Model 4525 Radiation Portal Monitor Installation Manual Section 1
Ludlum Measurements, Inc. Page 1-1 October 2018
Overview
The Ludlum Model 4525 Radiation Portal Monitor or “gate monitor” is designed
to detect very low levels of radiation, typically in vehicle loads as they are driven
between the detectors. Usually the radiation detectors are placed right before a
weigh scale. This manual is intended to assist you in the installation of the system.
Several different models and options are available. In general, the full model
number tells the number of detectors – the Model 4525-7000 is a two-detector
system, the Model 4525-10500 is a three-detector system, and the 4525-14000
system has four detectors. Each detector contains approximately 57,355 cm3(3500
cubic inches) of plastic scintillator. These are also other systems available, like the
Model 4525-2400, which has four 9832 cm3(600 in3) detectors.
The detectors are normally mounted to the side of the vehicle, and also sometimes
above the vehicle. The detectors are centered around the typical load; your situation
or location might require the detectors to be higher or lower than the dimensions
shown in the back of this manual.
Each system comes with a wall-mount computer display, printer, and universal
power supply (UPS). This computer logs data and displays the current status of the
system. It is typically placed inside the scale house, or in close proximity to the scale
operator. A remote display, with status lights and a reset button, is also provided.
The remote can show the status and allow someone to reset alarms whenever the
main computer is inaccessible. It is typically placed in the scale house, or sometimes
under a weather-protected porch.
Each system uses infrared sensors to detect the vehicle’s presence, and thus switch
from measuring the background radiation to checking for an alarm. Multiple sets of
sensors are used to measure the speed of the vehicle and to ensure that the vehicle
presence is sensed throughout the passage of the vehicle. The range of vehicle sizes,
from flatbed trailers to tall drop-off boxes, necessitates some care in positioning the
sensors. The drawings in the back of the manual suggest some mounting heights
that have worked at many locations.
Take a moment to review the block diagrams that are located at the back of this
manual (Drawings 511 x 420 and 511 x 420A). Compare those drawings with the
system that you have purchased or are about to purchase. The block diagram may
help you to understand the available options. You can also use the block diagram to
locate where at your location the different components will be situated.
