The BS Viscosity Cups is a range of anodised aluminum viscosity cups with integral nozzle. Suited for measuring paints, lacquers and other fluids.  (Note: the cup doesn’t have a  stainless steel insert).
According to (old type) BS3900: Part A6, 1971. This specification is replaced by BS EN ISO 2431/8S3900 part A6:1996 – see BS EN ISO 2431 series of cups.
 
Note
The BS Cups have been superseded by BS EN ISO 2431 series of cups.
The cups were originally designed for a flow time range of 30 – 300 seconds (break point*1 method) and 30 – 200 seconds (for fixed volume*2 method).
*1 Break point: The timing is taken at the first break in the continuous flow of the sample.
*2 Fixed volume: For this method the cup is filled as normal, but timing is stopped after a fixed volume (50ml) of sample has passed through the cup orifice.
For optimum performance it is recommend to use the cups within a flow time range of 30 – 100 seconds, (table above refers) using the cups for sample flow above 100 to 300 seconds is not recommended as the linearity is not proportional to higher viscosity products.
Cups can be supplied with Calibration Certificates