What is an FDMS? The FDMS is a self referencing airborne particulate monitor based on TEOM technology. The TEOM uses first principle physics to measure the mass of particles collected on a filter. The FDMS measures the core and volatile fractions of the collected mass by using a self referencing technique to measure the effects of these materials as they collect on the filter. Core particulate matter has an additive effect whereas semi volatile materials can both add mass as they arrive on the filter and can later lose mass as they volatalise. Gases and vapours (including water vapour) can also have both positive and negative effects on the mass of the filter and collected PM over time. The FDMS is able to monitor and report these changes (or filter dynamics) as they occur and provide a more accurate and 'true' measurement of airborne pariculate mass concentration. Back to top
What does FDMS stand for? FDMS is an ancronym for Filter Dynamics Measurement System. This is a registered trade mark of Thermo Electron corporation (RP Products)
Air Monitors are the UK official distributor of these products. Back to top
Does this mean my existing TEOM monitor is no good? NO, The TEOM monitor has always given consistent measurements of airborne particulate mass however as the basic model is heated it can drive off volatile substances (such as ammonium nitrate) which are (at least partially) collected by the European standard samplers leading to a difference in the reported mass concentration. DEFRA have stated that they regard the TEOM as acceptable for use in Local Authority Air Quality Monitoring but do reccomend that whereever possible you should endevour to use monitors that are fully equivelent to the European Standards such as FDMS. You can also upgrade most existing TEOM monitors to FDMS. Back to top
Can I upgrade my existing TEOM monitor and what will it cost? Most existing TEOM monitors can be upgraded to FDMS. All Model 1400AB units can be upgraded but some require a flow controller upgrade also to allow for the different flow configuration. If you are unsure if your monitor is upgradable then please complete the form on the FDMS section of this website or refer to the technical help document on the subject in the resources section. The cost will normally be between £6,000 and £7,000 for the upgrade including installation but excluding VAT. Back to top
What size is the FDMS and will my monitoring site be able to accomodate it? The FDMS does add height to the existing TEOM monitor and you may have to lower the position of the existing sensor unit in your monitoring site. (See FDMS schematic and dimensions document in resources area)This is usually done by fitting a lower shelf to support the unit or placing it on a plinth on the floor. The existing inlet and roof flange should be reusable but we suggest you have a site survey before going ahead. Air Monitors offer this service free of charge to customers upgrading with us. Back to top
What about continuity of my data set with my existing TEOM? The FDMS gives both core PM mass (base) and total PM mass (base + reference). The base measurment is very similar to the measurement of PM with the basic TEOM system and therefor a certain continuity of monitoring data can be expected as advised by DEFRA. Back to top
Can I trade in my old TEOM or other monitor for a new FDMS system? YES. We offer a generous trade in for most old PM monitors (not just TEOM's) and will credit any offer agreed against the cost of a new TEOM-FDMS system. Back to top
Can I use any other type of monitor to measure PM ? YES, The Partisol Model 2025 sampler also passed the equivalence tests. However this is a garvimetric sampler and does not provide real time data like the FDMS. The filters have to be sent for analysis in a laboratory and the sampler requires more attention than the FDMS often making it a more costly option in the long run. Other automated monitors also passed the test however to use them you also need to apply either an offset factor a slope factor or both. The FDMS is the ONLY monitor which requires no factors for either PM10 or PM2.5 used anywhere in the UK. Back to top
How do I tell if my TEOM has 1st or 2nd generation flow controllers? The first generation flow controllers make a clicking sound in operation which the 2nd generation flow controllers do not. Please refer to the guide "FDMS Upgrades - How do I tell what I need?" in our FDMS Resources Section Back to top
Can I buy FDMS upgrades from anyone other than Air Monitors ? YES. Air Monitors is the exclusive distributor of the TEOM - FDMS in the UK. However you can buy the system from a number of sub suppliers who in turn buy from us , however we have many years experience in the development, uply, installation and support of the system and can guarantee to provide you with a trouble free service from start to finish. Back to top
Will FDMS affect my data logging system ? The FDMS communicates in a similar manner to the TEOM and therefor if you are currently logging data from the TEOM the FDMS will operate in much the same way. There will be more data and the time basis is slightly different as the system has effectivly two channels but this is easily managed by most software systems. If you wish to upgrade then Air Monitors offers AQWEB which is fully compatable with the FDMS and most gas monitors allowing fast data logging and management over an internet connection. It is not expensive and can save you money on communications and reduce visits to site. Back to top
Can I measure Black Carbon with the TEOM - FDMS YES. The TEOM FDMS can be fitted with an optional Aethalometer system allowing the simultaneous measurement of black smoke (black carbon). Back to top
Can I get a copy of the full DEFRA PM Monitoring equivalence test report? Yes this is available to download at the above link and at www.airquality.co.uk run by AEA NETCEN. Back to top
Where can I get independant advice on FDMS and PM monitoring? There are several helplines (funded by DEFRA and the devolved administrations) available to local authorities and other air quality professionals at www.airquality.co.uk run by NETCEN, and at www.uwe.ac.uk/aqm/review/mfaqpm.html run by University of West England. Back to top
Can I compare the specifications of the FDMS and other PM monitors? YES. In our FDMS resources section you can download a chart of manufacturers published data on most common PM monitors. Back to top
What Monitors are used in the UK National Network? The TEOM and TEOM-FDMS arethe most prevalent monitors in the AURN networks and DEFRA has recently invested in additional FDMS systems. Back to top
