CHEMICAL SAVINGS DURING CIP

/0 Comments/in , , /by

CIP-cleaning in the food processing industry

CIP-cleaning facilities are primarily used in those installations wherever supreme necessities are demanded for hygiene and product safety, such as dairies, breweries and in food production. Throughout this process the complete production facility, including tanks and conducts, are purged and rinsed with cleaning agents and water in several cycles.  The aim of Cleaning-in-Place (CIP) is to remove product residues and microorganisms from all wetted surfaces inside tanks, pipework and filling machines while not disassembling the plant. To warrant optimum and economical cleaning, all parts in direct contact with the product must be made according to the principles of hygienic design.  Anderson-Negele’s motto “Hygienic by Design” is an expression of commitment that sensors fulfill this superior demand of the food processing industry in an exemplary manner.

Sequences of a CIP-cleaning within the example of a dairy

The CIP cleaning process takes place in several coordinated process steps. In the first step remains of the product in the installation are extruded and adhering particles removed in the pre-rinsing process. In the next steps, organic traces are eliminated with caustic and mineral deposits by use of acid. Subsequently, the facility is rinsed with fresh water and thus prepared for the next production step.

  1. Pre-rinsing (water)
  2. Cleaning (caustic)
  3. Mid-cycle rinse (water)
  4. Cleaning (acid)
  5. Rinsing (freshwater)

 

Optimization of the CIP Process

A CIP cleaning process in commonplace applications lasts between 60 and 90 minutes. The operator of a production facility consequently suffers from downtime in production capacity leading to a loss of products, and from increased cost for the consumption of water, energy and chemicals.

The hygienic design of the complete production facility and automatized processes are key factors for a reduction of the cleaning cycle times and for an increase in the efficiency and productivity of the process itself. Being an experienced specialist for sensor technology in hygienic environments, the sensors and process connections from Anderson-Negele are perfectly adapted to the requirements of the food industry and ensure the safe and economical cleaning of the facility and installations.

Why Morton Controls together with Anderson-Negele’s ILM-4 could help you

 The analysis of the return media is one of the most important steps for an environmentally friendly and cost-efficient process. The ILM-4 inductive conductivity meter plays a central role in precisely determining the phase separation: during the discharge of the liquids at each cleaning stage the media are differentiated with cost-saving accuracy.  Re-usable cleaning agent that flows off after cleaning can thus be returned to the tank to the maximum possible degree. In a separate, internal circulation and for permanent optimum cleaning result, its concentration is adapted to the specified ideal value by re-dosing with detergent and fresh water in the cleaning agent tank. The ILM-4 conductivity meter also ensures the highly precise measurement of conductivity and temperature required here.

Inductive Conductivity Meter ILM-4

The ILM-4 is designed for hygienic applications in food-, beverage- and pharmaceutical industries and controlling of CIP processes (e. g. phase separation detergents/water). The ILM-4 is currently equipped with the IO-Link in parallel.  IO-Link offers important benefits over analog technology when it comes to reliably controlling the entire process technology with a variety of measuring points, control and operating elements.

FEATURES/ADVANTAGES

  • CIP/SIP cleaning up to 150 °C/maximum 60 minutes
  • Wear-free, inductive measurement
  • In contrast to conductive measurement procedures, no problems with electrode deterioration or polarization.
  • Accurate measurement through compensation of temperature influences.
  • High reproducibility of ≤ 1 % of the measurement value.
  • Analog outputs for conductivity and temperature are a standard feature.

    Anderson-Negele’s ILM-4 with IO-Link

  • Analog outputs for conductivity, temperature or concentration are freely adjustable.
  • Rapid temperature response time T90 15…60 s
  • Installation in tube diameters from DN 40

 

For more information please contact the Morton Controls team:  0861 000 393, sales@mortoncontrols.co.za, www.mortoncontrols.co.za

 

Anderson-Negele’s NCS-M Capacitive Level Sensor with the MPI-300 programming adapter

/0 Comments/in , , /by

 

In combination with theMPI-300 USB programming adapter, the NCS-M sensor can be individually adapted to the application used by the customer. In addition to setting the device to the appropriate medium, switching threshold, hysteresis and time delay can also be individually configured.

