Hydramotion offers a simple and reliable solution for polymer manufacturers wishing to track the molecular weight of their polymers during production.
Molecular weight is an extremely useful control parameter in polymer production, as it indicates the degree of polymerisation and hence the progress of the reaction. Unfortunately, it is not feasible to monitor changes in molecular weight directly in the process.
There are various laboratory methods for determining molecular weight, but they are often labour-intensive and time-consuming. Inevitably, there is a delay between taking a sample from production and obtaining the measurement, risking out-of-spec product.
On the other hand, online viscosity measurement is very possible. It has long been known that there is a direct relationship between the viscosity of a fluid and the molecular weight of its constituents. So by using the Hydramotion XL7 online viscometer to track changes in product viscosity, polymer producers can effectively monitor molecular weight in real time. This enables production staff to spot anomalies or deviations from specification at an early stage, and ensure that any necessary corrective action is taken.
One well known polymer producer required a customised sensor to meet specific process requirements. For this installation the viscometer had to be mounted on a 1½" pipe, so the diameter of the sensing element was reduced from the standard 24mm to just 10mm, minimising disruption to the flow.
During a three-day polymer production run, these typical measurements were taken, which clearly illustrate the close relationship between viscosity and molecular weight.
The natural perturbation in line temperature (red) actually caused a large increase in line viscosity, but, along with a variation in line pressure (brown), this is almost eliminated after the viscosity reading has been corrected for temperature and pressure. The corrected viscosity (blue) shows excellent correlation with off-line molecular weight measurements (green) made in the laboratory.
Continuous real-time viscosity measurement with the XL7 offers a practical, efficient and convenient solution for tracking molecular weight.
Like all Hydramotion viscometers, the XL7 is factory-calibrated to certified viscosity standards traceable to NIST and no recalibration is required. Mounted directly on a tank or process line, the XL7 system provides continuous viscosity measurement with a range of output options for remote monitoring or control. This includes three fully-configurable analogue 4-20mA signals, and a more comprehensive RS485 serial data link.