Friday, 1 November 2013

Measurements of Dustiness - 'Hairy Arm' Test .... and Improvements !

Dust in bulk materials can have several and varied impacts on users and producers.

Impacts on the producer include:
  • Cost of wasted material.
  • Process time and equipment optimisation.
  • H&S related processing issues.
Cost to the user include:
  • Materials purchased that can be utilised.
  • Processing difficulties.
  • H&S related issues in handling.
So how exactly do you measure the dustiness of a bulk material ? 

I've seen methods used, for example with desiccant materials, where a QC operative assessment is to plunge an arm into the bulk container, remove it from the bulk and assess the amount of dust caught on the hairs of the arm ...... the 'Hairy Arm' test.

At FIL, we now offer an instrument DustView II which uses a 'drop test' for the bulk being investigated.  Originally developed in conjunction with a major manufacturer of fertilisers, a measured weight of material is placed in a small hopper and a valve opened rapidly to allow the material to drop down a tube, under gravity, impacting on a baseplate mounted inside a chamber below.  This chamber is monitored by an optics based dust monitoring system which fives an output based on obscuration / scattering of a light beam.  The level of scattering is dependent on the dust concentration released during the fall and impact of the process.

Other methods exist and although it is difficult to correlate different systems or link any measured values to explosability limits etc., as an indicator of dust levels and a quality control tool it has proved to be a quick and useful instrument for both manufacturers and users.

Wednesday, 14 December 2011

EU Decides - Nano Material Definition (measured by number concentration rather than mass)

On 18 October 2011 the EU Commission adopted the Recommendation on the definition of a nanomaterial. According to this recommendation a "Nanomaterial" means:
A natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm - 100 nm.
In specific cases and where warranted by concerns for the environment, health, safety or competitiveness the number size distribution threshold of 50 % may be replaced by a threshold between 1 and 50 %.
By derogation from the above, fullerenes, graphene flakes and single wall carbon nanotubes with one or more external dimensions below 1 nm should be considered as nanomaterials.
Europe is the first area to make a decision on this definition and guidance from the Scientific Committee (SCHENIR) included an argument, that in its opinion "a low mass concentration of nanoparticles in a product may still represent a high number of particles and a mass based distribution can be skewed by the presence of relatively few large and thus heavy particles". Therefore it considered number size distribution as a more relevant metric for possible effects of nanoparticles than mass concentration.

This is a move away from other existing regulatory / industry specific metrics, which are based on mass and aerodynamic separation and sampling methods and it will be interesting to see how this decision impacts on these other measurement systems in the future.  The dosage metric for inhaled delivery of drug products is one area which comes to mind, breathing / medical air definitions together with ambient environment and vehicle exhaust monitoring.

It is still very early days in 'nano material' safety.  We continue to investigate the impact of micron sized particles on environmental health and there will be some years of discussion and development of standards and methods.  I'm sure that discussion will follow on how we define the size measurement, based on method used, but whatever the method I suspect that it has got to be easier to measure dimensions rather than trying to capture particles in a specific size range < 100nm and then weigh them (and by the way this could be debated with micron sized particles too) ?

Tuesday, 18 October 2011

The Filtration Society - a source of Knowledge and Support

The Filtration Society is a not for profit organisation formed by filtration / separation professionals back in 1964, with an aim to advance and disseminate knowledge on the design and use of filtration and separation techniques in industry, commerce and other walks of life.

The Society has a membership covering over 30 countries and continues to offer training events, conferences and exhibitions for individuals in filtration and separation technology, both for those new to the subject and for the experienced.

The Society is always open to new members; students, individuals and corporates, so have a look at the website and see what may be of interest and benefit to you.

Thursday, 1 September 2011

Simultaneous UK Aerosol Conferences

It's all happening in the first full week in September which brings two conferences / exhibitions for particle scientists in the UK.