 

Application examples of the capacitive level sensor:

  • Limit detection in vessels or pipes
  • Product monitoring in pipes
  • Pump/dry running protection
  • Detection of syrup and fruit concentrate

 

 

 

 MPI-300 USB programming adapter in combination with the NCS-M sensor

  1. NCS-M-12:
  • Version with enhanced measurement range for critical media (e.g. Oil, Fat)
  • No adjustment necessary
  • The switching threshold, hysteresis and time delay parameters can be set for the sensor for complex applications
  • Insensitive to foam and adherence
  • Very short response time (< 100 ms)
  • IP 69K

2. The MPI-300:

Adapter for the universal programming of the NCS-M capacitive level sensor family. Level detection even for media with a low or no water content such as syrup, fruit concentrate, alcohols and oils with a dielectric constant εr (Dk) ≥ 2.

The switching threshold, hysteresis and time delay parameters can be set for the sensor.

How to get the most from your Feed Plant

/0 Comments/in , , /by

How to get the most from your Feed Plant

UWT in partnership with Morton Controls have the solutions for the Animal Feed Industry

The process and storage environments within the feed industry sector often have factors such as moisture, vapor and fat to consider which cause the materials to have caking tendencies.  In order to withstand and remain fully operational, UWT devices have special coatings which in turn provides the customer with economically viable solutions.  With years of experience within the feed industry and the continual research and development of measurement technology, UWT sensors offer wide and innovative versatility.

Reliable measurement technology for versatile solutions within the animal feed industry

The production of high-quality animal feed and pet food is an important economic growth sector. As well as livestock feed, this sector also includes pet and sports animal nutrition.

The requirements of animals in terms of nutrition are diverse and so a variety of mixed feed formulations is manufactured. Accordingly, the focus of the measuring technology equipment in the manufacturing plant is on the ability to easily and quickly adapt to the varying processing conditions. The formulation of a compound feed is based on the particular use for which the product is intended. Similarly, the use of appropriate measuring sensors is in accordance with the relevant requirements of the application.

The level sensor is an indispensable element of the technical equipment within a modern feed production plant for the detection and monitoring of levels and limit levels within the different process stages. All UWT devices are designed to allow easy integration into the various processes and are characterized by being completely maintenance free in accordance with the principle of “install and forget “.

  1. UWT Portfolio

UWT provides sensors for the measurement of level and limit level in bulk solids and liquids. Depending on the medium and application, different measurement techniques are used as well as a range of complete systems for level monitoring and visualization. The product lines include not only an economic standard but also particularly high grade, premium versions. UWT devices are completely maintenance-free and, importantly, carry international certificates.  All limit switches are available with universal voltage electronics as standard or as an option.

1.1 Sensors for Level Detection:

Rotary Paddle Level Switch – Rotonivo® Series 3/6

  • Variable extension lengths – either rope or tube
  • Extension and process connection available in stainless steel
  • Adjustable sensitivity
  • EHEDG compliant
  • Suitable for use in high temperatures of up to 1,100°C
  • Modular design
  • Rotonivo® 6000 SIL 2 compliant
  • All-rounder suitable for all applications
  • Wide variety of configuration options

Rotary Paddle Level Switch – Rotonivo® Series 4000

  • Variable extension lengths – either with pendulum shaft or rope extension
  • Version with plastic housing and process connection
  • Various process connections
  • Adjustable sensitivity
  • Modular design
  • The plastic design offers increased corrosion resistance

Vibrating Fork Level Switch – Vibranivo® Series 1/2/5/6

  • Variable extension lengths – either rope or cable extension
  • Extension and process connection available in stainless steel
  • Sensitive to the lightest bulk materials (< 5g/l)
  • EHEDG compliant
  • Version with separate housing available
  • NAMUR-electronics
  • Suitable for interface measurement within sediment tanks/containers

Vibrating Fork Level Switch – Vibranivo® Series 4000

  • Variable extension lengths – either rope or cable extension
  • Extension and process connection available in stainless steel
  • Extension, process connection, and oscillators cast from one mold
  • Sensitivity from 30g/l

 

Vibrating Single Rod Level Switch – Mononivo® Series 4000

  • Variable extension lengths – either rope or cable extension
  • Heavy mechanical loading
  • High-quality material in the process (SS 316L)
  • High surface quality
  • Sensitivity adjustable in 4 settings
  • Temperature range from -40°C to +150°C
  • Robust version
  • Suitable for overpressure up to 16bar
  • Compact Limit switch with threads from 1″

