Q83. For diesel fuel (e.g., No. 1 or No. 2 fuel oil) shipments that are received 1 or 2 times a year, is it sufficient to sample the fuel carbon content upon receipt of each shipment for Tier 3?

A83. Yes. If you are using Tier 3 to estimate emissions from fuel oil, analysis of at least one representative sample from each fuel lot is required.  Alternatively, you may analyze a sample taken upon each addition of oil to the storage tank. Flow proportional sampling, continuous drip sampling, or daily manual oil sampling may also be used, in lieu of sampling each fuel lot. If the daily manual oil sampling option is selected, sampling from a particular tank is required only on days when oil from the tank is combusted by the unit (or units) served by the tank.  If you elect to sample from the storage tank upon each addition of oil to the tank, you must take at least one sample from each tank that is currently in service and whenever oil is added to the tank, for as long as the tank remains in service.  You need not take any samples from a storage tank while it is out of service.  Rather, take a sample when the tank is brought into service and whenever oil is added to the tank, for as long as the tank remains in service.  If multiple additions of oil are made to a particular in-service tank on a given day (e.g., from multiple deliveries), one sample taken after the final addition of oil is sufficient. (See §98.34(b)(3)(ii)).