SIGMA 150Ci - Manual (Page 25)

DAILY INSPECTION INSTRUCTIONS
3.4
Figure 3.3 Sealed source in transit mode
Sealed source
Source assembly
Shield
Exposure device
Locking
mechanism
Outlet port Source
guide tubes
Control cable
Remote
control crank
Second, during termination of a radiographic exposure, the remote controls are used to
retract the source back into the exposure device. When the source assembly is returned to
the fully shielded position within the exposure device, the locking mechanism automatically
secures the source assembly, preventing the source assembly from being inadvertently
exposed from the fully shielded position. The automatic securing mechanism allows
movement of the exposure device with the remote controls attached at the job site while
preventing inadvertent exposure of the source assembly.
For the third feature, the controls cannot be removed from the exposure device locking
mechanism unless the source assembly has been returned to the fully shielded position
within the exposure device.
The complete radiography system consists of the radiographic exposure device containing
the source assembly, the remote controls, source guide tubes and collimators (beam limiters)
whenever possible.
The use of multiple source guide tubes must be a combined length shorter than the length
of the remote controls, e.g. if the remote controls are 25ft (7.6m) long, only 3 source guide
tubes can be utilized for a combined length of 21ft (6.4m). This consideration ensures the
source assembly will be fully projected to the source stop (exposure head).
The source assembly must never be projected until the equipment is properly connected and
all personnel have left the restricted area.
Transit mode
Rotating the handle of the remote control crank in the EXPOSE direction (counter-clockwise)
moves the source assembly out of the shielded position in the exposure device and into the
source guide tubes (projection sheaths). (See figure 3.3)
The source assembly is under positive mechanical control using the remote control crank.
The remote controls that are fitted with an odometer to provide an indication of the sealed
source’s position. The odometer reading should never be a substitute for the requirement
and proper use of a radiation survey meter.