Capacitive Level Switch – RFnivo® Series 3000

  • Variable extension lengths – either rope or cable extension
  • Extension and process connection available in stainless steel (Stainless steel probe material with FDA conformity)

  • Version with plastic coated extension available
  • Can be used in low dielectric values from 1.5 DK
  • EHEDG compliant
  • Suitable for use in high temperatures of up to 500°C
  • Suitable for use in process pressures of up to 25bar
  • “Active Shield Technology” for anti-caking functionality
  • Available as remote version
  • User-friendly parameter setting via display and function buttons with measurement results given also via display
  • Simple automatic calibration at startup

Capacitive Level Switch – Capanivo® Series 4000

  • Variable extension lengths – either rope or cable extension
  • The version available with plastic housing, process connection, and extension
  • Extension FDA compliant
  • Can be used in low dielectric values from 1.6 DK
  • Suitable for use in high temperatures of up to 180°C
  • “Active Shield Technology” for anti-caking functionality
  • Integrated earthing in-process connection
  • No calibration required

1.2 Sensors for Level Control:

Electro-mechanical Plumb Bob Sensors – Nivobob® Series 3000

  • Measuring range up to 50m (silo height)
  • Easy commissioning
  • Rope and tape version
  • Integrated tape cleaner
  • Threaded or flanged process connection
  • Modbus and Profibus interface
  • Reliable measurement results independent of material
  • Suitable for interface measurement within sediment tanks/Containers

Electro-mechanical Plumb Bob Sensors – Nivobob® Series 4000

  • Measuring range up to 30m (silo height)
  • Easy commissioning
  • Rope and tape version
  • Integrated tape cleaner
  • Threaded or flanged process connection
  • Aiming flange for angled installation

Radar sensor – NivoRadar® 3000

  • Measuring range up to 100m (silo height)
  • Aiming flange model
  • Robust stainless-steel housing IP68
  • High sensitivity (DK ≥ 1.6)
  • Temperature solution up to +200°C
  • 78 GHz technology
  • 4° beam angle
  • Lens antenna and mounting flange are flush
  • Integrated lens cleaner
  • Simple, six-step commissioning

Visualization – Nivotec® Series 2/3/4

  • Web-based visualization solution
  • Level monitoring and analysis via ethernet
  • Remote access via internet option
  • Complete system for plug and play
  • Sensor interface for 4-20mA or Modbus RTU
  • Expandable to monitor up to 15 or 30 silos within a plant
  • Full, empty, demand, fault alarm via email option
  • Signal output for silo full alarm
  • Effective silo management

Complete system for:

  • Level indication
  • Trend display
  • Data storage
  • Remote fill level analysis

The main processes involved in the production of feed are storage, weighing and mixing with conditioning, pelletizing, followed by cooling and crushing. There are also other processes such as extrusion, conveying and dosing applications. UWT level technology is used in almost all sectors, for level indication or to control limit levels for all bulk solids.

 

Anderson Negele’s ILM-4 conductivity sensor with IO-Link

/0 Comments/in , , /by

Conductivity sensor with IO-Link

The ILM-4 conductivity sensor with IO-Link is a big step to industry 4.0 in hygienic process technology.

Proven industry standard now also for hygienic and aseptic applications

IO-Link offers advantages in process control and monitoring. The ILM-4 conductivity sensor, the first of a whole range of measuring instruments to be equipped with an additional IO-Link interface, is a well-known and proven conductivity sensor on the market. This will be followed in due course by the sensors ITM-51 for turbidity, NSL-F for level, L3 for pressure and D3 for differential pressure and volume, all based on the modular platform with fail-safe plug-and-play technology with standard cable for time-and-cost-saving installation and set-up.

The (R)evolution of conductivity measurement

IO-Link offers significant advantages over analogue technology when it comes to reliably controlling the entire process technology with many measuring points, control and operating elements. Set-up and installation are easy and cost-effective. A three-pole standard cable is sufficient for the signal transmission and power supply itself. In practice, point-to-point connections are made at field level from various sensors to collection points, so-called IO-Link masters, and from there via Fieldbus system to the control centre.

