Oscillating U-tube technology for reliable measurement
Krüss offers two models of Density Meters, designated the DS series. Models DS7800 and DS7900 have a compact measurement cell with high resolution, measuring density specific gravity and concentration of liquid solutions by the oscillating U-tube method. Both devices allow a cost-effective operation with low wastage of samples.
Features & Benefit
- High accuracy and resolution.
- User-friendly touchscreen (with six language options), all results and user management can be operated on the device. The unit incorporates an integrated SQL database for storing data, and allows for access via a network or standalone PC.
- Cost-effective with low wastage of samples.
- Full GLP suitability and NIST compliance.
- Integrated Peltier thermostat.
Both DS7800 and DS7900 models utilise oscillating U-tube technology – the glass U-tube is monitored through a window to ensure no gas bubble falsifies the results. All important settings are visible on screen and stored in a SQL database (the last 999 measurements are stored). User-friendly, the DS7800 and DS7900 have a selection of programmable measurement units, an integrated Peltier thermostat, a desiccation unit and peristaltic pump. These are NIST and ASTM compliant and have full GLP suitability.
For prices and availability information on the DS series Density Meters, please contact your nearest Krüss distributor, who will be delighted to help.
For full technical specifications, please download the DS7800/7900 brochure here.
How does an oscillating U-tube work for density measurement?
Measuring the density or specific gravity of a fluid may seem a simple enough task, involving just the weighing of a sample of known volume and a bit of straightforward arithmetic. In practice, the oscillating u-tube makes this operation reliable, repeatable, and highly accurate.
The phenomenon of the resonant frequency is well known: any object, if allowed to vibrate freely, will do so at a specific frequency. An empty wine glass will generate a note at a particular pitch, but a different one when filled with wine. What is less easy to detect by ear is that it will make a different note again when filled with water, or with oil. The density of the fluid determines the specific pitch, and so it is with the oscillating U-tube. The precision glass tube has known harmonic properties, which vary according to the density of the fluid it contains.
The advantages of the oscillating U-tube over other specific gravity measurement techniques are many. The automatic density meter requires only small sample sizes, and with an inbuilt Peltier element will accurately control sample temperature – which otherwise would have major effect on accuracy. Calibration is quick and easy using dry air and pure water, and the highly accurate density readings can be integrated with process or laboratory management systems. Testing is fast and clean, especially when compared to ‘wet’ density analyses such as pyknometer or hydrometer, improving laboratory productivity and providing a safer and cleaner lab environment.
