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Viscometer Model 35 Accessories

Shale Tech Solutions SRL distribuidor exclusivo para la Argentina

Fann offers a complete line of accessories for the Model 35 Viscometer.



Electrically heated sample cups incorporate a precision thermostat for close temperature control.  Operating temperatures up to 200°F (93°C) are reached quickly and verified by an included dial thermometer.  Pins in the base locate and lock to the stage of Model 35 Viscometers.  Made of epoxy-finished aluminum alloy for better heat distribution and easy cleaning.

Part No. 101558383 – Thermo-cup, 115 VAC 50/60 Hz, 2 Amps
Part No. 101558384 – Thermo-cup, 230 VAC 50/60 Hz, 1 Amp


Model DW-3 Calibration Check Kit

DW3 Calibration Kit

Dead Weight calibration checks help maintain the accuracy of the torque measuring system on all Model 35 Viscometers.  Quickly determine the condition of bearings and the accuracy of torsion spring setting.  Kit includes support bracket, spool for bob-shaft, 5 metric weights, spare thread, instructions, and case.

Part No. 207853 – Model DW-3 Calibration Check Kit

Fluid Calibration Check Kit

Check Kit

This check kit is designed for checking the calibration of the Model 35 Viscometer or any rheological instrument.  The kit contains certified viscosity standard fluids (NIST certified) in containers labeled with certification numbers and including temperature/viscosity tables.  Kit contains all required containers, thermometer, and instructions for easily determining the accuracy of any viscosity measuring instrument to ± ½ centipoise in the 20-27°C range, and ± 1 centipoise in the 100-300°F temperature range.

Part No. 207026 – Fluid Calibration Check Kit

Certified Viscosity Standard Fluids

Silicone fluids are the most commonly used standard for verifying calibration of Fann Viscometers and Rheometers. Silicone Standards are Newtonian fluids which are accurate to ±1% of viscosity value. Silicone fluids provide excellent temperature stability and are less temperature sensitive than oil viscosity standards. Fann Viscosity Standards are certified by methods traceable to the United States National Institute of Standards and Technology (NIST). The selection of one or two fluids will normally provide sufficient measurement points to verify calibration of your instrument. All fluids are supplied in 16 oz (1 pint) containers complete with a certificate of calibration and a temperature/viscosity table.

Part No. 207124 – Certified Calibration Fluid   10 Centipoise (cP)
Part No. 207119 – Certified Calibration Fluid   20 Centipoise (cP) 
Part No. 207120 – Certified Calibration Fluid   50 Centipoise (cP) 
Part No. 207121 – Certified Calibration Fluid   100 Centipoise (cP)
Part No. 207122 – Certified Calibration Fluid   200 Centipoise (cP)
Part No. 207123 – Certified Calibration Fluid   500 Centipoise (cP)
Part No. 207126 – Certified Calibration Fluid   30,000 Centipoise (cP) 
Part No. 207125 – Certified Calibration Fluid   100,000 Centipoise (cP)

Click here for a statement regarding shelf life of Viscosity Calibration Fluids.

Torsion Springs

Torsion springs are readily interchanged on all Model 35 Viscometers.  Instruments are normally supplied with the F1 torsion spring, which has a spring constant of 386 dyne-cm/degree deflection and provides a full-scale shear-stress capability of 1,533 dynes/cm² at 300 degrees deflection with the B1 bob.  Other torsion spring assemblies are designed to be integral multipliers of the standard spring and can be used to increase or decrease the shear-stress range and, hence, the viscosity range of the instrument.  Precision drawn, tempered beryllium-copper wire helps ensure the precision, linearity and long service life for these torsion springs, even in adverse environments.

 Torsion Spring Assembly Part Number Torsion Spring Constant k1 
(dyne-cm/deg. defl)
 F Factor  Maximum Shear Stress With B1 Bob (dynes/cm2) Color Code
F0.2 207656 77.2 0.2 307 Green
F0.5 207657 193 0.5 766 Yellow
F1 207465 386 1 1,533 Blue
F2 207658 772 2 3,066 Red
F3 207659 1,158 3 4,600 Purple
F4 207660 1,544 4 6,132 White
F5 207661 1,930 5 7,665 Black
F10 207662 3,860 10 15,330 Orange


The outer cylinder, the R1 rotor sleeve, normally supplied with the Model 35 Viscometer has an open bottom.  The R2 rotor is available for smaller gaps, higher shear rates.  Both the R1 and the R2 rotors are available in closed-end, rotor-cup configuration.  An open-end R3 rotor is available for a larger shear gap.  All Rotor sleeves are constructed of Stainless Steel for long wear and corrosion resistance. 

Part No. 207523 – R1 Rotor Open Bottom
Part No. 207942 – R2 Rotor Open Bottom
Part No. 207943 – R3 Rotor Open Bottom
Part No. 208983 – R1 Rotor Closed End 
Part No. 208985 – R2 Rotor Closed End


The inner cylinder normally supplied for the Model 35 Viscometer is the B1 bob, the standard for drilling fluids and cements and other applications as well.  This bob is made of 303 stainless steel for good wear resistance and is hollow for neutral buoyancy, low rotational inertia and fast response in typical test fluids.  Recommended maximum-use temperature is 200°F (93°C).  Three additional bobs are available and are normally used with the R1 family of rotors.

Part No. 207521 – B1 Bob, Hollow, Stainless Steel
Part No. 207520 – B2 Bob, Solid, Stainless Steel
Part No. 207519 – B3 Bob, Solid, Stainless Steel
Part No. 207518 – B4 Bob, Solid, Stainless Steel

Power Inverter

The inverter plugs into an auto cigarette lighter/power outlet and operates the Model 35 Viscometer to within +/- 0.1 RPM for an hour without significant drain on the battery.  This unit produces 60 Hz to +/- 0.05 Hz from DC sources of 10 to 15 Volts.  The Power Inverter has a capacity of 150 watts.  Model 35 Viscometers require less than 100 watts power.

Part No. 206088 – Power Inverter

Yield Stress Adapter

Yield Stress Adapter

Yield Point is a measurement that indicates how a fluid will perform in specific circumstances. This accessory is a cost-effective method to convert a Fann Model 35 Viscometer into an instrument that readily and accurately measures the yield point of various fluids such as particle-laden fluids, foamed fluids, emulsions, etc.

Part No. 101450793 – Yield Stress Adapter