KRA and KRT Retention Measurement

Reliable, damage resistant transmitter
Retention control is important to papermakers due to the large influence it has on paper quality variability reduction. ABB’s ultimate solution for monitoring and control of paper or board machine retention is KPM KRA and KRT Retention Measurement
  • MD variation reduction in:
    • Basis weight
    • Moisture content
    • Ash content
  • Web break reduction
  • Faster grade changes and start-ups
  • Optimization of retention chemicals
Retention Measurement System
ABB offers two options for paper and board machine retention monitoring and control: the KPM KRA sensor measures total consistency and ash consistency, while the KPM KRT sensor is for total consistency only. The measurement range for total consistency is 0-2.0 percent Cs and 0-1.0 percent for ash consistency.
Robust design and construction
The sensor is constructed of 316SS with an unbreakable stainless steel measurement cell, enabling the sensors to withstand harsh environments. The display unit and sensor have protection class of IP65 (Nema 4X) and do not need protective housing to withstand difficult conditions at the paper machine wet end.
Maintenance-free operations
Automatic flushing with water can be included to keep the sensors clean without maintenance. The optical sensor has a 3 mm gap between the lenses, which produces a self-cleaning effect due to the increased velocity. The white water sensor also has self-cleaning due to an automatic backflushing module.
Technical specifications – KPM KRA/KPM KRT retention sensor
Sensor type
Retention sensor with optical consistency transmitter
Measurement range
KPM KRT - Total Consistency 0 – 2.0%, minimum 0.005%, 50 ppm
KPM KRA - Total Consistency 0 – 2.0%, minimum 0.005%, 50 ppm
KPM KRA - Ash Consistency 0 – 1.0%, minimum 0.005%, 50 ppm.
Process temperature
10 - 60 °C (50 - 140 °F)
Process pressure
Max 10 bar (140 psi)
Sample flow rate
Minimum 10 l/min (2.5 gpm)
Process connection
Sample valve, diameter 21,3 mm with 3/4” tube connector
Sample line
Fluorinated ethylene propylene (FEP) recommended; max 4 bar (58 psi)
Output signals
3 × 4–20 mA, active, consistency, ash consistency (KPM KRA) and temperature
Binary inputs
4, closing dry contact, process stop, grade change (2), sampler input
Binary output
1 x closing or opening dry contact for general alarm.
Power requirements
Headbox sensor: 90-264 VAC 50/60+3 Hz; 20 VA
White water sensor: 100-115 VAC or 200-240VAC, 50/60+2 Hz; 800 VA
Ambient temperature
0 – 50°C (32 - 122°F)
Flushing water
Mechanically or chemically purified, temperature 25-60 °C (77-140°F)
Same as sample or max 20°C (68°F) warmer,
Pressure 2–6 bar (30–90 psi)
Sealing water
Needed when sample pump included
Same water will be used for flushing when pump included
Instrument air
Pressure 4 – 8 bar (60 – 120 psi), oil-free
Interconnect cable
From sensor to display unit, Included automatically, 1,0-2,0 meters
Sensor materials
Wetted metal parts AISI 316, Wetted tubing FEP
73/23/EEC, 89/336/EEC, EN 61000-6-4:2001, EN 61000-6-2:2001,
EN 61010-1:2001
Enclosure class
IP 65 (Nema 4x)
Dimensions (L x W x H)
Dimensions: 380 x 765 x 1170 mm (15 x 30 x 46")
WW sensor in inch: (20 x 30 x 46")
Headbox sensor 26 kg (57 lbs) White water sensor 48 kg (106 lbs)