 

Simple data transfer becomes intelligent communication

With IO-Link, data streams in the opposite direction towards the sensors are now also possible. In this way, the status of the sensor can be checked and specifically queried at any time. This makes it possible to detect potential faults, signs of wear or an increased risk of failure at an early stage and helps to avoid production downtimes.

“Plug-and-play” takes on a whole new meaning

Sensor replacement of the ILM-4 with IO-Link becomes easier and safer than ever before and can be carried out independently, at any time and by any employee without any programming effort. The device configuration of each connected sensor can be stored in the IO-Link Master. Immediately when plugged in, the new sensor is automatically recognized, configured and parameterized by the IO-Link Master.

The new dimension in hygienic measuring technology is digital and analogue, compact or remote. It is: modular

ILM-4 conductivity transmitter with IO-Link creates planning security and flexibility for status control and sensor diagnostics for preventative maintenance avoids production downtime.  The combination with the modular platform, with the separation of sensor and electronic unit in the optional remote version, creates a unique constellation of hardware and software that is unparalleled in flexibility, simplicity and system compatibility.

PETROCHEMISTRY: CHLORINE-ALKALI ELECTROLYSIS

/0 Comments/in , /by

PETROCHEMISTRY 

 CHLORINE-ALKALI ELECTROLYSIS

The chlorine-alkali electrolysis is an important procedure in the chemical industry. The products chlorine, hydrogen, hydrochloric acid and caustic soda are generated from sodium chloride. There are three manufacturing methods: the diaphragm, the membrane and the amalgam process.

The LiquiSonic® analyzer provides an advantageous utilization in the varied process steps of the three methods. Foremost, the customer gains the advantages of a reduction in raw material and energy consumption, as well as an increase in the yield.

 

LiquiSonic® measuring points in the processes of the diaphragm method of the chlorine-alkali electrolysis

 

Preparation of end products

1.1  Caustic soda concentration

The market ready caustic soda (NaOH) typically has a concentration between 45 wt% and 50 wt%. Since NaOH gained from electrolyzer cells only yields a concentration range between 12 wt% and 33 wt%, it is concentrated in cascade evaporators.

If together with NaOH the solution contains NaCl (diaphragm method), the excess salt in the caustic soda precipitates in a crystal form during the evaporation. This way, the NaOH-concentration is elevated to 45 wt% and 50 wt%.

The LiquiSonic® analyzer continuously determines the concentration of caustic soda at any time after evaporation. A subsequent dilution of the caustic soda to a customer specific product concentration, can also be monitored.

ADVANTAGES:

  • Continuous concentration monitoring of the caustic soda
  • Reduction in the energy costs during the evaporation process

1.2 Chlorine gas drying

Water content needs to be removed from the chlorine gas before it is further processed as its corrosives elevate at a moisture content of over 30 ppm. For the drying, the chlorine gas is routed into the absorption towers, where the water content in the chlorine gas is absorbed with highly concentrated sulfuric acid (80 – 99 wt% H2SO4).

The effectiveness of this drying process significantly influences the productivity and quality of the gas. Therefore, a reliable measurement of the H2SO4 concentration is vital. The LiquiSonic® analyzer offers a continuous and safe monitoring of the H2SO4-concentration, in opposition to conductivity and density measurement.

ADVANTAGES:

  • Elimination of labour intensive sampling
  • Continuous monitoring of H2SO4-concentration
  • Clear concentration determination signal between 80 wt% and 100 wt% H2SO4
  • Ensuring the desired Cl2 dryness to avoid corrosion in the system

1.3  Hydrochloric acid production

The chlorine gas that is generated on the anode of the electrolyzer with the added hydrogen form the base materials for the synthesis of hydrochloric acid. Both gases are fed into a burner and react to form hydrogen chloride. Subsequently, the formed HCI-gas streams from the burning chamber into the integrated isothermic falling-film-absorber. Here, the gas is absorbed with the help of water or diluted acid, whereby concentrated hydrochloric acid (37 wt% HCI) is formed.

Using the LiquiSonic® analyzer, a continuous monitoring of the hydrochloric acid concentration is possible. This allows for deviations to be recognized from the target concentration and to react accordingly.

