Very heavy radiation protection sliding door requires control unit with special safety parameters
Industrial computed tomography is being used more and more frequently. It enables the non-destructive testing and detection of defects in components. This improves the quality and efficiency of manufacturing processes. On the other hand, however, this requires appropriate safety precautions to protect all people working in these areas. The CT scan room must be securely enclosed by a radiation protection gate. In order to prevent radiation from penetrating outside, radiation protection doors are very heavy due to their lead coatings. This means that there are very high safety requirements for motorized movement of the door. In addition, the safety precautions due to CT scan operation must be observed and implemented.
The radiation protection door meets the necessary safety requirements with the help of the SQUARE 940-2 control unit.
SQUARE 940-2 control unit allows for the required safety settings
The radiation protection door was equipped with an operator that had not been supplied by DICTATOR. Subsequently, the company was looking for a control unit that would meet all the requirements for trouble-free and safe operation. The DICTATOR operator control unit SQUARE 940-2 proved to be the ideal solution.
- The SQUARE 940-2 control unit is so flexibly programmable that it also works with third-party operators.
- For this radiation protection door, the operator required two separate inputs in the control unit to process different EMERGENCY STOP commands. According to the Machinery Directive, the door must stop immediately without delay in the event of an EMERGENCY STOP. In this case, the two safety contact strips (both in the OPEN and CLOSE directions) were connected in accordance with the regulations. Independently of this, however, a second EMERGENCY STOP was also required. If a separate emergency switch is actuated, the sliding gate must also stop immediately and the entire system is switched off.
- Inside the CT scan room, the door may only be operated with an OPEN and a STOP switch, as no one must be able to close the door there for safety reasons.
- Outside, the door can be opened by briefly pressing the OPEN button (impulse mode). A stop button is also available. This allows the door to be stopped before it is fully open. The door may only be closed in dead man’s mode, i.e. the door only closes as long as the CLOSE button is pressed. If it is released, the door stops immediately.
- The operator uses limit switches for the OPEN and CLOSE positions to detect the position. A further limit switch just before the closed position is used to reduce the travel speed so that the door travels more slowly in the last few centimetres before the CLOSED position and does not collide with the door frame without braking. There was no need for a fourth limit switch to reduce the speed before the OPEN position, as the control unit calculates this position automatically. This also reduced the installation costs.
- Only when the door is completely closed and a corresponding signal is issued by the control system can the CT scan begin in the sealed-off room.
Related projects
Motorized opening and closing of heavy hinged radiation protection doors?
State-of-the-art operator control unit also talks to old door operators
Hinged door operators must be impervious to dizziness
