Brookfield accessories for specific situations

The purpose of this chapter is to provide a quick overview of the complete line of Brookfield viscometers and their accessories, and to suggest some methods in which these products may be useful in solving specific viscosity measurement problems.

This information will be useful to those adhering to the three schools of thought regarding viscosity measurement. These devices have been grouped into functional groups so that you can quickly locate those having the most interest for your applications.

• Types of viscometers
• Measuring geometries
• Temperature control
• Small amount of product to measure
• Low viscosity
• High temperatures
• Controlled shear rate
• High shear rate measurement
• Semi-solid pasty products which do not flow
• Dangerous or polluted atmospheres
• In-line viscosity - Process control

Types of viscometers

Brookfield viscometers are available in different versions: analog, DVE, DV1M, DV2T or DVnext

On analog models, the reading is taken by the position of the measurement index on the rotating dial. The digital models are differentiated by their number of speeds, the possibility of having a temperature probe, of recording the measurements, of being connected to a printer or controlled by computer ... In most aspects, analog viscometers and digital are functionally similar. Their operating procedures are identical. They are available in the same viscosity range ranges, accept the same types of accessories, and are considered the same (therefore interchangeable) in most specifications indicating viscosity measurements using a Brookfield viscometer.

Analog models are the most economical of the Brookfield viscometers and are suitable for use in most applications where samples need to be measured over a short period of time or where continuous monitoring of the rheological behavior of the product is not useful. This is because when the viscometer is continuously rotating, readings can only be taken intermittently when the measuring index passes in front of the reading window or when it is necessary to lock the index on the dial and d '' stop the engine to take a measurement.

When viscosity measurements require continuous operator attention, digital viscometers are best suited through continuous measurement and data output (plotter or PC). They can operate on their own for long periods of time, and the loggers provide very precise data on even the most dynamic rheological behaviors.

Many users prefer the digital display which eliminates the interpolations that are sometimes unavoidable when reading on a dial. However, the measurement on a digital viscometer cannot be frozen manually as for the analog model. However, analog and digital viscometers offer the same precision and reproducibility. There are many variations in the ranges of Brookfield viscometers, such as intermediate spring torsional powers, changes in speed ranges, and some various physical modifications. Please consult Brookfield or Labomat Essor for more complete information.

Mobile geometries

All Brookfield viscometers are supplied with a set of spindles suitable for most applications within the viscosity range of the device model.

There are, however, cases where well-defined mobile geometries are required to obtain optimum results. Brookfield has developed a wide range of mobiles to meet these needs. The main ones are described later in this section.

All Brookfield viscometer mobiles are made of 300 series stainless steel to avoid degradation in most applications.

Teflon coated mobiles are available for applications requiring optimum corrosion resistance.

Please do not hesitate to contact us regarding your unusual applications.

Mobiles disc shaped

Called LV standard mobiles (mobiles 2 and 3) and standard RV / HA / HB mobiles (mobiles 1 to 6), these are the mobiles that are conventionally used for measuring product placed in a container of 600 ml or more (radius of 4 cm and more).

These mobiles allow the apparent viscosity of most fluids to be determined precisely and reproducibly. The results obtained can be converted into viscometric functions using a mathematical approach described in the Brookfield AR 82 technical document. See section 2.1.7 for more information concerning the geometries of well-defined shear rates.

Cylindrical mobiles

The LV1, LV4 and RV / HA / HB7 mobile units have a defined geometry allowing the calculation of the shear stress and the shear rate.

For all other aspects, the operating conditions of these mobiles are identical to disc-shaped mobiles. Thanks to the fact that their geometry facilitates mathematical analyzes, cylindrical mobiles are particularly suitable for measuring non-Newtonian fluids. "Cylindrical" equivalents of LV3 and LV4 disc-shaped mobiles can be supplied on request.

Coaxial cylinders

The "coaxial cylinder" geometry is recommended for applications requiring very precise definition of shear rate and stress, particularly when the sample volume is quite small. Several Brookfield accessories feature this type of geometry. They each have specific advantages for particular situations.

These accessories are:

• the Small Sample Adapter (SSA)
• the ULA low viscosity adapter (Ultra Low Adapter)
• the thermosel system
• DIN adapter

Cone / plane geometry

The cone / plane geometry allows measurement of absolute viscosity at well defined shear rate and shear stress. The volume of sample required is very small and the heating of the sample is facilitated. The cone / plane geometry is particularly suitable for advanced rheological analyzes of non-Newtonian fluids. This geometry is accessible with the Wells Brookfield cone / plane viscometers and the CAP series viscometers (see section 2.1.8 for more information).

Helipath mobiles

These T-shaped mobiles, generally used with the helipath accessory with which they are supplied as standard, make it possible to measure pasty products with little or no flow (pastes, gels, creams, etc.).

