KxS Retractable refractometer DCM-20 PASVE®
With KxS Technologies – the former K-Patents experts, customers trust our decades of expertise. KxS Retractable refractometer DCM-20 PASVE® is designed carrying forward the same deep pulp industry application knowledge.
The refractometer features the proprietary PASVE® isolation valve, an industry standard since the 1980s with over 75,000 units installed worldwide.
The DCM-20 PASVE® design provides secure connection to the process, maximum operator safety and simple, risk-free sensor insertion and removal without process shutdown.
The most maintenance-free pulp industry refractometer
KxS DCM-20 PASVE® is engineered to last longer than any other pulp industry refractometer without maintenance. It detects true buildup on prism, eliminating excessive prism washes and prism erosion, extending the equipment lifespan.
Optical stability like no other
The KxS DCM-20 PASVE® is built with advanced CMOS-based optics and 6th generation optical image recognition, meaning the signal noise ratio is very good. This leads to more precise and reliable measurement even in the most challenging applications.
Universal sensor for all applications
Our solutions are tailored to meet the specific measurement and safety requirements of each stage in the kraft chemical recovery and fiberline processes. No need for multiple models. All DCM-20 PASVE® sensors are interchangeable, covering the full R.I. range of 1.32…1.56 and all pulp mill dry solids content measurement applications up to 85 %.
- Weak liquor from pulp washers
- Black liquor to evaporators
- Black liquor to recovery boiler
- Green liquor TTA in causticizing
- Fiber line filtrates in Brown Stock Washing
Key industry benefits
- Improved safety with patented PASVE® valve and 4-layer safety system
- Compact footprint (400 x 400 x 300 mm) for easy retrofitting and tight installation areas
- Real fouling detection via proprietary optical software – reducing wash frequency and maintenance
- Maintenance-free system: ideal for high-solids, scaling, and corrosive applications
Purpose-built systems for kraft pulp mill applications
KxS offers three specialized DCM-20 PASVE® system configurations, each engineered to meet the specific demands of applications with the highest level of optical reliability. The DCM-20 PASVE® system for black liquor in evaporators and recovery boilers is our most widely used configuration.
DCM-20 PASVE® system for black liquor consists of:
- Retractable refractometer DCM-20 PASVE® sensor
- PASVE® Isolation valve
- Prism wash system with steam
- Modular connection unit MCU with wash relays
Other system variants are for:
- Green liquor: designed to resist heavy scaling and maintain accurate readings using prism wash with hot condensate water
- Brown stock washing filtrates: optimized for suspensions with abrasive content and minimal wash needs
All pulp mill applications are covered with same interchangeable sensor, reducing complexity in spare unit management.
Patented KxS DCM-20 PASVE® safety design
KxS has designed the DCM-20 PASVE® system with patented safety features to protect both your process and your personnel. At the heart of the system is the PASVE® isolation valve, a field-proven solution trusted by the pulp industry with over 75,000 installations worldwide.
Four independent safety layers safeguard operator and prevent unintended sensor removal:
- Sensor safety stopper
- Safety guide
- Safety clamp
- Safety thread
Optimal footprint, easy installation
The DCM-20 PASVE®, with its compact design, offers exceptional flexibility for choosing installation points in vertical and horizontal pipe lines within the pulp mill. Its small footprint ensures easy integration into various setups, optimizing space and service efficiency.
What makes DCM-20 PASVE® practically maintenance-free?
KxS DCM-20 PASVE® system is designed to operate longer and more reliably—with virtually no need for routine maintenance. This is a result of expertise, smart engineering, and advanced optical performance tailored for the toughest pulp mill conditions.
Future-ready solution for full BLRBAC compliance
DCM-20 PASVE® is designed in alignment with the BLRBAC (Black Liquor Recovery Boiler Advisory Committee) good recommended practice for the safe firing of black liquor recovery boilers. Integrated divert system, a key BLRBAC safety recommendation, is part of our product roadmap, and will also soon enable full BLRBAC compliance for mills that require it.
