Valmet Optical Consistency Transmitter, Valmet OC, (see first photo below) has gained a deserved reputation for accuracy, reliability, and ease of installation since its introduction four years ago, according to a statement by Valmet, Finland, this week. Now Valmet has introduced three new models for applications that have been particularly challenging for inline optical consistency transmitters in the past. This includes measurement of eucalyptus pulp, recycled fiber, and chemical pulps. 

"Valmet's continuous development expands reliable consistency measurement applications. Sharing the same basic components and modules, each new transmitter has a probe and total consistency measurement method optimized for use in special process environment i.e. recycled fiber," said Heikki Föhr, product manager, Valmet. 

Eucalyptus pulp has different optical properties compared with other pulps, which has led to the design of the special optical sensor and measurement method of the Valmet OCE. Results with the new transmitter in several commercial installations have already been successful in applications where competing inline optical transmitters have failed. A typical application is the control of LC-refiner feed consistency, where improved refiner freeness results and reduced specific energy consumption have been reported.

OCC and RCF processes are a challenge for any measuring device, where sand, metal, and other contaminants as well as non-organic fillers are present. The Valmet OCR features a robust probe to survive the harsh physical environment and a measurement that tolerates the ash variations that prevent the use of other inline optical consistency transmitters. Installations in OCC processes before coarse screening have proved the probe's robustness and the total consistency measurement accuracy is excellent throughout the stock preparation area even with wide ash variations.

 

The Valmet OCR (photo directly above) features a robust probe to survive the harsh physical environment and a measurement that tolerates the ash variations.

The Valmet OCS now features a sapphire window to withstand chemicals used in chemical pulping. All three new transmitters have passive measuring probes, connected via fiber optic cable to the measuring unit, that are temperature and vibration resistant as well as self-cleaning even in the demanding environment of recycled fiber processing. Offering simple and low cost installation, the 12-mm-dia. probe with ball valve also makes insertion and removal possible without special tools or process stop required.