CONCLUSIONS
This work has focused specifically on the nitrile elastomer used in the shaft lip seal on the home heating burner pump used in most oil-heated homes in North America . With biodiesel that is not degraded , i . e . has an acid number with meets the current specification for biodiesel blend stock for both acid value and oxidative reserve which serve to minimize the likelihood for acid formation during use , no significant impact of the biodiesel on the elastomer was observed at blend levels to B100 . This is based on time periods and temperatures which could be considered conservative relative to those used in practice for material qualification . When the acid number of the biodiesel blend was elevated through the addition of decanoic acid , significant impact on the elastomer was observed . While today ’ s ASTM specification have been designed to prevent such degradation , severely degraded biodiesel with acid numbers above 2 could lead to accelerated degradation of seal materials . l FON
Figure 1-9 Impact of elevated acid number on tensile strength . B-100 .
Editor ’ s note : Next month ’ s issue of Fuel Oil News will include an excerpt on evaluation of oil burner pumps under operating conditions .
Figure 1-10 Impact of elevated acid number on hardness
Figure 1-7 Impact of biodiesel content on measured compression set
Figure 1-11 Impact of elevated acid number on compression set .
Figure 1-8 Impact of biodiesel content on measured volume swell Figure 1-12 Impact of elevated acid number on swell
36 FEBRUARY 2019 | FUEL OIL NEWS | www . fueloilnews . com