Reliable sampling is one of the greatest challenges in consistency control. In the 1980s this problem was studied in extensive customer tests. Development work based on the results of these trials created a new, revolutionary sampler. Today, Valmet Consistency Sampler (Valmet Nove) and Valmet High Consistency Sampler (Valmet Nove H) are the “de facto” standard samplers in numerous pulp and paper mills around the world.

1. High repeatability

An independent university study showed that it takes no less than eleven ball valve samples to reach the same con dence level as with two samples provided by Valmet Nove. Varying process conditions as well as human factors have a considerable effect on sampling with ball valves. In contrast, Valmet Nove is insensitive to flow variations and reduces variations caused by operator skill and sampling practise. Consistency samples are the only standard when calibrating consistency transmitters and evaluating their operation. Poor sampling complicates and slows down the calibration procedure. It also compromises the correlation and lowers operator confidence, thus requiring more frequent testing and follow-up. In addition, process optimization is based on reliable measurement and controls. Therefore, all actions that contribute to better consistency control are worth the investment. This is why Valmet Nove is the sampler of choice for thousands of users.

2. Never forget safety

There are also other methods than ball valves commonly used for sampling. There are poppet valves with a very large opening, and multi-turn plug valves which not only yield a less than representative sample but provide inconsistent results, as they are greatly influenced by the tester. As is the case with ball valves, safety should be a major consideration when trying to operate these valves. The high process temperatures and pressures can make sampling dangerous, when conventional valves are used for sampling. The piston stroke of the Valmet Nove is adjustable, providing exactly the required flow rate for each application. Moreover, the sample flow terminates where the sample can be handled without unnecessary risk. The Valmet Nove has been designed to take representative samples safely.

3. Representative sample

Sampler performance must not be affected by variations in process conditions. It must also allow installation in the best possible location for optimum calibration. The ideal construction of the Valmet Nove sampler and its backflushing feature combine to ensure representative sampling year after year.

Consistency transmitters are getting smarter all the time, and this opens new possibilities for closer communication between the transmitter and sampler. Today’s Valmet Nove samplers can be equipped with an open/ close detector which enables automatic synchronization of the sampling operation: the transmitter reads when a sample is taken, and stores the measurement result for later analysis or calibration. This function contributes to superior consistency management and process control.