The Fisher Cups have all the advantages associated with a precision laboratory cup. There are both Standard and Dip Cup versions available and they have removable orifices that are interchangeable.
Download Excel Viscosity Chart HERE
The Fisher series of viscosity cups as originally designed and produced, provided some advantages over other existing dip viscosity cups. They accommodated a larger sample of the test material. The orifice was considerably longer than its diameter resulting in cup efflux time more closely proportional to viscosity. However, there were deficiencies in the design. The cup was difficult to clean. It was costly to produce and to calibrate. A damaged or enlarged orifice resulted in necessity for replacement of the entire cup.
The Gardco/Fisher viscosity cups retain the original internal cup dimensions and the same orifice length and diameter but with the following improvements: The weight of the new cup has been reduced to 44% of the weight of the original cup for easier temperature control when cup and material are not at the same temperature. The orifices are of the readily replaceable type permitting coverage of the complete viscosity range with one cup and interchangeable orifices. The orifice may be readily replaced if damaged rather than requiring replacement of the entire cup. The design of the lower portion of the cup eliminates hard to clean areas. The design directs the flow of all test material from the outside of the cup away from the efflux stream improving cup accuracy. Rod supports are designed and secured to the cup in a manner to prevent drainage to the inside of the cup and to provide easier cleaning. In addition to physical improvements, the cups are furnished with conversion formulas and a table which relates the nearest tenth of a second of total efflux time to viscosity in centistokes. This table is particularly useful in determining efflux time in seconds when viscosity in centistokes is known.
The Gardco/Fisher viscosity cups are calibrated at time of manufacture to within 2% of target efflux time. This calibration is with standard oils traceable to the National Institute of Standards and Technology. At an additional cost any cup/orifice combination is available with a CERTIFICATE OF CALIBRATION. The procedures and conditions of calibration on which the certificate is based qualify under ANSI/NCSL Z540 or ISO/IEC 17025, ISO 9001, as applicable, & conforms to ISO 9000 when ordered with certification.
The Gardco/Fisher cups are produced to very close mechanical tolerance in elaborate jigs and fixtures. Such equipment not only insures that each cup is correctly produced but also that all cups are identical. All parts of the cup are of stainless steel except for the orifice and the name plate.
|Orifice No.||Seconds Range||Centistoke Range||Midrange Sensitivity¹||Calibration Oil No./Centistokes²|
|1||22 - 60||11 - 48||0.9||G 20 / 35|
|2||14 - 60||19 - 136||2.5||G 35 / 68|
|3||10 - 60||35 - 320||10.3||G 60 / 117|
|4||10 - 60||167 - 1125||19.0||G 200 / 468|
|¹ Centistoke Values are Nominal - Actual Values Printed on Bottle Labels.|
² Stated as Centistokes per Second of Efflux Time.
Fisher Dip Cup Construction
The body of the cup is machined from solid bar stock stainless steel. Note the conical opening for the orifice which permits gentle “tapping in” or “tapping out” of the orifice. Also note that the cup shape ensures that materials draining from the exterior of the cup flow away from the orifice.
Stainless steel rods supporting the cup are formed so that they are held a distance away from the cup. The pad formed at the end of the support rod is welded to the cup below the cup rim. This design prevents any test material from the rod flowing to the inside of the cup. The increased separation of the two support rods also makes it easier to clean the cup.
The orifices for the cup are machined from brass with the exact conical exterior to match the opening in the base of the cup. Positive orifice identification is assisted by “steps” at the base of the orifice.
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It is helpful and results will be more consistent if all viscosity determinations are made in a room that is free from drafts or quick temperature change and is within ±3° C ( ±5° F ) of the viscosity measuring temperature of 25° C.
Fisher Dip Cup Instructions
Fisher Standard Cup Instructions