Consistency measurement

Consistency measurement for the paper industry is certainly one of the strength points of Valcom production, a well-known brand of Terranova. The measurement is critical and requires high precision because it significantly affects the final quality of the product, a requirement of modern production plants. Terranova measures consistency with the family of products called T7C, which includes electronic paper pulp consistency transmitters with 4÷20 mA output and HART digital communication protocol.

The operating principle consists in the detection of the cutting force generated by the interaction between the blade sensor and the fibers contained in the paper pulp: this force is acquired and compensated in temperature, providing the value of the paper pulp consistency on the display.

The typical operations required at the startup phase are:

1. mounting the instrument on the process;

2. starting the plant (the pulp is set up to the desired consistency);

3. taking a sample of pulp while performing a “freeze” operation on the T7C to store the value of the output signal at the moment the sample was taken;

4. analysis of the pulp sample by the laboratory which determines the consistency value of the dough;

5. entering the consistency value into the T7C instrument to complete the sequence.

The T7C series provides up to 4 different profiles in which to save the relative configurations: the operations can be performed directly from the instrument using the 4 keys on the display or via our HART® compatible configuration software.

The output signal proportional to the cutting force varies based on the ranges that can be set digitally directly on the instrument and on the consistency value set during calibration, so as to be able to read the consistency of the dough flowing in the pipe (recycled paper, short or long fiber cellulose, wood pulp, etc.) showing the consistency percentage directly on the display and/or acquiring the 4÷20 mA/HART output signal.

The T7C instrument is always supplied with a series of mechanical accessories resulting from decades of experience in the paper pulp consistency analysis sector, including different types of blades and various connections for mounting the instrument on any type of line.