Normalab VTW Classic Viscometer Tube Washer

Cleaning capillary viscometers in solvent vapour

The VTW Classic is a Normalab automatic washer for glass capillary viscometer tubes. Each tube is suspended in solvent vapour at a selected temperature, so the vapour condenses and runs through and over the tube, washing it inside and outside. Clean tubes matter because even a thin film of old oil or residue changes flow time and therefore the viscosity result in ASTM D445 work.

Normalab lists ASTM D445, ASTM D446, ISO 3104, ISO 3105 and IP 71 and related methods. The leaflet says the washer is designed to clean the tubes described in those standards and that other tubes or standards used for viscosity measurement may not be cleaned the same way.

Technical specifications

Delivered items and options

The VTW Classic is delivered with six injector stoppers (P/N 18454). The options named in the leaflet are a recommended solvent (P/N 25714), chosen for shipping conditions, safety and health, and sold as BIOSANE on the web page, and a chiller (P/N 23203) that condenses the vapours and recycles the solvent more efficiently.

Because the washer condenses and reuses solvent, consumption is negligible according to Normalab, and operator exposure to liquid solvent is lower than when tubes are rinsed by hand with wash bottles.

Where the washer fits in a viscosity laboratory

A viscosity laboratory that runs many ASTM D445 tubes a day, for example with an NVB Classic bath and several Ubbelohde or Cannon-Fenske tubes, spends much time on cleaning. The VTW Classic shortens that step to between 5 and 15 minutes for up to six tubes at once, and it lets tubes be reused sooner.

After washing, tubes still need to be dried and inspected before reuse, and each laboratory should keep to the cleaning and drying steps given in its viscosity procedure. Solvent vapour installations should sit under extraction or in a well-ventilated room, with the solvent charged and drained according to the safety data sheet. Before ordering, confirm the tube types, the solvent you plan to use and its local availability, the chiller or cold water supply, and the 230 V, 16 A outlet. Related equipment is grouped under liquid analytical systems.

Because the VTW Classic holds up to six tubes, laboratories with a larger viscometer inventory often keep one washer next to the bath and run a wash cycle while the next set of samples is being prepared, which keeps the bath busy.

Related Normalab products: Normalab NGT Classic Existent Gum Tester for Fuels, Normalab NVB Classic Kinematic Viscosity Bath, Normalab GWM Classic Automatic Grease Worker, Normalab NGT Classic Existent Gum Tester (ASTM D381), Normalab NTB Classic Copper Strip Corrosion Test Bath and Normalab NTB Classic Copper Strip Corrosion Bath (ASTM D130).

Documents and quotation

The Normalab VTW Classic leaflet is attached. Send the tube types, solvent and options required for a quotation; availability and lead time are confirmed before ordering.