Temperature control

In order to achieve maximum accuracy and reproducibility for viscosity measurements, temperature control is strongly recommended. The following systems are available from Brookfield:

Thermostatic baths

They allow to thermostate a beaker or to be connected to SSA, ULA, cone / plan accessories. Contact Brookfield or Labomat Essor for more information. Viscometers

CAP 1000 + / 2000 +

These viscometers have an integrated Peltier effect temperature control plate. They allow very rapid temperature regulation. The very small quantity of samples (less than 1 ml) facilitates the viscosity / temperature characterization of the products.

Small sample volume

The standard container for viscosity measurement using Brookfield viscometers is the 600 ml low-size beaker. Sometimes users find it preferable or even necessary to measure smaller volumes of product.

Several Brookfield accessories are available:

SSA low volume adapter

Specifically developed to facilitate measurements of low volume of product, this accessory has a coaxial geometry and has a thermostatable chamber. It is compatible with all Brookfield viscometers. Depending on the size of the mobile and the chamber, the required volume varies from 2 to 16 ml. It allows viscosity measurements from 5 cPs to 10,000,000 cPs at shear rates ranging from 0.066 to 93 s-1. The maximum measurement temperature is 100 ° C.

Low viscosity adapter (ULA)

It has been designed to allow viscosity measurements in ranges below the minimum viscosity applicable to each model of viscometer. When used with its closure cap, the sample volume is 16 ml. For more information, see the section

DIN Adapter

Like the ULA adapter, it was designed for very low viscosity measurements. It uses DIN mobiles to measure in viscosity ranges from 1 cP to 50,000 cP. It is in accordance with DIN 53019.

Thermosel system

It allows viscosity measurements at temperatures up to 300 ° C. It uses a coaxial geometry requiring a sample volume of 8 to 13 ml depending on the mobile used.

Cone / plane viscometers

When the sample volume is extremely limited, it may be necessary to use the cone / plane geometry. It requires a volume of 0.5 to 2 ml depending on the cone used for the Wells-Brookfield viscometer and less than 1 ml for CAP viscometers.

Low viscosity

Each Brookfield viscometer measures a wide range of viscosities. However, it is sometimes necessary to measure viscosities lower than the normal range of the apparatus.

Several Brookfield devices offer this possibility:

ULA low viscosity adapter

This accessory has been specially designed to obtain very good sensitivity for the very low viscosities measured with the LV series viscometers. However, it can be used with other viscometer series, except cone / plane viscometers. When fitted to an LVF or LVT model, it covers a range of 1 to 10 cP at a shear rate of 73.4 s-1 at 60 RPM. This accessory has been specially designed to obtain very good sensitivity for the very low viscosities measured with the LV series viscometers. However, it can be used with other viscometer series, except cone / plane viscometers. When fitted to an LVF or LVT model, it covers a range of 1 to 10 cP at a shear rate of 73.4 s-1 at 60 RPM. The thermosel system is specially designed for the measurement of viscosities of small quantities of For other viscometer models, the minimum viscosity measurable with the ULA adapter is: • 6.4 cP for RVTs • 12.8 cP for HAT • 51.2 cP for HBT. The ULA adapter has a coaxial geometry. The chamber is closed by a removable polyethylene stopper. With the cap in place, the useful volume is 16 ml and it can be immersed in a thermostatic bath for temperature regulation up to 100 ° C. If the cap is removed, it can be submerged in a container of any volume.

SSA low volume adapter

With some mobile / chamber combinations, the SSA allows viscosity measurements below the normal minimum of the device range. Consult the tables given in the Brookfield General Catalog for more details.

With certain mobiles, the thermosel makes it possible to increase the sensitivity for low viscosity measurements.

Wells-Brookfield Cone / Plane Viscometer

The cone / plane viscometer can measure viscosities as low as 0.1 cP. See section 2.1.8 for more details on this instrument.

High temperature

Measuring viscosity at elevated temperatures can be both simple and complicated, depending on the type of sample and the temperature desired. Sometimes it is sufficient to simply increase the distance between the viscometer and the sample by using mobile extensions. For more difficult applications, such as for example the measurement of molten glass, it is necessary to use specific accessories as well as pins made of a metal resistant to high temperatures. In between these two extremes, there are accessories that allow most measurements to be made at elevated temperatures.

The themosel system

The thermosel allows the measurement of small quantity of product in a temperature range varying from 25 to 300 ° C. It is delivered with its accessories and can be adapted to the whole range of viscometers with the exception of cone / plane systems. Used with a Brookfield viscometer, the thermosel system includes a cylinder-shaped mobile, a small chamber, an electric oven in the form of a thermocontainer and a digital display controller equipped with an RTD temperature sensor.

The thermosel system requires the use of low sample volumes - between 8 and 13 ml -, a volume which depends directly on the mobile and the chamber used. It allows measurements at a defined shear rate with a range of 0.08 to 93 s-1.

Thermostatic baths

Thermostatic baths are used for viscosity measurements at elevated temperature. However, the temperature is generally limited to 180 ° C. For more information,

Defined shear rate

For applications where viscosity measurements need to be expressed as absolute values, it is necessary to use a measurement geometry for which values of tension and shear rate can be calculated. Such conditions are possible in the following Brookfield configurations.