ADVANTAGES:

  • Continuous concentration monitoring of hydrochloric acid (20-40 wt% HCl)
  • Ensuring an extremely precise target concentration

Advantage of sonic velocity as compared to conductivity and density

 

 

Efficient silo management for smooth process flow

/0 Comments/in , /by

Efficient silo management for smooth process flow

The electromechanical Lot system Nivobob® 4000 is equipped with a Modbus function which allows easy connection to visualization systems, thus providing an economic silo management solution.

 

Multifunctional unit for discontinuous level monitoring in bulk goods

 

The electromechanical measurement device is an invaluable instrument in the field of inventory management due to its advanced electronics technology. The reliable electromechanical lot system Nivobob® with its robust mechanical design has for that reason become the choice of many plant operators across the globe faced with demanding conditions. The Nivobob® series of plumb bob sensors is used for continuous level measurement within bulk storage silos and for interface measurement. The simple electromechanical measurement principle is a truly reliable all-rounder in most bulk materials.

 

Nivobob® 4000 with Modbus function

The electromechanical Lot system Nivobob® 4000 is equipped with a Modbus function which allows easy connection to visualization systems, providing an economical silo management solution.

UWT GmbH has developed an economical and practical solution in terms of centralized content level monitoring; especially suited for the storage processes within industrial plants. The maintenance-free electromechanical lot system Nivobob® is mounted on each silo within the plant for continuous level monitoring. The plumb bob systems of the economical Nivobob® 4000 series come standard with a Modbus interface which allows for quick and easy connection of the units to the visualization system.

Parameters such as content level, operating time, pending replacement intervals, sensor status are available to the operator. For level control, diagnostics etc. the license-free visualization software Nivotec® is used: The information is sent from the electromechanical lot sensors to the visualization system via Modbus. The operator can access the required information from any PC 24h a day. The software with its data storage and trend analysis function enables the operator to perfectly plan material disposition and any logistics required. The outcome is efficient silo management resulting in cost saving due to planning security. With this new development UWT has responded to the demands for an affordable solution which combines reliable level monitoring with live-data visualization for effective silo management.

 ADVANTAGES:

  • Communication between Nivotec® visualization software and Nivobob® 4000 lot systems can be    conveniently controlled directly from your PC
  • Modbus RTU interface reduces the installation time by using Daisy-Chain-Wiring
  • Silo full detector can be wired directly to the Modbus RTU interface of the Nivobob® 4000

For more information on UWT products contact Morton Controls today.

The Mining Industry is Booming!

/0 Comments/in /by

If you are not using quality components in the mining industry, then you are going to miss out.

Quadbeam’s sensors are top drawer and here is why:

Quadbeam Technologies Sensors are products that can be relied on, due to its accurate, rugged construction, and repeatable signal.

It’s excellent performance means you have control of Suspended Solids and Turbidity in the Mining Processes.

What are the S Series bodies manufactured from?

Polypropylene or PVDF are the main ingredients, and they give excellent chemical resistance for challenging chemical environments, often found in mining applications.

Their Application usage for the mining industry is broad-

  • Raw Water intake monitoring
  • Water Treatment processes
  • Control of flocculate dosing
  • Clarifier overflow monitoring
  • Filter breakthrough monitoring
  • Tank Profile monitoring

The Key Benefits are-

  • Provides excellent chemical resistance
  • Repeatable, reliable and accurate signal
  • Long lasting

The Products to look out for are:

The S10-IMM, S20-IMM and T30-IMM

Quadbeam S20-IMM

We have a nice story from the mining industry for you.  Quadbeam, based in New Zealand, had a client, situated in one of the largest rock quarries, who had a problem in their sand and aggregate washing plant.  The problem was with the recycled waste water.

Following a very painful manual process, and umpteenth errors, where the waste water was being fed back to the sand washing plant, they had a Quadbeam S20 suspended solids sensor installed in a vertical section of the  pipe.  This measured, on a continuous basis, the suspended solids in the recycled water.

 

 

Quadbeam S10-IMMThe flow and suspended solids measurements were sent to a PLC, where it calculated the mass flow of the solids and adjusted the dosing pump so that the correct level of chemical addition was achieved.

 

After the flocculation process, the solids settle out in 3 large cone clarifiers.  Then, the clean recycled water is sent back to the plant.

For the last 2 years, the plant has produced consistently clear recycled water, with minimal maintenance involved.

Should this be a situation you wish to rectify, please contact us for more info on Quadbeam’s sensors.

