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Online Viscosity Systems. Multi-curve Referral. Temperature Vs. Kinematic Viscosity: ASTM D341. log.log ( v + 0.7) = A-BlogT v = kinematic viscosity; cst T = temperature deg Kelvin. using ASTM D341 log.log (v + 0.7) = A-BlogT. two process variables kinematic viscosity (cst)
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Online Viscosity Systems Multi-curve Referral
Temperature Vs. Kinematic Viscosity: ASTM D341 log.log (v + 0.7) = A-BlogT v = kinematic viscosity; cst T = temperature deg Kelvin
using ASTM D341 log.log (v + 0.7) = A-BlogT • two process variables • kinematic viscosity (cst) • temperature (OK) • two constants A & B • therefore with two sets of calibration data.... A&B can be found
Calculations log.log (v + 0.7) = A-BlogT........(i) let v = 128.58cst at 40 OC log.log (129.28) = A-Blog(313).............(ii) let v = 15.00 cst at 100 OC log.log (15.70) = A-Blog(373)...............(iii) (ii) - (iii) and solve for B: B=3.24 substitute B in (ii) and solve for A log.log (15.70) = A-3.24log(373).............(iv)
calculating base viscosity • now substitute A and B in (i) • log.log (v + 0.7) = 8.41-3.24logT........(v) • and now: • enter the temperature of interest in T, e.g. 50 OC, the base temperature • find v • log.log (v + 0.7) = 8.41-3.24log(323) • v = 80.0cst at 50 OC
the multi-curve method • for products where quality changes dramatically • for multiple products • combines ASTM equation with ratio technique • for bunker monitoring and blending control
Heavy Fuel Oils Calibration Curves Product Curve Viscosity Temperature
The viscosity at the base temperature Find the calibration curve viscosities at the base temperature and then apply the ratios to find the viscosity for the process curve a Find the Ratio of calibration curve viscosities at the process temperature to the measured value Viscosity measured at process temperature b a a b b determining base viscosity Logarithmic scale