EAC 2011 the European Aerosol Conference from 4th - 9th Sept in Manchester this year promises to be the biggest and best yet, with a packed schedule and a good number of exhibition stands.  FIL will be joining the Palas GmbH team for another exhibition and will again be showing a number of innovative particle sizing instruments including:
  • Fidas Mobile - from the FIDAS range for air quality monitoring
  • Promo - Aerosol Size Spectrometer
  • Charme and UF-CPC - electrometer and universal fluid condentation particle counter from the Nano range
  • DNP 3000 - carbon / metals spark particle generator
    Fidas Mobile
PSA 2011 Particulate Systems Analysis from 5th - 7th Sept in Edinburgh, unfortunately also during the same week.  This conference again look to be well attended and I'm also looking forward to visiting Edinburgh, but this time only on the Tuesday as a visitor . 
There may be a Welas digital 3000 Aerosol Size Spectrometer system on display at the  Particle Technologies booth (an independent testing company), for those who are interested in Palas equipment.

Sven Schutz and Jurgen Spielvogel will also be presenting a couple of papers at each of the conferences.

Looking forward to a busy week and to meeting many new contacts involved in all aspects of aerosol science. See you in Manchester and Edinburgh.

Thursday, 26 May 2011

Cambridge Particles Meeting - a quick review

I attended the Cambridge Particles meeting for the first time, held in the Engineering Department of Cambridge University on Friday 13th May 2011.  I didn't know what to expect, but the meeting had a friendly academic atmosphere, with scientists and technicians present having a range of interests in aerosol science, although as exhibited by the presentation titles, vehicle emissions were the significant focus.  In addition it is worth mentioning that the meeting was free to attend, one of the very few that I'm aware of at this quality.

The presentations given at the meeting are listed below, together with my brief personal overview.  Proceedings will be available at a later date if you visit the Cambridge Particle Meeting web page, to see what they were really about!

Adam Boies - University of Cambridge / University of Minnesota - Gas-Phase Production of Core-Shell Nanoparticles by Decoupled Processes

The design and generation of nano-particles for use in medical applications as precise targets for the adsorption of radiated energy e.g. MR, Laser, IR, UV in treatments of disease. Also identified to have some potential for use in other applications such as film coatings to provide catalysis required for fuel cells. 

Simon Payne - University of Cambridge / Johnson Matthey - Visualisation and Monitoring of Diesel Particulate Deposition

Reviewed the blockage process of pores in Diesel Particulate filters using an electron microscope to monitor individually identified pores over the blockage cycle.  Some fantastic images to show diesel particulate forming almost a fibrous plug across ~10um pores and then related to witnessed differential pressures.

Phil Price - Ford - Study of Particle Number Emissions from a Turbo GDI Engine using Fast Response

Euro VI emissions legislation applying to new cars will be coming into force from 2014, and whilst PM emissions with gasoline powered vehicles are not as high as seen with diesel engines, most of which currently require exhaust particulate filtration to reduce PM levels to the ever tightening regulated limits, new targets are still a challengeThis presentation gave an interesting review of some work at Ford to identify the modes of particulate formation during the standard driving cycle, highlighting the complex engine management and control systems of today that look after the system optimising all parameters.  I still remember the happy days of carburettors and simple flow balancing where performance adjustment came via a screwdriver !!

Alex Charlton - University of Leeds - Particle Characteristics and their Influence on DNA Damage Induced by Exhaust PM Collected from a HD Diesel Engine Using Biofuels

Biofuels - 'greener' fuel, but is there a toxicity impact of their soot?  Results of DNA damage assays were presented which appeared to show DNA damage correlation with PAH concs.

Paul Quincey - National Physical Laboratory - Particle Measurement for Ambient Air Regulation: Current and Future Techniques

Paul provided an update for the group on the current developments coming out of ISO TC24  and CEN TC264 working groups including identified work ongoing with WG32 - Air quality - Determination of the particle number concentration and ISO TC24 WG12 development work for ISO/NP 27891 Aerosol particle number concentration -- Calibration of condensation particle number counters.

