct ESD handling precautions.

Step 1 – Install the O2 probe in your application

During installation, to prevent contamination and poisoning the following must be considered;

  • Ensure your hands are clean
  • No silicone-based sealants can be near the sensor probe
  • PTFE tape can be used
  • Use correct O-ring type if applicable

Step 2 – Connect O2 sensor, OXY-LC and host controller or measurement

When connecting the sensor and board, to prevent electrical damage and mechanical damage, the following must be considered;

  • Ensure all power is off
  • Use the correct screwdriver size
  • ESD protection
  • Use the correct mounting screw size
  • Ensure the correct tightening of screw terminals are used
  • Make ground connections first

Step 3 – check installation

It is necessary to complete the following BEFORE switching the system ON for the first time;

  • Ensure compliance with permissible installation position
  • Verify the device is mounted securely and correctly
  • Verify the device and wiring are all undamaged
  • Ensure the cables are strain-free and not twisted
  • Ensure the device is connected properly with all its inputs and outputs complete. All screw terminals are properly tightened.
  • Check all connections for; correct colours/voltages; ensure there is a good mechanical connection and that the supply voltage is correct to prevent any electrical or mechanical damage

Step 4 – Power on

Apply a 24VDC power supply and test the power supply to ensure it is delivering the correct voltage before wiring the device. Failure to do so BEFORE first power on could result in irreversible product damage that is NOT covered by warranty.

When the device is initially powered on, the status of the sensor and board should read the following; communication OK, supply current is normal (<1A) and there is a valid O2% reading after 1 minute.

Step 5 – Test

During test, you should expect to see the following readings from each output;

  • O2% should read between 15 to 25% O2
  • Modbus output should read between 1500 to 2500
  • 0-10V output should read between 6 to10V
  • 4-20mA should read between 13.6 to 20mA

If a fault it detected, an error code is displayed (RS485 variant), or the analogue output will remain at 4mA or 0V.

Mounting

SST recommend housing the interface board in a suitable enclosure to protect from damage.  The interface must be securely fitted to a suitable mounting surface using the mounting holes provided. Protect the interface from accidental shocks or vibrations as this may damage the board.

For more information on how to install and set up SST’s zirconia oxygen sensors and interface boards, please contact click on the contact buttons below to speak to one of our technical support team.

The post How to set up and install OXY-LC Interface Electronics with SST’s Zirconia O2 Probe? appeared first on SST Sensing.

Read Full Article
  • Show original
  • .
  • Share
  • .
  • Favorite
  • .
  • Email
  • .
  • Add Tags 

Strengthening its widely-used Optomax portfolio of accurate, cost-effective and reliable infra-red (IR) liquid level switches, SST Sensing Ltd. now offers the Optomax Industrial series. Industrial Grade Liquid Level Switches that offer the same functionality and operational performance as customers have come to expect from standard Optomax switches, but with the added advantage of greater overall electrical robustness and flexibility. They are capable of accepting supply voltages from 4.5VDC to 15.4VDC or 8VDC to 30VDC and have built-in protection against over-voltage, reverse polarity, and the presence of voltage transients or electrostatic discharge strikes. Delivering an output current of up to 1A, they can be used to directly activate alarm beacons, relays, pumps and motors within the system – so that reactive measures can be taken. A broad variety of electronic output configurations are available, to meet specific application requirements.

The liquid level switches can deal with pressure levels up to 20bar. In addition, industrial operating temperature ranges are supported – standard models covering     -25 to 80°C and extended versions spanning all the way from -40 to 125°C. These devices have compact dimensions, measuring as little as 33.8mm in length, and come in a choice of M12, ½”-20 UNFand 1/4” NPT thread options. They are supplied in two different chemically-resistant, anti-corrosive housing options, with Polysulfone being used for the majority of applications and Trogamid being employed mainly in tasks such as food and beverage processing.

The proprietary Optomax liquid level sensing circuit developed by SST consists of an IR LED and a phototransistor, accompanied by a microcontroller unit. The strength of the IR signal passing between the LED and the phototransistor alters when liquid comes into contact with the sensor tip – thereby providing a rapid and highly precise method to determine the presence of liquid (even in the smallest of quantities) or its or absence. The switches’ output signals can be set ‘high’ in order to correspond either to a wet or a dry state, as is most appropriate for the application and connected circuitry. As this mechanism is based on a solid-state arrangement, with no moving parts involved, it is much more reliable than alternative solutions (such as float switches). Optomax devices are, as a result, not subject to mechanical wear and tear, nor are they susceptible to jamming issues.

About SST Sensing Ltd

For over a decade, SST Sensing Ltd has been developing and manufacturing fluid and gas sensing solutions. These are used to satisfy a broad range of demanding industrial, aviation, medical, transportation and domestic applications. The company’s extensive portfolio of products is made up of optical liquid level sensors, ZrO2 and luminescence based oxygen sensors/analysers, CO2 sensors and CO2 air quality monitors. For more information visit: www.sstsensing.com

Contact SST Sensing Ltd

Siobhan Molloy

Sales & Marketing Manager

5 Hagmill Crescent,

Shawhead Industrial Estate,

Coatbridge, Scotland, ML5 4NS

Tel: +44 (0) 1236 459020

Email: smolloy@sstsensing.com

Follow @SSTSensingLtd

The post Industrial Grade Liquid Level Switches from SST Support Higher Supply Voltages & Temperatures appeared first on SST Sensing.

Read Full Article
  • Show original
  • .
  • Share
  • .
  • Favorite
  • .
  • Email
  • .
  • Add Tags 

Separate tags by commas
To access this feature, please upgrade your account.
Start your free month
Free Preview