IGT Laray Automated Viscometer

Measures the viscosity of most viscous materials, especially varnish, high viscous oils and paste printing inks

The IGT Automated Laray Viscometer uses the Falling Rod Test Method and complies with ISO 12644 and DIN 53222.

Method of operation
The nip between the rod and cup is filled with the ink to be tested. After release, the rod passes between two sensors, fixed 100mm apart. The first sensor starts the measurement, the second stops it. The speed at which the rod falls, is dependent on the weight placed on top of it. After the test, data can be reviewed and transferred to a PC by means of a USB stick.

Operating Principle
Viscosity is the internal friction of a liquid in motion, ie the resistance of a fluid to flow. The viscosity is generally defined as the ratio of shear stress σ (Pa) to shear rate ϒ (1/s) and is expressed in Pascal-seconds (Pa.s).

When using the Laray Viscometer – the shear rate is calculated from the time taken for a rod to fall through the fluid being tested and the shear stress can be calculated from the amount of weight applied. Measurement range 2 – 200 Pa.s.

The Laray Automated Viscometer’s software calculates both the shear rate and the shear stress and plots them graphically. The viscosity of the fluid tested is the reciprocal of the slope of the graph. This built-in software is Android based, is intuitive and easy to use – accessed directly from the Main Menu screen.

When the ratio between shear stress and shear rate is constant and being shown graphically as a straight line, then and only then can the viscosity of the fluid can be calculated by the IGT Laray software. This is true for both a Newtonian liquid and a Bingham plastic.

A Newtonian liquid gives a straight line through the graph origin, η = σ/ ϒ.

A Bingham plastic needs a minimum stress, the yield stress σ0 to initiate the flow. If the fluid is a Bingham plastic when the straight line does not go through the origin but crosses the X-axis at a certain point (η = (σ-σ0) / ϒ). This point is known is the yield stress. The yield stress value is also calculated by the IGT Laray software.

Standard Supply:
The IGT Automated Laray Viscometer is supplied with 4 weights (50g, 100g, 200g and 500g) to enable weight selection in 50g steps, within the range of 50 – 1000g.

Options
The Rod and the Collar of the unit can be temperature controlled, by use of an optional thermostatic bath.

The following additional weights are also available:

• Laray rod ca. 130g
• Laray basis weight 50g
• Laray basis weight 100g or Laray ring weight 100g
• Laray ring weight 200g
• Laray basis weight 500g or Laray ring weight 500g
• Laray basis weight 1,000g or Laray ring weight 1,000g

Technical details

• Power supply:   Input transformer 100 – 240 V (3.15 AT) / 50 – 60 Hz
• Instrument Weight: 20 kg Nett.
• Dimensions: 300 x 380 x 480 mm (D x W x H)
• Data output: CSV format