FLK Gas Sampling System - MPIP - Free

SQ256 Retraction Device
1.4 Construction
The retraction device basically consists of a runner rail and carriage. The gas sampling probe, dust removal filter
and compressed air valve combination are mounted on the carriage.
- The runner rail is produced from square steel tube. On the bottom of the runner rail there is a mechanically
protected, rigidly mounted and self-cleaning roller chain track which engages the chain-wheel on the carriage. The
runner is mounted with two mounting supports at the beginning and end of the rail. The supports are anchored to
the floor.
- The carriage, consisting of strong pressed parts, is pushed along the runner rail. Guidance is provided by closely
fitting tapered rollers. The tapered rollers have encapsulated ball bearings and are therefore insensitive to dusty
ambient conditions.
- An induction motor with self-locking worm drive drives the carriage. The drive motor is completely enclosed in a
dust-tight, hose-proof housing. Cooling is provided by cooling ribs on its outer surface.
- At the second end of the drive-motor shaft there is a pneumatic auxiliary drive connected via a coupling. When
mains failure occurs, this enables the probe to be retracting from the kiln. Where a compressed air motor is not
present, this function can be handled by a DC motor under battery operation or by a hand crank.
- The end positions of the carriage are defined by adjustable limit switches.
1.5 Mode of operation
The retraction and insertion processes are activated by:
• a manual switch on the retraction device
• a voltage-free contact on the central control panel
• a signal from the programmable logic controller.
The running time for the retraction or insertion process is about 1.5 minutes depending on the length of the probe.
In order to prevent dangerous overheating of the coolant during a power failure or when the flow ceases, the
probe retraction is facilitated by a supplementary auxiliary drive. The auxiliary motor is immediately started,
withdrawing the probe, when one or more phases on the three-phase motor fail. When a pneumatic drive is used,
it is switched off in the retract state via a pneumatic limit switch.
Copyright ® SIEMENS Page 96 04/04