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Notes:
•
The spindle must rotate at least five (5) times before a viscosity reading is taken.
•
The use of AMETEK Brookfield Viscosity Standard fluids in the range of 5 cP to 5000 cP is
recommended for cone/plate instruments. Please contact AMETEK Brookfield or an authorized
dealer if your calibration procedure requires more viscous standards.
•
Select a viscosity standard fluid that will give viscosity readings between 10% and 100% of full-scale
range. Refer to Appendix B for viscosity ranges of cone spindles. Do not use a silicone viscosity
standard fluid with a viscosity value greater than 5000 cP with a Cone/Plate Rheometer. AMETEK
Brookfield offers a complete range of mineral oil viscosity standards suitable for use with Cone/
Plate.
Rheometers as shown in Table E-2. Consult with AMETEK Brookfield or an authorized dealer to determine which fluid
is appropriate.
Interpretation of calibration test results
When verifying the calibration of the DVNext, the instrument and viscosity standard fluid error must be combined to
calculate the total allowable error.
The DVNext is accurate to (+/-) 1% of the range in use when using spindles LV #1-3, RV #2- 6, HA #2-6 and HB
#2-6. When using an accessory device with the DVNext such as Small Sample Adapter, UL Adapter, Thermosel, Spiral
Adapter, and DIN Adapter the accuracy value may be increased. In general the decrease in accuracy will be minimal,
however, it could be as much as 1% for a total accuracy of +/- 2% of the range in use.
AMETEK Brookfield Viscosity Standards Fluids are accurate to (+/-) 1% of their stated value.
Example:
Calculate the acceptable range of viscosity using DVNext RV with RV-3
Brookfield Standard Fluid 12,500 with a viscosity of 12,257 cP at 25°C:
1) Calculate full scale viscosity range using the equation:
Full scale Viscosity Range
Where:
TK - 1.0 from Table D-2
SMC = 10 from Table D-1
Full Scale Viscosity Range
2) The viscosity standard fluid is 12,257 cP. Its accuracy is (+/-)1% of 12,257 or (+/-)122.57 cP.
Total allowable error is (122.57 + 500) cP = (+/-) 622.57 cP.
3) Therefore, any viscosity reading between 11,634.4 and 12,879.6 cP indicates that the Rheometer is operating
correctly. Any reading outside these limits may indicate a Rheometer problem. Contact the AMETEK Brookfield
technical sales department or your local AMETEK Brookfield dealer/distributor with test results to determine the
nature of the problem.
Example:
Calculate the acceptable accuracy for viscosity measurement using DVNext LV with SC4-21 spindle in
Small Sample Adapter at 6, 12, and 30 RPM. AMETEK Brookfield viscosity standard fluid 100 cPs has
an actual value of 101.5 cP at 25ºC.
1) Calculate the full scale viscosity range either by using the Spindle Range Coefficient in Appendix B of "More
M19-2101 REVISION 2.0
D V N E X T R H E O M E T E R - O P E R AT I O N A L M A N U A L
Spindle at 2 RPM; AMETEK
109
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