Abstract: A gas detector is disclosed which includes a CO sensor and a processor. The CO sensor senses an environmental CO concentration and provides a variable electrical output in response. The processor receives digitized samples of the sensor's electrical output and computes, with each measurement sample, a COHb level of a hypothetical person exposed to the CO concentration sensed. The computation involves determining an equilibrium COHb level for each measurement sample, which is compared with a previously computed COHb level associated with previously measured samples. The previously computed COHb level is updated based on the comparison. When the computed COHb level is above a predetermined danger threshold, the processor preferably causes an audible and visual alarm to be activated to alert any persons present. The gas detector can further include a CH.sub.4 sensor coupled to the processor for independently sensing CH.sub.4 levels such that an alarm is activated when the CH.sub.

Abstract: A gas detector is disclosed which includes a CO sensor and a processor. The CO sensor senses an environmental CO concentration and provides a variable electrical output in response. The processor receives digitized samples of the sensor's electrical output and computes, with each measurement sample, a COHb level of a hypothetical person exposed to the CO concentration sensed. The computation involves determining an equilibrium COHb level for each measurement sample, which is compared with a previously computed COHb level associated with previously measured samples. The previously computed COHb level is updated based on the comparison. When the computed COHb level is above a predetermined danger threshold, the processor preferably causes an audible and visual alarm to be activated to alert any persons present. The gas detector can further include a CH.sub.4 sensor coupled to the processor for independently sensing CH.sub.4 levels such that an alarm is activated when the CH.sub.

Abstract: A marking device with a reciprocating needle. The needle is attached to an armature which reciprocates in a slot in a housing by a crank which is rotated by a motor in the housing. Vibration of the motor and tolerances between the armature and track cause unwanted movements of the needle in a plane perpendicular to the reciprocating motion. Guide bars and bushings connect the armature to the track. Tolerances between the guide bars and bushings are less than tolerances between the armature and track. An armature bracket is detachably connected to the housing in order to partially or fully close off an open end of the track after the armature has been inserted into the track. Guide bars and bushings then connect the armature and the armature bracket. The motor is supported on only one end by bolts extending from a mounting wall inside the housing. A damping plate is positioned between the motor and the mounting wall, and a damping ring is positioned between, and contacts, the damping ring and the housing.