ISO 696-1975 pdf free.Surface active agents — Measurement of foaming power — Modified Ross — Miles method.
This International Standardspecifies a methodofmeasurement of the foaming power of a surface activeagent.
The method is applicable to all surface active agents.Measurement of the foaming power of solutions of readilyhydrolysable agents,however,does not give reliable results,as the hydrolysis products collect in the films of liquid andaffect the persistence of the foam.
NOTE – The persistence of liquid films is very sensitive to thepresence ofparticles ofinsoluble matter. This method ofmeasurement of foaming power should be used only with thegreatest of care，therefore,for measuring the foaming power ofcompositions based on surface active agents of which solution israrely complete.Foaming power is also very sensitive to small variations incomposition. Consequently, theresultsobtained onformulated products should be interpreted with caution.The method is not applicable for measurement of thefoaming power of very dilute solutions of surface activeagents,such as river waters containing surface active agents.Separating funnel of 1 l capacity,consisting of aspherical bulb joined to the. upper end of a tube about200 mm long, having a tap at the lower end.The separatingfunnel carries a mark，150 mm above the axis of the tap,which indicates the lower timit of discharge during the test.The lower end of the tube is cut off strictly perpendicularto its length,40 mm below the axis of the tap. The tap ismoulded, not blown,the hole through the key being ofsufficient diameter (not less than 3 mm) to avoid undueobstruction of the flow of the liquid.
Measuring cylinder of 1 l capacity, complying withlso . . ., with graduations at each 10 ml. The measuringcylinder stands in a water bath fitted with a thermostat, thebath being sufficiently large to accommodate the measuringcylinder immersed up to half its height.Stand comprising a vertical rod, sufficiently longto allow the separating funnel and the measuring cylinderto be held in place.To ensure that the assembly is centredand so maintained during the measurement, the separatingfunnel is held by means of a ring supporting the sphericalpart,and a clamp placed as low as possible around the stemof the separating funnel,near the tap. The measuringcylinder is held in place by means of a screw-clamp withone movable jaw.Meteringtube,stainless steel,70 mm long.1,9±0,02 mm internal diameterand0,3 mm wallthickness. The ends of the tube shall be cut accurately atright angles to the axis of the tube,on a precision tool lathe.The metering tube is a push fit in a steel mounting tube 5to 10 mm long, of internal diameter equal to the externaldiameter of the metering tube,and of external diameterequal to that of the low end of the glass tube of theseparating funnel.The upper ends of the metering tube andof the mounting tube shall be in the same plane. Themounting tube is fixed by means of a short length of thickrubber tube (vacuum tubing) so that the upper end of themounting tube is in contact with the lower end of the glasstube.ISO 696 pdf download.