Ask Sawal

Discussion Forum
Notification Icon1
Write Answer Icon
Add Question Icon

How to check dmf?

2 Answer(s) Available
Answer # 1 #

Dimethyl fumarate (DMF) is a potent allergenic sensitiser that is used for its antifungal properties. It is good at stopping the growth of mould in finished products such as leather couches and shoes. The white crystalline powder is packaged into small sachets, similar to silica gel sachets used to remove moisture. Whilst silica gel is an inert substance that removes moisture, it is not that effective in preventing mould growth in large leather items, hence the use of DMF sachets.

DMF sachets are found stapled to the wooden frame or directly under the leather covering of couches. They are also placed directly into packaging such as shoe boxes. Although finished leather goods hold very little moisture and, therefore, not prone to mould, the problem arises when transporting these items between different climates. Confined spaces and humid environments can lead to moisture build-up and mould growth. The crystalline DMF powder works to prevent mould growth by evaporating over time. However, during this process it also permeates the leather goods.

Allergy to dimethyl fumarate Dimethyl fumarate sachet

In DMF allergic individuals, contact with DMF produces classic allergic contact dermatitis. In high enough concentrations it may also cause irritant contact dermatitis. The skin affected by the dermatitis can be severe, red, swollen, scaly and itchy. The rash is often seen on the backs of the legs, buttocks and back of patients who have sat on a DMF-contaminated couch. Hence the condition is commonly known as “sofa dermatitis”. Very low levels of DMF (<1ppm2) can trigger a reaction in individuals who are sensitive to the substance. DMF can permeate fabric so areas of skin covered in clothing may also be affected. Continued and repeated exposure to DMF will lead to worsening of symptoms.

Back in 2006-8 there was an outbreak of furniture-related dermatitis in Finland, UK and France. In some cases the rash was quite severe, resembling mycosis fungoides or septic infections (impetigo), and required hospitalisation. Thorough investigation led to the discovery that all patients had purchased leather furniture prior to developing the dermatitis and all the furniture was traced back to a furniture factory in China whom was using DMF to prevent mould growth.

DMF has also been implicated in foot / shoe dermatitis. In one case the dermatitis started as an acute, sharply demarcated eczema that matched exactly to the contact area of the shoe exposure. The patient had worn a pair of new shoes for approximately 8 hours. The high concentration of DMF produced an irritant contact dermatitis rather than allergic contact dermatitis.

Dimethyl fumarate was declared the Contact Allergen of the Year for 2011 by the American Contact Dermatitis Society (ACDS).

Allergy to dimethyl fumarate: sofa dermatitis Allergy to dimethyl fumarate: sofa dermatitis

DMF allergy is diagnosed by performing special allergy tests, i.e. patch tests. Concentrations of 0.001 to 0.1% dimethyl fumarate in petrolatum or aqueous solution can be used for patch testing. However, due to the high risk of irritant reactions and active sensitization caused by DMF some researchers have recommended concentrations of 0.003% or 0.005% as an upper limit. Currently DMF is not included in most baseline series for patch testing and more studies are required to determine the exact concentration of DMF to be used.

Confirmation of DMF allergy requires the prompt removal of the causative agent and then management as for any acute dermatitis/eczema; this may include treatment with topical corticosteroids and emollients. In severe cases, patients may be hospitalized and treated with systemic steroids.

In the European Union, the use of DMF has been banned since 1998. In January 2009, the European regulators also banned the import of products containing DMF as a result of severe cases of dermatitis caused by DMF in imported products. However, in the United States and Australasia there is no regulation of products containing dimethyl fumarate.

Recently in Australia there have been reports of DMF sachets found in imported children's school shoes. Tests performed by the Council of Textile and Fashion Industries showed that 25% of shoes bought from major retailers contained DMF.

If you have sensitivity to DMF you should clearly avoid any contact with products that may have been contaminated with the substance. Sachets labelled “mould inhibitor” or “anti-mould” are likely to contain DMF and should not be touched. Sachets commonly found in shoe boxes or other packaged goods, labelled “silica gel”, should be handled with caution as it has been discovered that some of these may contain both silica gel and DMF, but are labelled only as silica gel sachets.

