Oils Selection Guide

The information below will be of help in selecting the correct oils to characterise a viscometer or to calibrate the following flowcups:

  AFNOR FORD BS ISO DIN SHELL ZAHN

Our Notes on Units may also be useful.

Selection of Oils for Characterising Viscometers

The selection of oils will be governed by the range of viscosities that the equipment is capable of measuring.Our oils can be used for calibration at any temperature in the 20 to 30°C range.

The oils listed in the table below are those that are required to calibrate the specified viscometer throughout its working range. If the viscometer is only used for measurements over a limited range then the oils required for calibration can also be restricted accordingly.

Viscometer Type Oil Numbers
Brookfield (all models) Select to cover working range
Cone + plate 0 – 10 Poise U 0600   U 1000   U 1400   U 1800   U 2000 
U 2200   U 2400
  0 – 20 Poise U 0600   U 1000   U 1400   U 2000   U 2200 
U 2400   U 2600
  0 – 40 Poise U 1000   U 2000   U 22100   U 2400   U 2600 
U 2800   U 3000
Krebs Stormer U 1200   U 1400   U 2000   U 2200   U 2400 
U 2600   U 2800   U 3100

Selection of Oils for Characterising Flow Cups

The following tables list the majority of flow cups in current use together with the oil recommended for characterising them.

These recommendations are based on BS EN ISO 2431:1996, ASTM D 1200 (Re-approved 1999), ASTM 4212-99, BS 3900 A6: 1971 (obsolete), and DIN 53-211: 1987 (obsolete). Obsolete standards are referenced here because they describe cups which are still currently used and are not described in current standards.

Not all flow cups are constructed according to National / International Standards but where possible the table lists the Standard, the equation relating viscosity to flow time and the percentage deviation allowed by the Standard between the measured flow time/viscosity and that calculated using the equation.

  Cup No. Oil No. Cup Equation [1]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow
time
(seconds)		 Allowed Tolerance
Cup type: AFNOR

Standard:
NF.T 30-014 (obsolete)

 4 – No data from standard – –
6 – No data from standard – –
  Cup No. Oil No. Cup Equation [1]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow time [2]
(seconds)		 Allowed Tolerance [3]
Cup type: FORD

Standard:
ASTM D1200-94 (Re-approved 1999)

 1 U 0100 ,  33–40 ±10%
2 U 0200 ,  61–61 ±10%
3 U 0200 ,  33–36 ±10%
4 U 0600 ,  32–35 ±10%
  Cup No. Oil No. Cup Equation [1]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow time [2]
(seconds)		 Allowed Tolerance [4]
Cup type: BS

Standard:
BS3900 A6 – 1971 (obsolete)

 B2 U 0200 146–162 ±2.5%
B3 U 0200 54–59 ±2.5%
B4 U 0600 41–45 ±2.5%
B5 U 1000 42–46 ±2.5%
B6 U 2400 49–54 ±2.5%
  Cup No. Oil No. Cup Equation [1]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow time [2]
(seconds)		 Allowed Tolerance [4]
Cup type: ISO

Standard:
BS EN ISO 2431 1996

 3 mm U 0100 67–70 ±3%
4 mm U 0200 48–53 ±3%
5 mm U 0600 35–38 ±3%
6 mm U 1600 54–60 ±3%
  Cup No. Oil No. Cup Equation [1]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow time [2]
(seconds)		 Allowed Tolerance [4]
Cup type: DIN

Standard:
DIN 53–211 1987 (obsolete)

 4 U 0600 27–29 ±3%
6 – No data from standard – –
8 – No data from standard – –
  Cup No. Oil No. Cup Equation [1]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow time [2]
(seconds)		 Allowed Tolerance [4]
Cup type: SHELL

Standard:
ASTM D4212-99 (2005)

 1 – – –
2 U 0100 49–54 ±20%
2.5 U 0100 30–33 ±20%
3 U 0600 74–81 ±20%
3.5 U 0600 51–57 ±20%
4 U 0600 32–36 ±20%
5 U 0600 17–19 ±20%
6 U 1800 27–30 ±20%
  Cup No. Oil No. Cup Equation [1,5]
V = kinematic viscosity (cSt)
t = flow time (s)		 Typical flow time [2]
(seconds)		 Allowed Tolerance [4]
Cup type: ZAHN

Standard:
ASTM D4212-99 (2005)

 1 U 0100 52–54 ±20%
2 U 0600 45–48 ±20%
3 U 1800 44–48 ±20%
4 U 1800 34–37 ±20%
5 U 2600 70–78 ±20%

Notes

  1. The theoretical flow time should be calculated as follows:-
    1. Measure the temperature (to the nearest 0.5°C) at which the cup is being calibrated.
    2. Refer to the calibration certificate of the batch of oil being used and read off the viscosity of the oil (in centistokes) at the cup calibration temperature (1).
    3. Feed this viscosity (2) into the cup equation to calculate the theoretical flow time (in seconds).
  2. This typical "flow time" is calculated at 25°C assuming that the oil has the average kinematic viscosity quoted in the oils range page. In practice oils are supplied with viscosities within ±5% of this value.
  3. The tolerance for Ford cups is expressed as a percentage of the certified viscosity.
  4. The tolerance for flowcups other than Ford cups is the theoretical flow time expressed as a percentage of the measured flow time.
  5. Please note that ASTM D4212-99 (2005) states that not all Zahn cups are designed to comply with the equations published.