When vegetable oils self-heat, the first chemical compounds to diminish in concentration are the polyunsaturated fatty acids (PUFAs) such as linoleic and linolenic acids. At high temperatures or under prolonged heating the PUFAs can diminish to the extent they are no longer detectable. The presence of PUFAs in the analysis of fire debris is an essential element in determining whether self-heating is a possibility or not (e.g. ASTM E2881). Once PUFAs have reacted, additional means of characterising the oils or fats present are needed.
Chromatograms of rapeseed oil prior to heating (green) and after heating (red) showing loss of PUFAs (peaks between 24.45 and 29 min)
SMS Analytical have been identifying some oxidation products of PUFAs in fire debris to help us establish whether any oils and fats that are present are capable of self-heating. We are continuing to improve our analyses and interpretation of results to provide more detailed reports for fire-related problems.
Contact us to discuss ways we can assist in fire debris analyses
SMS Analytical have had an increasing number of cases relating to tumble drier fires in the last couple of years but these are not related to electrical faults like those with the subsequent recall shambles seen a few years ago. In these particular cases Fire Investigators pass the remains of semi burnt fabrics on to us for analysis of residual fats/greases/oils.
We provide a comprehensive report detailing any tiny traces found. The fire can be caused by particular chemical reactions of residual oils/fats with oxygen in the air, aided by some heat. I suspect this may be partly because of lower temperatures used in ‘Eco’ wash cycles, leaving traces of residual oils/fats which can lead to auto-oxidation reactions, causing self heating and then increased chances of a fire. Some oils are much more likely to cause this, their class is referred to as ‘drying oils’ and includes Rapeseed, one of the most commonly used cooking oils. Even after the drier has finished there may still be a critical core of heat within a stack of fabrics, containing residual oils, so best open and allow to cool after it finishes.
The general advice is not to overload the washer/drier and ensure a sufficiently high temperature is used to remove all oils before tumble drying and use regularly cleaned lint-trapping filters.
Which have provided a useful guide: Section 5 relates to oils.
Never leave a drier on unattended overnight. Sleep tight!
For more information visit our website https://www.smsanalytical.com or give us a call on +44(0)333 3580037
Image Copyright BBC
A large scale laundry fire was recently reported by BBC, luckily no casualties, but the business will take considerable time to be re-established. No doubt fire investigators are working to determine the cause(s) – self-heating through oils/fats in fabric, lint, electrical or other?
At SMS Analytical we have recently received a number of laundry fire related samples for analysis. The causes of such fires is obviously of considerable interest.
Cotton- and linen-containing fabrics can retain significant quantities of oil even after washing at 40°C. The chemical composition of the oil is important if self-heating is to occur : polyunsaturated fatty acids (PUFA) facilitate self-heating.
Analysis of the fire residues can reveal a fatty acid profile which can give indications as to whether self-heating has occurred. Although once self-heating starts, there is a change in the fatty acid profile of the oils, with preferential loss of PUFAs. The analysis gives a snapshot of the composition of the oil after the fire so other information may be needed to confirm whether self-heating is a possibility.
We are undertaking a series of experimental analyses to get an idea of how quickly the fatty acid profile can change with time and temperature, which will be the subject of a later post.
April 2022: We are delighted that a biopic of our company has been published in Fuel & Oils News magazine and website. The short article as a great summary of SMS Analytical and our supporting motivation.
Read the biopic here.
Here is our new diagram that gives you an overview of the areas of business for which we provide supporting investigative chemical analysis.
We are proud to now be able to offer a range of analyses and consultancy to support the condensing boiler manufacturing industry as they switch from gas and kerosene to alternative fuels such as hydrogenated vegetable oils (HVOs).
Over the last year have been working with a key player in the industry to help show that the newer fuels types are producing condensates that are acceptable.
To check out your boiler condensates for problems we offer a range of analyses is including pH, total acidity, particulate analysis, residual fuel analysis, corrosion analysis as well as selected anions and cations quantification.
See the following page links on our web site for more information boiler condensates, industries
There has been much discussion recently on LinkedIn (see ref 1 and ref 2) about using GC-MS to analyse marine bunker fuels and whether this should be a routine test.
Firstly GC-MS is a fairly generic term covering a variety of techniques within that label such as
- Headspace GC-MS
- Direct Injection GC-MS
- Direct injection GC-MS with derivatisation of the sample
- Sample extraction with or without sample derivatisation GC-MS (“polars” analysis)
All of these will provide some information about the composition of the fuel, but none will provide every bit of compositional information.
Continue reading → GC-MS Analysis of Bunkers
We are very pleased to announce that SMS Analytical Ltd has just renewed its ISO9001:2015 certification following another successful full audit by SGS, our accredited certification body. Our certificate is available for inspection by clicking on the SGS Certificate logo at the top right of our website: www.smsanalytical.com.
Our thanks go to our customers and in particular to those who have helped us prepare for the SGS audit by themselves visiting and auditing us earlier in the year.
We have a new method for the determination of water in various materials.
It is based on the Dean and Stark method and uses a mixture of Toluene and mixture of Xylenes to carry the water over into a graduated receiver vessel where the water appears as a layer below the lighter solvent.
Hint: hover over the following images for zoom in and move around.
Recovery testing using known % of water.
The sample (last image) shows the collected water as lower phase after about 3 hours of distillation. In this case, a very small drop of methylene blue was added to the receiver afterwards to aid the visualisation.
The technique is quite tricky to get right and requires some practise. In order to get a good recovery a long wire can be inserted from the top of the condenser and by twisting the wire against the droplets the water they are encouraged to coalesce and drop to the bottom of the receiver to join the rest of the water. This is illustrated by the tiny remaining traces of blue still on the sides of the receiver in this case.
Exciting news for Christmas: SMS now have a High Performance Liquid Chromatography (HPLC) system to complement the existing range of other chromatographic techniques that we offer our customers.
The HPLC system comprises Pump with ternary solvent input, solvent de-gasser, UV detector, column oven and data system. Future expansion options might include a Fluorescence detector.
Examples of additional types of work we can now offer include:
- Euromarker detection in Gas Oils (e.g Red Diesel) and kerosene
- PAH analysis
- identification of oxidation products from antioxidants used in polymers which can cause discoloration issues
SMS Analytical’s HPLC System