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LB 9140 - Alpha/Beta Moving Filter Monitor

Artikelnr.: 55927-01

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  • Si-CAM detector unit 600 mm² for simultaneous separated Alpha-/Beta measurement on a flat dust collection area of 25 x 25 mm²
  • Direct measurement of air borne alpha-beta activities with radon compensation (ABPD & AERD)
  • Optional gamma compensation-detector
  • Integrated alarm functions (pump, filter paper, thresholds, signal column, etc.)
  • High air flow of 3.3 m³/h
  • Filter tape autonomy up to 3 months at 5 mm/h velocity
  • Transportable due to low weight (approx. 43kg) and small dimensions

With the mobile moving filter monitor LB 9140 airborne alpha and beta activities in room and exhaust air can be monitored with high sensitivity. Due to the silent and low maintenance pump unit an air flow rate of approx. 3.3 m³/h is possible.

The portable monitor consists of following main building blocks:

Dust collection unit 9140µ
allows the prompt measurement of radioactiv particles emitting alpha or beta using Si-CAM detector

Prompt Alpha-/Beta detector
measures directly on the collection area to have a real time monitoring system

Cassette
made of aluminum with protection degree IP68 envelopes the dust collection unit, filter supply and take-up spools. A plexi- glass front door allows visual inspection of the filter supply on the feed spool.

The filter advance is driven by a stepper motor unit, which allows continuous advancement of the filter tape at user selectable speeds (5/10/12.5 and 15 mm/h). Alternatively the filter can be advanced in step wise mode with user selectable time intervals. 
Pump Unit: with linear motor-driven Free Piston System (Pat.) has an internal piston inside the cylinder which is driven by an electro-magnet and spring system controlled by the alternating input current cycle. The system is quiet and vibration free, and offers the advantages of easy maintenance and a long operating life. The nominal flow is 3 m³/h with a noise level of max. 60 dB(A) at 1m. Optionally a flow meter can be offered.

Si-semiconductor Alpha-/beta detector
with 600 mm² surface and ruggedised entrance window for simultaneous, separate measurement of Alpha- and Beta activities. The detector analog signal is converted in the LB2029-40 amplifier unit into 3 norm pulse signals and an analog output suited for spectroscopy (ADC) input.

Optional second Si-semiconductor detector
with 600 mm² (or 150 mm²) surface can be used for ambient gamma radiation compensation. This guard detector is mounted on top of the prompt Alpha-/Beta detector to obtain identical geometry and the analog signal is converted in the LB2029-41 dual amplifier unit.

Analog/Digital counting electronics
LB 5340 data logger unit process the signals coming out of the amplifier. The electronics makes use of intelligent front end analog/digital modules and communicates with these via internal CAN-Bus. LB 5340 contains 3 intelligent front end modules:

  • Pseudo coincidence board ABPD
  • Multi I/O board
  • 8 fold Relay board

The monitor is equipped with self-check routines that continuously monitor the system health and alarm status:

  • Monitoring of the Pump function
  • Monitoring of the Filter tape
  • Detector Failure threshold Alpha and Beta (and Gamma if installed)
  • Pre-Alarm Threshold Alpha or Beta
  • Alarm Threshold Alpha or Beta
  • Lamp test

Filtercassette

Structural shape                

300 x 300 x 530 mm³ (W x D x H)
elapsed hour counter
flow low and filter trouble indicators (led)
fast filter advance pushbutton
reset filter timer push button
plexi door for access wetted parts

Dust collectionarea

25 x 25 mm²

Wetted parts mat´l

Ni plated brass to MIL stdrd / stainless steel

Construction mat´l

Alum side & back plate, plexi cover front

Sampling section
from inlet to filter

to DIN 25423 (06/96) stainless steel RS 316L

Pressure

Ambient
Sample

650 to 1100 hPa
max. -150 mbar / +25 hPa to
atm. pressure

Temperature

Ambient
Sample

-15 to +40 °C
-20 to +40 °C

Humidity                                

Ambient
Sample

0 – 95 % RH non condensing
0 – 95 % RH non condensing

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Filter

Type 

Glas fibre Particulates filter to DIN Whatman
N° 10, roll 12 m x 50 mm, core 25 mm dia

Advance

continuous
speed selectable 5/10/12.5/15 mm/h
fast 1000 mm/h pushbutton frontpanel

Autonomy

> 3 months at 5 mm/h speed

Controls                               

Filter ruptured, Filter supply low (< 3 m)

 

 

 

 

 

 

Pump Unit

Pump                     

low maintenance (> 10 000 h)
silent operation (< 60 dB(A) at 1 m)
pump head max -440 mbar
typical operating -160 mbar

Flow rate

typical 3.3 m³/h at NTP

Controls                         

pump head pressure switch (flow low)
typical set point 3.2 m³m/h at NTP

 

 

 

 

 

 

 

Alpha-Beta Detector

Type

Si-CAM 600 m² light tight

Typical efficiencies
solid sources



 

Alpha

241Am

25% / 4 pi

Beta


 

36Cl

60Co

 

25% / 4 pi


 

Energy range
(preamp threshold setting)

 

Beta

Alpha

Alpha Nat.

100 keV - 2.5 MeV

2.5 MeV - 10 MeV

7 MeV - 10 MeV

Background in system

 

Alpha

Beta

< 0.02 cps

< 0.2 cps

Leadshield

2 cm / 4 pi

Ambient gamma sensitivity

Beta channel

 

< 0.4 cps per µSv/h 137Cs radiation front
< 0.2 cps per µSv/h 137Cs radiation back

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Guard Detector

Type  

Si-CAM 600 mm² light tight

Background in system

Beta window < 0.2 cps

Ambient gamma sensitivity

Beta channel

< 0.6 cps per µSv/h 137Cs radiation front

 

 

 

 

 

 

Preamplifier

Type                                               

LB 2029-40 (one detector) /
LB 2029-41 (two detectors):
dual preamplifier / discriminator stage
built-in bias voltage generator 0-1000 V for Detector 1 and 2

 

 

 

 

Electronics

Type              

Data Logger LB 5340

 

 

Enclosure LB 9140 / LB 5340

Dimensions                

530 x 300 x 300 mm³ (H x W x D)

Weight

approx. 43 kg incl. pump and cart

 

 

 

 

Cart

Dimensions                         

approx. 1035 x 420 x 395 mm³ (H x W x D)

 

 

Alarm Unit

Type                                             

LB 9140-ALARM, green system healty lamp, orange, red flashing lamps, resetable horn 90 dB(A) at 1 m

Lamps

LED´s 230 VAC WERMA

Functions

Reset horn, lamp test pushbutton

Connections

mains 230 VAC connector,
remote signals DIN T 3406 6 pole male

 

 

 

 

 

 

Overal Electrical Specifications

Mains                              

230VAC/50 Hz/Single phase, I nom 1 A,
Fuse : 1.6 A T, thermal safety 1.3 A