Andrew Smallbone - cmcl innovations / University of Cambridge - Evolution of Particle Size Distribution within the Engine Exhaust and Aftertreatment System

Andrew presented recently modeled data for particle formation from a combustion process, though identifying that experimental verification was yet to be performed.

Roger Watson - University of Cambridge - An Improved Metric for the Sooting Propensity of Fuels

Roger introduced a new measurement metric to improve on the empirical technique whereby a fuel’s smoke point is identified as the maximum height of its laminar flame burning in air at which soot is not released from the flame tip, which has been used for many years as a measure of fuel sooting potential.

Mike Braisher - Jaguar-Land Rover / University of Oxford - A Statistical Method for Particle Number Emissions Measurement Variance Analysis

Mike introduced an approach to improve measurement variance through the use of two separate measurement instruments on the same measurement ...... music to an instrument seller's ears !

John May / C├ęcile Favre - Association for Emissions Control by Catalyst - Particle Emissions of Powered 2-Wheelers

John provided an entertaining review of testing carried out by AECC for its membership, on a range of two wheeled vehicles (typically scooters / mopeds / bikes etc. but refer to legislator's definition) which are about to be covered by legislation for emissions.  This work was commissioned to identify how close existing products were to the requirements and what action may be necessary to comply. 

Phil Whitefield / Prem Lobo - Missouri University of Science & Technology - Preliminary Results on PM Emissions from APUs and Tire Smoke Generated by In-Service Commercial Transports

Phil and Prem reported on their project, funded by the Airport Cooperative Research Program
(ACRP 02-17), to measure Aircraft PM emissions from AFU's and tyres / brakes.  The methodology was reported, but with monitoring still ongoing, data was not yet available for release.

Huayong Zhao - University of Oxford - Measurement of Temperature, Soot Volume Fraction and Particle Size in a Santoro Burner

A new methodology was presented combining Cone Beam Tomography and Three Colour Spectrometry to measure a range of parameters for soot from in a Santoro Burner flame.

David Kittelson - University of Minnesota - Issues Associated with Solid Particle Measurements

David reviewed test data produced using a very wide range of TSI particle measurement equipment examining the impact of the 23nm lower size cut off defined by the PMP and the influence of volatiles and the method of removal.

I'd like to add my thanks to Simon Payne for his organisation, together with Cambridge University Engineering Department and the sponsors, Cambustion Ltd., for the welcome and the catering.

I'd recommend the Cambridge Particle Meeting to anyone with an interest in particle science and look forward to next year's meeting.

Wednesday, 20 April 2011

Aerosols In the Environment Meeting at the IOP

Just got back from attending the Aerosols in the Environment technical meeting at the Institute of Physics in London.

This was a joint meeting with the IOP Environmental Group and the Aerosol Society and was well attended by 35 people from a range of academia, meteorological groups and aerosol characterisation instrument suppliers.

As some reading this may know, my background is in high efficiency filtration and so I'm quite new to this area of environmental aerosol science.  However, having originally joined the Aerosol Society back in the 1980's and only rejoined last year, it was interesting to see such a level of activity still on-going, listen to the developments made over that time and meet up with people involved.  I enjoyed and learned from all the presentations given and I add a personal impression from the presentations given at the meeting below. (I hope that the full presentations will be made available at either the IOP / Aerosol Society)

Prof Ian Ford - Current understanding of aerosol nucleation in the environment
I suppose that I always considered particles to be formed from breakdown activity i.e. particles are formed from the breakdown of some sort of bulk.  I'm familiar with a simple condensation process where a particle passing through a saturated vapour initiates a growth by condensation. This is the principle used in CPC's to grow small particles to a size large enough to be counted using optical systems, but I confess that the subject of nucleation, describing the formation of particles from molecular agglomeration hadn't really occurred to me, so a whole new vista was opened at this meeting.