Quadbeam T30-IMM

TELEPHONE: 0861 000 393

EMAIL:  sales@mortoncontrols.co.za / ian@mortcon.co.za

cip system

The CIP System – Within the F&B Industry

/0 Comments/in /by

In food manufacturing, cleaning-in-place or the CIP system is a standard component for ensuring reliable and efficient adherence to quality standards. The requirements placed on sensors, used for process control, are particularly high in the food and beverage industry.  They are tailored solutions for optimizing the CIP process, using turbidity and conductivity sensors.

What is involved?

The CIP system consists of numerous interlinked steps. Plant operators need to take into account more than just the downtime of the system. Costs also arise from the consumption of water, chemicals and energy, as well as product loss.

The sequence of the individual cleaning cycles is often still time-controlled. These fixed cleaning intervals will guarantee that the system is always cleaned properly.  However, more water, and cleaning solution and time, may be consumed than would actually be necessary for the medium being processed.

What is the solution?

The solution is to automate control of the CIP system using turbidity and conductivity sensors. The average water consumption, depending on the product, is 1.5 to 3 liters per processed liter of product.  Half of this water is used for cleaning the system.

Are there disadvantages?

A disadvantage of cleaning processes with fixed time intervals is that the maximum required cleaning duration must be used for each cleaning cycle. For example, the removal time for pasty media is considerably longer than for less viscous products. Therefore, when performing CIP cleaning after producing media with less viscosity, more water is used than is necessary.

This, however, can be remedied through automated process control using the turbidity and conductivity sensors. Water consumption at large F&B manufacturing plants can be lowered from an average of 6,500 to 2,500 liters per cleaning cycle simply by deploying an intelligent phase detection system. This will result in savings of water and wastewater costs.

In addition, shorter cleaning cycles lead to a lower consumption of acids and bases.  The use of chemicals can be precisely controlled by measuring their concentrations using the conductivity sensor, allowing their consumption to be further optimized.

What are the production-related stats?

Experience has shown that production-related losses reach 0.5% in large operations and 2.5% in small operations. It is particularly the plants with low levels of automation that experience significant losses in product.

The precise and rapid detection of water-to-product phases using the turbidity sensor lead to reductions in product losses of 5–10% in customer field projects. A CIP system usually takes 60–90 minutes. A hygienic design of the entire system is therefore an important contributor to shortening the cleaning cycles and increasing the efficiency and productivity of the process.

How can Morton Controls help?

As a specialist for sensor systems in hygienic processes, we, at Morton Controls, have sensors and process connections that are optimally designed for the demanding requirements of the F&B industry and that ensure reliable and efficient cleaning of the system.

 

 

 

 


 

History Around Coal Mining

/0 Comments/in /by

We love a little bit of history, and coal mining has an interesting tale to be told.

One of the largest mining industries, mining for coal started out in the 18th century and boomed all the way to the 1950’s.  Although maybe not as huge as some other mined commodities, coal is still a valuable form of energy for open-pit extraction.

Interestingly, tunnelling into the earth to pull the coal was the initial method, but had to be stopped due to the perilous vapours that were emitted (carbon monoxide, carbon dioxide, and hydrogen sulphite) deadly to say the least.

The sensors now used in the coal mining process have helped with detecting these harmful vapours and have progressed from the mining’s canary method.

What is the Miners Canary?

If you know mining, you would have heard of this amazing story.  Very simply, miners would take a canary in a cage down with them as they descended. Canaries were known to be very sensitive to odourless vapours, such as carbon monoxide, and they would show effects of distress, rocking from side to side, before falling off their perches.

While not a very animal safe procedure, it was known to have saved many human lives.  After a time, the canary method of detection was stopped as it proved not to be as effective as they assumed it was.

In steps the Pellistor

The Pellistor was introduced as a catalytic sensor and was able to detect a very wide range of toxic vapours and flammable gases.

Due to limitations, such as malfunction when exposed to chemicals with chlorine, sulphur, halogen, and any metals containing silicon or lead; as well as high costs to maintain the pellistor, this method was withdrawn.

Infrared LED-based Gas Sensor

The more modern and more effective method is the infrared LED – based Gas Sensor.

The advantages of this method are:

  • A wider measurement range
  • A rapid response rate
  • Background gases do not affect the gas sensor, as it did with the Pellistor
  • Each gas can be detected and measured separately