Consult the corresponding sections for more information on the subject.

• Cylindrical mobiles
• UL Adapter
• DIN Adapter
• SSA Adapter
• Thermosel system
• Wells Brookfield Cone / Tray
• CAP viscometer

High shear rate

Brookfield viscometers are, by design, relatively low shear measuring devices. The maximum shear achieved with conventional ASTM mobiles is generally less than 100 s-1. Shear ranges up to 300 s-1 can be achieved with the following different accessories: ULA adapter (section 2.1.5), SSA adapter (section 2.1.4), and Thermosel accessory (section 2.1.6). For shear rates greater than 300 s-1 it is necessary to use the Wells-Brookfield cone / plane viscometers, CAP viscometers or R / S, R / S-CPS and PVS rheometers.

Wells-Brookfield Cone / Plane Viscometers

They make it possible to determine the absolute viscosity of small volumes of product (0.5 to 2 ml) at a shear varying from 0.6 to 1500 s-1 depending on the viscometer model and the cone used. The tray is thermostatable for excellent temperature control. Depending on the viscometer model and the cone used, the cone / plane allows viscosity measurements from 0.5 to 7,864,000 cP. No device can cover the whole of this range but the use of several cones makes it possible to cover a wide range. The cones / plan are available in analog or digital version. The thermostatic bath is optional but strongly recommended. Cone / plane geometry is only available with cone / plane viscometers. It cannot be supplied as an accessory or modification to other models of Brookfield viscometers. However, it is possible to use conventional mobiles with cone / plane viscometers. It is then necessary to obtain a rack extension in order to facilitate handling below the viscometer.

CAP viscometers

The Brookfield cone / plane viscometers of the CAP series allow measurements at high shear rates. Multi-speed devices are optimized for R&D and Quality Control applications in the paints, coatings, resins, inks, cosmetics, pharmaceutical and food industries. These viscometers incorporate a temperature-regulated platform and allow measurements of sample volumes of less than 1 ml. The CAP series have automatic positioning of the cone in relation to the plane, an automation of the calibration procedure and are available in two models: CAP1000 + and CAP2000 +. The CAP1000 is a single-speed viscometer: 750 RPM at 50 Hz (900 RPM at 60 HZ). The applied shear is 10,000 s-1 (or 2,500 s-1 depending on the cone) at 50Hz. It is 12000 s-1 (or 3000 s-1 depending on the cone) at 60 Hz. The viscosity ranges covered vary from 0.25 Po to 100 Po, or 0.025 Pa.s to 10 Pa.s depending on the cone used . The CAP2000 is a multi-speed device, the speeds vary from 50 RPM to 2000 RPM. It can generate shear rates ranging from 166 s-1 to 26600 s-1 and covers a viscosity range of 0.1 to 1500 Po (0.01 to 150 Pa.s). The CAP1000 + and CAP2000 + models have the same reproducibility of + - 2 %. The possible temperature ranges are 5 ° C to 75 ° C or 50 ° C to 200 ° C. They comply with BS3900, ISO 2884 and ASTM D-4287 standards. 2.1.9

Semi-pasty materials

Non-flowing or slowly flowing materials such as pastes, creams and gels present special difficulties for viscosity measurements. Traditional rotating mobiles have a tendency to "make their hole" in the product, which results in a progressive decrease in the viscosity value. The helipath system is an accessory eliminating this problem.

Helipath System

The helipath system is a motorized stand on which any Brookfield viscometer can be positioned.

This support slowly raises and lowers the viscometer at an approximate speed of 20 mm / min. A special T-shaped mobile is slowly rotated. The cross of the mobile then always penetrates the fresh product since it describes a helical path in the product. The "hole" effect caused by conventional mobiles is then completely eliminated, which allows a significant measurement of the consistency of the product. A set of 6 T-shaped needles and the attachment system are supplied as standard with the helipath system.

SAA Spiral Adapter

This accessory is of the pump type. It directly measures the viscosity of solder pastes and creams in the electronics, food, cosmetics and pharmaceutical sectors. The spiral adapter consists of a spiral-shaped mobile rotating in the center of a concentric cylinder. This configuration results in continuous pumping of product through the adapter. In this way, the product achieves a stabilized flow level which allows a stable viscosity measurement.

Special accessories

Quick Connect accessory

It was designed to facilitate the positioning and removal of mobiles on Brookfield viscometers and rheometers. It saves time and prevents the operator from clogging and damaging the viscometer axis.The Quick Connect accessory is made of stainless steel and can be used with classic LV / RV / HA / HB mobiles as well as with T-shaped mobile helipath systems.

Mobile extensions

They can be used in applications using conventional mobiles and when it is necessary to increase the distance between the product and the viscometer (up to 180 cm maximum). Type D extensions can be used when the submersion depth is visible. When it is not observable, it is necessary to use type S extensions.