Figure 2-3.—Low water plate. additional  feedwater  treatment  that  might  not otherwise  be  necessary.  Since  the  boiler  and  system arrangements  usually  make  it  impractical  to  perform daily and monthly maintenance of the low water cutoff devices,  it  is  essential  to  remove  the  operating mechanism   from   the   bowl   annually,   or   more frequently if possible, to check and clean the float ball, the internal moving parts, and the bowl housing. Also, check the cross-connecting piping to make certain that it is clean and free of obstructions. GAUGE  GLASS  REPLACEMENT A  broken  or  discolored  gauge  glass  should  be replaced  at  once.  Always  use  new  gaskets  when replacing  a  gauge  glass.  Use  the  proper  size  rubber packing.  Do  not  use  "loose  packing"  that  could  be forced  below  the  glass  and  possibly  plug  the  valve opening. Close the valves when replacing the glass. Slip a packing nut, a packing washer, and a packing ring onto each end of the glass. Insert one end of the glass into the upper gauge valve body far enough to allow the lower end  to  be  dropped  into  the  lower  body.  Slide  the packing nuts onto each valve and tighten. If the glass is replaced while the boiler is in service, open the blowdown valve and slowly bring the glass to operating  temperature  by  cracking  the  gauge  valves slightly.  After  the  glass  is  warmed  up,  close  the blowdown  valve  and  open  the  gauge  valves completely. Check the try cocks and gauge cocks for freedom of operation and clean them as required. It is imperative for the gauge cocks to be mounted in exact alignment. If they are not, the glass will be strained and may  fail  prematurely. FEEDWATER   REGULATOR MAINTENANCE Proper control of the water level requires that the feedwater  regulator  be  maintained.  Here  are  a  few pointers for regulators. If the water level changes from its normal position, make sure you adjust the bypass to manual operation and  check  promptly  for  the  source  failure.  If  leaks develop  around  the  packed  stems,  see  that  they  are stopped immediately. If the boiler is off line, close the hand  valve  in  the  feed  line.  Bear  in  mind  that  the regulator is not designed for use as a stop valve. About once every 3 months, you will probably be called on to assist   in   blowing   down   the   steam   and   water connections  separately. VALVE  MAINTENANCE Valves  deserve  special  care  and  attention  if  they are  to  work  as  intended.  There  may  be  variations among  activities  in  the  type  and  frequency  of  valve inspection  and  servicing  requirements.  Therefore, follow instructions issued by your activity when they differ from those outlined here. Types  of  valves  that  you  may  be  responsible  for helping  service  and  maintain  at  regular  intervals include (1) stop valves of the globe or gate type and (2) stop-and-check valves, which combine in one tray and angle or stop valve of the globe type and a check valve. At least once every 3 months, valves that have not been operated for some time should be operated to prevent sticking. Make sure that you also check for leaks, bent stems,  a  missing  or  broken  handle,  and  lubricate  the exposed threads and gearing of the valve stem. Loosen  and  lift  the  packing  follower  about  once every 3 months or more often if possible. Lubricate the packing with graphite bearing oil or graphite bearing grease.  Replace  the  packing  followers  and  tighten sufficiently to ensure against leaks. BLOWOFF  or  BLOWDOWN  VALVES  should be opened at least once a day. There are four reasons for using these valves: 1. Controlling high water 2. Removing sludge and sediment 3.  Controlling  chemical  concentrations  in  the water 4. Dumping a boiler for cleaning or inspection The  amount  and  frequency  of  blowing  down depends  on  a  chemical  analysis  of  the  water  in  the boiler and operating conditions. On  a  quarterly  basis,  inspect  the  blowoff  valves when  the  boiler  is  washed  out  and  an  internal inspection  is  made.  Check  the  valves  for  leaks,  and inspect   the   pipe   and   fittings   between   the   blowoff 2-3