Prof Ian Colbeck - Indoor Aerosols
Indoor Aerosols are an area of interest for a filtration specialist and instrument supplier, as much of our work is involved with HEPA / ULPA filtration systems used in HVAC installations and more recently I've been involved in vacuum cleaner assessments.  It was interesting to see a 'tricked up' house being monitored with every instrument you can think of to identify sources of indoor aerosol and other contaminants.  I have to admit to being rather unsurprised that cooking and walking across carpets re-suspending dusts was found to be some of the highest source of particulates in the homes monitored.  However, following this talk I now have evidence that this is a significant source of re-suspended aerosols in homes in the developed world and a significant reason for not vacuuming!!
Additional monitoring results were offered from Pakistan, but here again the rather unsurprising result was that cooking with open wood burning stoves in a closed area and heavy smoking at social events without ventilation were the major causes of extremely high respirable particulate levels. The location of animals close to the cooking and food prep areas also gave high biological loadings in the aerosols.  I suppose with these type of issues you still need to measure the parameters to prove and quantify levels.  The values measured are certainly huge in comparison to those tolerated in the developed world.

Dr Claire Ryder - Using aircraft measurements to determine the radiative effect of Saharan Mineral Dust
Did you know that dusts blown up from the Sahara travel across the Atlantic to North and South America and did you know that the level of dust in the atmosphere contributes to global cooling?  Having already been covered by Prof Ford in his presentation described as some form of 'active intervention', I now have a mental picture of atmosphere modifier stations seen in some sci-fi movies; huge chimneys sucking up desert dusts and pumping particles high into the atmosphere to cool the earth down!
Anyway, to see the data and pictures of the dust plumes being tracked and the impact measured by researchers flying in a BEe-146 aircraft through these, taking samples and making measurements was again an eye opener for me.  The global scale of influence of desert sourced dusts was a bit of a surprise and the influence of the material type in terms of adsorption of incoming radiation was again a learning experience for me.  Brave people these researchers, deliberately flying into hazardous environments for aircraft!

Prof Colin O'Dowd - Biogenic influences on marine primary and secondary particle formation - recent advances
Once again, I hadn't really thought too much about the major sources of aerosols and the influence of the oceans.  Many of our client's filter development focus, particularly for turbine protection, has been related to protection of equipment on offshore installations and most of the particulate dealt with, at least that I was aware of was sea salt.  The impact of the aerosol generation from the oceans turns out to be highly significant, with phytoplankton blooms in the oceans contributing seasonally to this impact.
Fascinating to see the sources of biogenic derived aerosols and have presented so visually the seasonal variation associated with both particle size and aerosol character.  It was interesting to see nucleation taking place out at sea with particles 'grown' some 1500km offshore from the Mace Head Atmospheric Research Station measurement site on the coast of Ireland, then being picked up by instruments measuring in the micron range, together with more local nucleation events with particles recorded in the sub-10 nanometer range.  It was also surprising to me that the Mace Head monitoring station had been collecting data for over 50 years.

Dr Ben Murray - Glassy aerosols and their role in ice cloud formation
A very entertaining review of a 'new' form of aerosol matter, glassy materials or very high viscosity fluids (like glass) with a non-crystalline structure.  The example shown of a slurp of Golden Syrup chilled in liquid nitrogen to form a brittle fluid visualised brilliantly, for this simple soul, what was being discussed.
The physics behind this was certainly interesting and the lack of re-crystallisation at low humidity / low temperature was fascinating.  I loved the use of highly technical equipment, an 'allen key', used to shatter the glassy droplets formed in a Raman spectroscopy experiment and then to see the AIDA Cloud Chamber in Karlsruhe (Palas GmbH being based in Karlsruhe) again being used to form these aerosols simulating the upper atmosphere and demonstrating what a novel and capable facility this is.
I wonder whether other applications of this material type may be developed in the future, apart from developing a better understanding what is going on in cloud formation.

