fig1 shows a fan - supported gas mask and breathing equipment , in which a filter adapter 2 and a gas filter 3 are connected , one behind the other on the suction side , to a fan housing 1 . a fan drive 40 , indicated by a circle drawn in broken line , delivers the ambient air according to the flow arrow 4 in the direction of an outlet - side respiration gas hose 5 , through which the filtered ambient air is delivered via filtered air connection 100 into a breathing mask 6 . the mask 6 has an eye - protective lens 7 and an exhalation valve 8 , and can be tensioned over the head of a mask user , not shown , via a strap 9 . the fan housing 1 has a filter connection 10 with a recess 11 serving as a connection marking or connection identification means , into which corresponding pin 12 forming filter identification means of the filter adapter 2 , acting as filter marking , extends . the adapter 2 has , on the suction side , a threaded insert 35 , into which a screw thread 13 of the gas filter 3 is screwed . the connection lines between the housing 1 , the adapter 2 , and the filter 3 , which are drawn in broken line , indicate the movements which are necessary for assembly of the individual components shown . fig2 shows schematically the filter housing 1 , and it shows a perspective view of the filter connection 10 with an inlet opening 41 for the filtered respiration gas to be delivered from the environment . the housing 1 has the recess , designed as the connection identification means 11 , into which the corresponding filter marking or filter identification means 12 , designed as a round pin , extends . the filter marking 12 is provided with a magnetic strip 14 , which actuates an electric contact accommodated in the housing 1 , e . g ., a reed contact 15 , when the markings 11 , 12 engage each other . due to the closing of the contact 15 , the fan output necessary for flow through the filter insert 16 is set in a microprocessor , not shown , which is accommodated in the fan housing 1 . on its housing surface 17 facing the inlet opening 41 , the filter insert 16 carries the filter marking , which in turn consists of the round pin 12 provided with the magnetic strip 14 , on the one hand , and , on the other hand , a square pin 22 , the latter of which is received in a corresponding recess acting as a sensor marking 18 in the fan housing 1 . the recess 18 and the square pin 22 together provide sensor identification means providing information from the filter insert 16 as to what is to be detected by sensor 44 . the pin 22 forms an information source element and the sensor marking 18 forms an information receiving element upon engagement with the pin 22 . the square pin 22 is provided with the magnetic strip 14 ( as the information source ), which actuates , in the inserted state ( inserted into sensor marking 18 ), an electric reed contact 23 , represented by broken line , as a result of which a detection sensor 44 belonging to the filter insert 16 will be actuated . the sensor marking 18 with the corresponding detection sensor 44 is adjusted to the filter material 19 contained in the filter insert 16 . a measuring pipe opening 43 and a pressure pipe opening or pressure channel 42 , which lead to the gas sensor 44 or a pressure sensor 45 , respectively , are also arranged in the filter connection 10 . a filter cover 20 , which is provided with a perforation 21 on the suction side , is placed over the filter insert 16 . the cover 20 serves to mechanically protect the filter insert 16 . fig3 shows the same the fan housing 1 as does fig2 which contains the filter adapter 2 , which also carries the filter marking 12 , 22 on corresponding flaps 31 , in its circumferential area 32 . the adapter 2 is provided with a flow opening 33 , through which the ambient air , purified in the gas filter 3 , flows into the inlet opening 41 of the fan housing 1 . the filter adapter 2 also has a threaded insert 35 for screwing in the gas filter 3 with its screw thread 36 . the gas filter 3 has a filter opening 37 toward the atmosphere . the surface of the fan housing at the filter connection 10 , facing the adapter 2 and the gas filter 3 , carries three reflection photocells 46 , which are arranged next to each other and consist each of an led as a light source and a photodetector acting as a receiver . this structure provides a gas type decoder which is a further part of the sensor identification means . the leds emit light to reflection strips 50 , which are arranged concentrically on the end face 47 of the gas fan housing at the filter 3 facing the filter connection 10 , as is shown in fig4 . the reflection strips 50 form the gas type coding for the further part of the sensor identification means . the number and position of the strips 50 may be combined corresponding to the type of gas for which the filter 3 is suitable , so that corresponding reflected rays will hit the detectors 46 , and generate an electric signal in them . the information on the gas filter 3 used , thus coded , is sent to the electronic circuit accommodated in the fan housing 1 , so that the necessary fan output will be set , on the one hand , and , on the other hand , threshold values are established , which are important for the gas sensor 44 for sending a warning signal when it measures a gas concentration exceeding the threshold value , which warns of an imminent filter breakthrough . the view of the screw - in filter 3 according to fig4 shows its end face 47 which faces the filter connection 10 and is interrupted by the filter opening 37 and is surrounded by the screw thread 36 . the end face 47 carries two the reflection strips 50 , the distance between which corresponds to the distance between the two outer led / detector combinations 46 ; these emit their light onto the strips 50 , and receive a correspondingly reflected signal . the central one of the led / detector combinations 46 receives no reflected signal . while a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention , it will be understood that the invention may be embodied otherwise without departing from such principles .
a fan - supported gas mask and breathing equipment with a fan unit with adjustable delivery output such that the delivery output of the fan and detection sensor will be automatically adjusted to the necessary filter property , depending on the type of the filter insert used . to achieve this , the filter connection and the filter insert are provided with a marking , which characterizes the filter property , on the one hand , and , on the other hand , actuates electric contacts for setting the necessary fan output and , if desired , for actuating a detection sensor .