Def-Stan 91-091 new release

The 28th September the new version has been issued of the Def-Stan 91-091 Issue 10, that defines two important updates regarding the testing of jet fuel.

Def-Stan 91-091 new version

The 28th September the new version has been issued of the Def-Stan 91-091 Issue 10, that defines two important updates regarding the testing of jet fuel.

In note 15 it is stated that the unique two automatic method accepted are ITR (Annex C-AD System DR10) and ETR, further more it is stated that in case of dispute between two results the automatic metrological method will be the reference.
 
Note 15: The annexes referred to in Table 1 and this note correspond to those in IP 323. If the technically equivalent ASTM D3241 test method is used, the same protocol shall be followed using the appropriate annex that corresponds to the visual (VTR), interferometric (ITR) or ellipsometric (ETR) method. Tube deposit ratings shall be measured by IP 323 Annex C ITR or Annex D ETR, when available. If the Annex C ITR device reports “N/A” for a tube’s volume measurement, the test shall be a failure and the value reported as >85 nm. Visual rating of the heater tube shal l  be by the method in IP 323. Annex B is not required when Annex C ITR or Annex D ETR deposit thickness measurements are reported. In case of dispute between results from visual and metrological methods, the metrological method shall be considered the referee.

Nordtest has a full range of instrument dedicated to jetfuel characterization and testing among which the AD System Dr10, automatic instrument based on ITR and unique instrument nowadays available on the market conforms to both method ASTM D3241 and ASTM D1655.

AD System DR10
AD SYSTEMS DEPOSIT RATER DR10 THERMAL OXYDATION STABILITY OF TUBINES FUELS
Il Jet Fuel Thermal Oxidation Test (JFTOT) è utilizzato per misurare la stabilità ad alta temperatura dei combustibili per turbine avio. Il test deve essere eseguito su ogni lotto di carburante prodotto, secondo le norme ASTM D1655 e DEF STAN 91-91. In questo metodo di prova, il carburante viene pompato attraverso il tubo di riscaldamento ad una portata fissa e per un periodo di tempo specificato. Il carburante viene accettato o rigettato in funzione della quantità di deposito lasciato sul tubo di prova. Tradizionalmente, la quantità di deposito sul tubo viene valutato visivamente confrontandolo con una scala di colori di riferimento. La valutazione corretta richiede una significativa esperienza e competenza; tuttavia può essere molto soggettiva.
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