Dr Evgenia IIyonskaya - Eyjafallajokull Volcano 2010: Volcanic ash in the atmosphere during and after the eruption
I have to confess to this presentation being my favourite and a good one to finish the day with.  Some fantastic photos, amazing stats and a reminder to all of the impact of a single natural event on a huge region of the developed world, which we were powerless to do anything about.  Tens of tonnes per second of material were being pumped into the atmosphere, with up to 7% as particles smaller than 1um!  The plume reached over 7km and was carried in the winds of the upper troposphere / lower stratosphere towards central Europe resulting in air traffic disturbances.
An interesting and worrying aspect is that even now, over one year on, re-suspended ash is still causing health concerns in Iceland.  This is apparently an unprecedented situation in Iceland and therefore no indication can be made of when this threat will reduce.  I think that it was surprising to most of the audience that this re-suspension issue continues to present problems to the Icelandic people.

My thanks to the organisers and presenters and we will see what is reported in developments at the next meetings.

If you are interested in aerosol science then can I recommend the Aerosol Society and the IOP's Environmental Physics Group .

Tuesday, 29 March 2011

What a week that was at Filtech 2011 !

Well, back in the office after the Filtech 2011 show last week in the lovely city of Wiesbaden.

It was an excellent three days with what has been reported as an increase in visitors again since the last show, coming from all over the world.  It's a long time since I've been stood on a stand and seen sales people operating virtually non-stop, so I'm sure that my partners at Palas will be very satisfied with the show outcomes.

Personally, it was great to see so many of my colleagues again from over 20 years of being involved in the filtration industry.

It was also a surprise to see a film crew on the stand, but apparently a German TV company were making a short piece on Palas at the show.  My mum will be proud to know that I managed to get my face on the telly (being 'demonstrated to') and I'm waiting for the film from my colleagues .... to prove it.

The show itself was full, with all stands occupied.  My over-riding impression from the show was the number of Asian companies showing their products at this year's show.  From non-wovens to woven wire mesh to finished pocket and panel filter products, with the booths being very well presented, rather than what I've seen before which may be perhaps a little lower in quality.  A sign of the times I think?

Being a Physicist and perhaps a bit geeky, the star of the show for me was a desktop electron microscope, which when demonstrated took less than 2 mins for sample prep, followed by operation like a coffee machine with the stud and sample loaded at the front of the unit.  Excellent quality, reasonable resolution and at approx. €60K ...every home should have one !  With a low cost sputtering system this really is a step forward in small scale visualisation for particles, fibre structures, membranes, loaded media etc.

As for the Palas stand, the equipment on display was virtually under continuous use.  Having offered testing on the stand, this became a bit of a double edged sword, the customers being highly impressed with seeing their medias tested in front of them, but with some bringing their entire portfolio for assessment and requiring continuous testing activity!  The MMTC 2000 Cleanable media tester and the MFP 3000 flatsheet tester were perhaps the two most occupied.

New for the Filtech show was an expansion to the Nano range of equipment.  Two new instruments were launched:

  • The DEMC 1000 / 2000, a differential electrical mobility classifier, is based on an already well validated design. The DEMC (also known as a DMA) proved a hit on the stand, with much interest generated with being able to retrofit with other manufacturers CPC's to form an SMPS.
  • The U-SMPS (scanning mobility particle sizer) combines the new DEMC with the novel and patented UF-CPC Condensation Particle Counter, which allows the use of a range of fluids from water to the more common solvent butanol.  Changeover of fluids is easy and the instrument allows control of temperatures in the evaporator and condenser to offer improved sensitivity.

That makes a pretty complete range of nano instrumentation and bodes well for the future.

All in all, a good few days spent in the company of like minded individuals and highly recommended for anyone interested in filtration application and technology.