Viscometer Searle's Pattern

Product Code : EL-EAST-10422

Specifications

How the viscosity experiment is done

Searle's viscometer measures viscosity from the couple needed to turn one cylinder steadily inside another. The liquid fills the gap between the outer cylinder and the inner cylinder. Weights in the scale pans drive the inner cylinder round; the liquid resists by viscous drag, and the cylinder soon turns at a constant rate.

For a gap between radii a and b and an immersed length l, the viscous couple is G = 4 pi eta l omega a^2 b^2/(b^2 - a^2), where omega is the steady angular speed. The ends of the cylinder add an unknown extra drag, so the run is repeated with two different immersed lengths; the millimetre graduations and the height-adjustable outer cylinder make this easy, and subtracting the two results removes the end effect.

1. Fill the outer cylinder with the liquid and clamp it so the inner cylinder is immersed to a known depth, read on the mm scale.
2. Place equal weights in the scale pans and hold the cylinder with the releasing pin.
3. Withdraw the pin, let the cylinder reach a steady speed, then time a set number of revolutions.
4. Repeat with different loads, then change the immersed length and repeat to correct for end effects.
5. Calculate eta from the couple and the steady angular speed.

Key features

• Outer cylinder clamps at any desired height to vary the immersed length
• Inner cylinder graduated in millimetres for direct depth readings
• Transparent cover over the reading slot protects the scale
• Releasing pin holds the cylinder until each run starts
• Supplied complete with scale pans for the driving weights

Documentation and supply

Most Lab Exports products carry a one-year manufacturer warranty.

Lab Exports manufactures the Searle's viscometer at its works in Laxmi Nagar, Delhi, and supplies it to schools, colleges and universities in India and 60+ countries, handling the export documents for each shipment. More about the company is on the About Lab Exports page.

Related Elasticity and Surface Tension products

• Viscosity Apparatus Stokes Method (EL-EAST-10421)
• Surface Tension Apparatus (EL-EAST-10420)
• Searle's Surface Tension Balance (EL-EAST-10419)
• Quincke's Surface Tension Apparatus (EL-EAST-10418)
• Rising Table with Capillary Tube Clamp (EL-EAST-10417)
• Capillary Tube Clamp (EL-EAST-10416)

The full range is in the Elasticity and Surface Tension section of the Physics Lab range.

Frequently asked questions

What is Searle's viscometer best suited for?

Measuring the coefficient of viscosity of very viscous liquids, such as glycerine or heavy oils.

How does it differ from the Stokes' method apparatus?

Stokes' method times a falling ball, while Searle's viscometer measures the steady rotation of a cylinder under a known couple, which suits liquids too viscous for convenient ball timing.

What accessories are included?

Scale pans and a releasing pin are supplied with the apparatus.

What is the price of the Searle's viscometer?

Prices are not published on the website. Add the Searle's viscometer to the Enquiry Cart with the Add To Cart button on this page, or email [email protected] with the house code EL-EAST-10422 and the quantity, to receive a quotation.

Does Lab Exports manufacture the Searle's viscometer?

Yes. Lab Exports manufactures the Searle's viscometer at its works at 11/315, Lalita Park, Laxmi Nagar, Delhi 110092, under house code EL-EAST-10422.

Request a quote

Email [email protected] with the house code EL-EAST-10422 and the quantity, or add the Searle's viscometer to the Enquiry Cart with the Add To Cart button on this page. Tender buyers can also see the Tenders and OEM page.