Items such as shoes that have been in a box with DMF sachets should be left for several months in the open air before the level of DMF can be considered harmless. Unfortunately, in some shoes DMF may have been incorporated into the structure of the shoe and the evaporation of DMF to reach safe levels may be years instead of months.

It is difficult to avoid DMF as products are not identified as containing the substance. Patients and doctors need to be aware of DMF allergy if unexplained skin reactions occur, particularly if a new item of furniture or clothing has been purchased recently that coincides with the dermatitis. Your dermatologist may have further specific advice, particularly if you are highly sensitive to DMF.

Formula: C6H8O4

CAS number: 624-49-7

Cross reactions:

Appearance: fine white crystalline powder

Pranii Frederik
Answer # 2 #

Diagnosing a failing dual mass flywheel can be a little tricky since most of the symptoms could also mean issues with the clutch itself. A definitive assessment will involve visual inspection of all components, but if you have any of these issues, then your flywheel could be the culprit. Noise. If you hear a lot of rattle or banging sounds from the bellhousing, most likely the DMF has failed. These noises can be very loud and it should be replaced as a soon as possible. Slipping. When a clutch is slipping due to wear or otherwise not being up to capacity to the demand placed on it, you get a burning smell like that of burnt bread and gear oil mixed together. This usually happens first in the higher gears due to the higher gear ratios and increased wind resistance. If you do NOT smell the facings burning up when this is happening, it is your dual mass flywheel that is slipping and it needs to be replaced. Vibrations. These vibrations can usually be felt on the floor of the car and are due to the failure of the springs and other internal components. This leads directly to the flywheel’s inability to dampen the tremors with use and it must be replaced. Again, if you have any of these problems, it's time to visually inspect the clutch and flywheel.

Once you’ve determined that your dual mass flywheel is bad, you have a couple of options:

1. Replace the OE dual mass fly wheel with an OE-spec replacement.*

An OE-spec replacement dual mass flywheel will restore the vehicle's stock performance and feel. The downside, of course, is the cost, as replacement DMFs are generally much more expensive that single mass flywheel conversion kits (if a conversion kit is available, of course).

2. Convert from a Dual Mass Flywheel to a Single Mass Flywheel.

If you have increased the horsepower of your engine or tow heavy or you are interested in long term flywheel durability and minimal repair costs, it is a good idea to convert your dual mass flywheel to a single mass flywheel.

*NOTE: Replacing one OE-spec dual mass flywheel with another is only a viable option if the vehicle's power output levels have remained stock (meaning you haven't modified the engine to produce more power). If you have modified your vehicle's engine to produce more power - or if you are using your vehicle for heavy hauling or towing - you should convert your dual mass flywheel to a single mass. Single mass setups, while generally a little louder (due to gear rollover noise), are more durable and more affordable if they require replacement again in the future.

Like a lot of the parts on the modern automobile, dual mass flywheels are a compromise. On the plus side, dual mass flywheels reduce the torsional vibrations in the driveline and the other related vibration and noises. On the negative side, dual mass flywheels are expensive and more prone to failure than simpler, single mass systems (especially if a vehicle is modified to have increased torque). Single mass conversion kits replace a dual mass flywheel with a simpler, more robust system. While a single mass system will be a bit noisier* than a dual mass system, it will also be more reliable, especially in high torque/low idle rpm applications. *Gear Rollover Noise (aka Gear Rattle): The sound that a manual transmission makes when the gears in the gear box are in neutral and are shaken ever so slightly by the engine. It sounds like a light knocking or growling sound, and has absolutely no negative effect on the transmission’s performance or durability. The Gear rollover noise only occurs when the vehicle is idling and the transmission is in neutral.

At Phoenix Friction Products, we offer a variety of single mass flywheel conversion kits. Some of the kits are offered by the Tier 1 OE clutch manufacturers, and some we engineer and then extensively test. In fact, we test all of the single mass conversion kits in-house, ensuring that these kits are more reliable than the dual mass units they replace. We also work hard to ensure these single mass kits don't negatively impact drivability...our testing procedure and metrics for success are reliability, smooth shifting, no increased pedal effort, and as little noise as possible compared to the OEM dual mass units.

English Broadway