The formula for calculating the standard outflow time of Tu-1, Tu-4 cups, ISO cups and Ford Viscosity Cups is as follows:
Tu-1, Tu-4 and portable Tu-4 standard solution outflow time calculation
Tu-1
tn=0.053ν+1.0 (t>20s )
Tu-4, Portable Tu-4 :
tn=0.154ν+11 (t>23s )
tn=0.223ν+6.0 (23s≤t＜150s )
In the formula:
tn—calculated value of standard outflow time, s;
ν—standard viscosity value of the standard solution at the test temperature, mm2·s-1.
ISO series standard outflow time calculation
In the formula
tn—calculated value of standard outflow time, s;
ν—standard viscosity value of the standard solution at the test temperature, mm 2 ·s-1.
a, c—conversion coefficient (see the table below)
| Outflow pipe inner diameter/mm | 3 | 4 | 5 | 6 | |
| conversion factor | a | 0.443 | 1.37 | 3.28 | 6.90 |
| c | 200 | 200 | 200 | 570 | |
Ford series standard outflow time calculation
Ford-1: tn = ( ν+17.2 )/0.49
Ford-2: tn = ( ν+25.9 )/1.44
Ford-3: tn = ( ν+15.2 )/2.31
Ford-4: tn = ( ν+17.3 )/3.85
Ford-5: tn = ( ν+24.2 )/12.1
