Normalab NVB Classic Kinematic Viscosity Bath

A precision bath for kinematic viscosity measurement

The NVB Classic is a Normalab constant-temperature bath for determining the kinematic viscosity of transparent and opaque petroleum liquids. A calibrated glass capillary viscometer is held vertically in the bath, the sample reaches the test temperature, and the operator times how long a fixed volume takes to flow through the capillary under gravity. The bath’s job is to keep that temperature stable to a hundredth of a degree, because viscosity changes quickly with temperature.

Normalab lists ASTM D445, ASTM D446, ISO 3104, ISO 3105 and IP 71 and related methods. The scope covers transparent and opaque liquid petroleum products measured with calibrated glass capillary viscometers.

Technical specifications

Holders, options and the Chronotech timer

The NVB Classic is delivered with a cooling coil, which Normalab’s leaflet gives for working below 40 °C, and a bath drain. Viscometer holders are necessary accessories and are chosen by tube type: a stainless steel holder for Ubbelohde viscometers (P/N 10567), a nylon holder for Cannon-Fenske Routine and Reverse flow viscometers (P/N 10568), or separate holders for Ubbelohde (P/N 1785200002), Cannon-Fenske Routine (P/N 1785200003) and Cannon-Fenske Reverse flow (P/N 1785200004) tubes. Viscometer tubes are listed on request.

Optional accessories are a plate with 8 openings, lids and a thermometer hole (P/N 23214), an external illuminator for easier reading (P/N 24587), a cryostat (P/N 23206), which is required if the laboratory temperature is above 30 °C, a set of insulated tubes for connecting the cryostat (P/N 60214), black rubber stoppers in packs of 12 (P/N 17433), and a loading and cleaning system on request. The Chronotech (P/N 41900) is a Normalab electronic stopwatch with touchscreen, three independent stopwatches, automatic viscosity calculation and 3 hours of autonomy.

Choosing temperature, fluid and viscometers

Water is normally used near ambient and moderate temperatures, and silicone oil for higher temperatures up to the 230 °C limit, so decide the working temperatures first. Many laboratories run the two common reference temperatures for lubricants, and the cryostat or cooling coil is needed whenever the room is warmer than the test temperature.

Keep the bath level correct, stir as required by the chosen method, and allow each viscometer enough thermal equilibration time before timing. Before ordering, confirm the viscometer types and number of positions, the holders, a certified thermometer or probe, the cryostat, the Chronotech timer, the bath fluid and the supply voltage. The leaflet lists the footprint as 350 x 590 x 585 mm. Related equipment is grouped under liquid analytical systems.

Documents and quotation

The Normalab NVB Classic leaflet is attached to this page. Send the viscometer types, test temperatures and accessories you need for a quotation; availability and lead time are confirmed before ordering.