Every magazine or locker will have at least one direct reading thermometer. It will be located where maximum space temperature variations will normally occur. It must be installed so it is readily accessible for taking  readings  and  resetting  the  index  pointers. Special   brackets   are   available   to   mount   the thermometer where it can be protected from accidental damage. View   A   of   figure   5-5   shows   the   internal components of the device. The temperature-sensitive element  is  a  single  helix  low-mass  coil  (bimetal element) that fits closely inside the thermometer stem. The bimetal element is carefully sized and aged for lifetime stability and is covered with a fluid to assure good heat transfer. The fluid also permits maximum speed  of  response  and  reduces  pointer  oscillations caused by outside vibrations. The case and stem are made   from   stainless   steel   for   strength   and anticorrosion protection. View B of figure 5-5 illustrates the dial face of the thermometer.  It  is  3  inches  in  diameter.  A  plastic window protects the index pointers. The index reset arm is on the outside of the window and is used to reset the high-low pointers. Temperature gradations on our example  are  marked  off  in  20°   increments.  The approximate readings on this thermometer are 100° F, high; 78° F, present; and 55° F, low. After you record these temperatures, reset the “high” and “low” pointers in line with the “present” pointer. As temperature rises during the day, the “present” pointer pushes the “high” pointer up the scale. As temperature falls during the night,  the  “present”  pointer  reverses  direction  and pushes the “low” pointer down the scale. As the sun comes up, the “present” pointer again moves up the scale.  Thus,  we  see  three  different  temperature readings.  They  reflect  the  temperature  variations throughout a 24-hour period. The 45°  spread between the high and low pointers in our example is a bit large. However, it could happen. The reading you must be cautious about is the 100° F high.  When  this  occurs,  you  should  turn  on  the magazine  cooling  or  ventilation  system.  If  these systems  are  not  working,  you  might  have  to  use artificial cooling (fans, blowers). Topside lockers may require cooling with water. Remember, the optimum temperature should be around 70° F. A magazine temperature record card (fig. 5-6) is located  in  each  magazine  and  is  posted  near  the thermometer   for   recording   daily   magazine temperatures. These cards are replaced on the first day of each month. The completed cards are removed from the magazine and the temperatures for each month are posted in a permanent log. The magazine temperature cards must be retained on file for a period of one year. When magazine temperatures are recorded in the permanent log, temperatures in excess of 100° F must 5-14 POINTER GAUGE DIAL POINTER STEM PROTECTIVE TUBE BIMETALLIC ELEMENT MOUNTING CASE INDEX RESET MECHANISM INDEX RESET ARM HIGH TEMPERATURE INDEX POINTER PRESENT INDICATING INDEX POINTER LOW TEMPERATURE INDEX POINTER 120 140 20 240 FCf05005 A B Figure 5-5.—Bimetallic maximum and minimum thermo- meter:    A.  Internal  components;  B.  Dial  face  and pointers. DATE MAXIMUM MINIMUM INITIAL COMPARTMENT THERM. Number MONTH 1 3 2 4 5 6 29 30 31 MAGAZINE  TEMPERATURE    RECORD 5ND GEN  90 (REV 11-48) P&PO N or Va 11-2-48 99014 (J c 8) 8M FCf05006 Figure 5-6.—Magazine Temperature Record Card.