SECTION 8SENSITIVITY ADJUSTMENT8.1On the fuse panel in the section above the fuses, a self-adhesive label shows 24 smoke detector sectionscorresponding to the possible 24 modules located within the cabinet.8.2This table is used to record the sensitivities of the individual modules during each scheduled service. During eachservice. new measurements are taken and recorded on a fresh label. These readings are then compared to theprevious readings to determine if dust is accumulating within the detector module's housings. The two readingsshould be within 3 millivolts. The smaller the voltage reading. the closer the individual detector is to alarm.8.3The individual values of the various detectors may vary, but a typical maximum sensitivity as shipped would be areading of about 1.5 to 2.5VDC. The actual trip point of the detectors will be in the 7 to 10 millivolt range.8.4Decreasing value of delta V indicates that dust has collected in the receptacle or that paint is peeling. Dustreceptacle. If any white surface is showing, repaint with black vinyl matte emulsion.8.5If the presence of dust causes the reading to approach alarm (trip) conditions, those particular detectors may beadjusted to a reduced sensitivity with a field adjustment potentiometer located on the circuit board within themodule. See Figure 8-3.8.6To measure the sensitivity of the individual detector module, two test receptacles appear on the front of eachdetector module. The voltage reading should be taken by means of high impedence (minimum 5 megohms)digital voltmeter, capable of reading on at least 3-1/2 digits.8.7Polarity is of no importance although test point 1 will normally be positive in relation to test point 2 during standbyconditions. The significant value is the voltage between the two points (delta voltage). This reading can beexpected to be 1000 millivolts or greater in any event and normally as indicated above.8-1
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