Key features
- Durable, industry-proven construction withstands high temperatures, scaling, pressure fluctuations, and chemical exposure.
- Most modern CMOS-based optics is accurate, and stable without sensitivity to light scatter.
- Advanced 6th generation image detection identifies only real fouling, triggering wash cycles only when truly needed. This reduces unnecessary washing that can cause prism erosion.
- Nozzle made of SAF2507 super duplex stainless steel for superior wear resistance and fully embedded in the hot process zone, maintaining high temperature and preventing clogging.
Reliability. Expertise. Personal service.
At KxS, we know that reliable process measurement goes beyond the refractometer itself. It requires a combination of expert guidance, precise installation, and tailored support to meet the unique challenges of each application.
Whether you are working with black liquor, green liquor, or brown stock washing filtrates, choosing the right components and installing them correctly is essential. That is why we offer dedicated expertise throughout the entire lifecycle of your DCM-20 PASVE® system—from configuration and installation to optimization and long-term support.
Process connections
- 1.5” tri-clamp connection, Varinline® and APV tank bottom flange.
- Optional flow cell housing connections with sanitary or DIN/ANSI flanges.
Optimizing the Kraft pulping process requires precise monitoring of critical process streams, and the KxS Retractable refractometer DCM-20 PASVE® plays a key role in ensuring efficiency and stability.
In brown stock washing, where the separation of cooking chemicals from pulp fibers is crucial for chemical recovery, the DCM-20 PASVE® provides real-time data to help mills optimize washing efficiency and reduce chemical losses.
Moving further into the recovery process, the refractometer ensures accurate black liquor concentration measurements before evaporation, preventing excessive viscosity and enabling efficient energy use. Similarly, in the recovery boiler feed, precise monitoring of black liquor solids helps mills balance combustion efficiency with equipment longevity.
Beyond these key process stages, the DCM-20 PASVE® contributes to improved green liquor clarification by providing real-time dissolved solids measurements before recausticizing. This ensures a well-balanced chemical cycle and minimizes scaling issues in the white liquor preparation process.
Throughout the mill, the ability to make real-time process adjustments based on reliable in-line refractometer data leads to reduced chemical and energy consumption, enhanced product quality, and improved environmental performance.
Instrumentation and installation considerations
Inline measurement sensors used in black liquor Dry Solids and green liquor Total Titratable Alkali (TTA) applications face extreme process conditions that can challenge measurement stability and reliability. These challenges vary depending on application and include high temperatures, pirssonite scaling, lime mud and calcium deposits, high pressures, process fluctuations, and chemical aggressiveness.
Refractometers used in these demanding environments must be purpose-built to withstand turbid, high-solids process fluids, which can scatter light and interfere with accurate measurement if not properly engineered with the right optics and advanced optical image detection software.
In black liquor applications, organic carryover and dissolved lignin can create a sticky residue on the sensor prism, impacting measurement reliability. In green liquor applications, heavy scaling can result in excessive build-up on the prism, which compromises accuracy. Purpose-built self-cleaning systems are critical to ensuring stable and reliable readings and trouble-free operation over time.
Measuring suspensions and filtrates during Brown Stock Washing (BSW) presents own kind of challenges. Standard retractable refractometers are not suitable for these applications. While automatic prism washing is rarely required, filtrates often contain fine sand, dirt, and residual wood fibers, which can be abrasive and damage the prism if the sensor is not properly shielded with mechanical protection to withstand these harsh conditions.
Why choose KxS for pulp mill applications?
KxS has over 40 years of expertise in pulp and paper industry applications. This deep knowledge ensures that the DCM-20 PASVE® retractable refractometer is purpose-built to perform reliably in these challenging environments. Every aspect of its design considers the specific process conditions, fouling tendencies, and operational safety requirements.
KxS does not focus solely on product specifications, but delivers both superior technology and in-depth process expertise, making KxS the leading choice for reliable refractive index measurement in Kraft chemical pulp mill applications.
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