Hi,I am John,now i will continue share ASTM D6890-18,Standard Test Method for Determination of Ignition Delay and Derived Cetane Number (DCN) of Diesel Fuel Oils by Combustion in a Constant Volume Chamber.
A small specimen of diesel fuel oil is injected into a heated, temperature-controlled constant volume chamber,which has previously been charged with compressed air. Each injection produces a single-shot, compression ignition combustion cycle. ID is measured using sensors that detect the start of fuel injection and the start of significant combustion for each cycle. A complete sequence comprises 15 preliminary cycles and 32 further cycles. The ID measurements for the last 32 cycles are averaged to produce the ID result. An equation converts the ID result to DCN (derived cetane number),whichis correlated to cetane number by Test Method D613.
General – This test method uses an integrated automated analytical measurement system comprised of:
(1) a constant volume compression ignition combustion chamber with external electrical heating elements, suitable insulation and pneumatically actuated intake and exhaust valves.
(2) a heated,pneumatically actuated fuel injection system with pump,injector nozzle assembly, and associated sample reservoir.
(3) a coolant system with a liquid-to-air heat exchanger, filter,circulating pump and fLow control valves.
(4) temperature thermocouples, pressure gages and sensors, an injector nozzle needle motion sensor, compressed gas pressure regulators,control valves, pneumatic actuator components, and solenoid valves, and
(5) a computer to control test sequencing, acquireand accumulate sensor signal data, provide processing calculations, and automatically output a printed report of some important test parameters (see Fig. 1).
ASTM D6890-18 pdf can be downloaded on www.freestandardsdownload.com