Cannon Instrument Company - Viscosity Standards for Zahn, Shell, and Ford Cups

Viscosity Standards for Zahn, Shell, and Ford Cups

Equations for conversion of kinematic viscosity or viscosity into other viscometric units are given here. All data must be at 25°C. Note that the equations apply only between the minimum and maximum drain times shown.

While the equations in the table below are widely used, the equation v = at - b/t is often more applicable, especially at low flow times and low kinematic viscosity.

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Viscosity Standard		Kin Vis mm²/s (cSt/s)	Zahn Cup		Shell Cup		Ford Cup
Viscosity Standard		Kin Vis mm²/s (cSt/s)	Size	Drain time, sec	Size	Drain time, sec	Size	Drain time, sec
C6 9727-W10	Qty	8.9	-	-	1	52	-	-
C10 9727-W12	Qty	17	1	45	2	35	1	70
C20 9727-W15	Qty	34	1	60	2 2½	64 40	2 -	42 -
C35 9727-W20	Qty	66	2	33	2½ 3 3½	74 46 32	2 3 -	64 35 -
C60 9727-W25	Qty	120	2	48	3½ 4	57 36	3 4	58 36
C100 9727-W30	Qty	230	3 4	27 21	4 5	68 36	4 -	64 -
C200 9727-W35	Qty	460	3 4	47 36	5 6	72 29	5 -	40 -
C350 9727-W40	Qty	850	4 5	62 37	6 -	53 -	5 -	70 -
C600 9727-W45	Qty	1600	5	70	-	-	-	-

Ranges of Viscosity Cups

Cup Number	Equations* where t = Time of flow, seconds v = kinematic viscosity, mm2/s	Drain time seconds		Kinematic viscosity centistokes
Cup Number		min	max	min	max
Zahn Cups (See ASTM D 4212)
1	v = 1.1 (t – 29)	35	80	5	60
2	v = 3.5 (t – 14)	20	80	20	250
3	v = 11.7 (t – 7.5)	20	80	100	800
4	v = 14.8 (t – 5)	20	80	200	1200
5	v = 23t	20	80	400	1800
Shell Cups (See ASTM D 4212)
1	v = 0.226 (t – 13)	20	80	2	20
2	v = 0.576 (t – 5)	20	80	10	50
2½	v = 0.925 (t – 3)	20	80	20	80
3	v = 1.51 (t – 2)	20	80	30	120
3½	v = 2.17 (t – 1.5)	20	80	40	170
4	v = 3.45 (t – 1)	20	80	70	270
5	v = 6.5 (t – 1)	20	80	125	520
6	v= 16.2 (t – 0.5)	20	80	320	1300
Ford Cups (See ASTM D 1200)
1	v = 0.49 (t – 35.0)	55	100	10	35
2	v = 1.44 (t – 18.0)	40	100	25	120
3	v = 2.31 (t – 6.58)	20	100	49	220
4	v = 3.85 (t – 4.49)	20	100	70	370
5	v = 12.1 (t – 2.00)	20	100	200	1200

* While the equations in this table are widely used, the equation v = at - b/t is often more applicable, especially at low flow times and low kinematic viscosity.