Figure 4-15.—TODD LVS atomizer. Figure 4-17.—Vented-plunger atomizer. We  will  describe  the  more  common  method— lighting  fires  with  a  torch. Figure  4-16.—Y-Jet  steam  atomizer. Steam-Assist Atomizer.— The steam-assist atomizer  employs  150  psi  of  steam  mixed  with  the fuel oil to help atomize the fuel oil. The two most common steam-assist atomizers in use by the Navy are  the  TODD  LVS  (fig.  4-15)  and  the  Y-Jet (fig. 4-16). All steam-assist atomizers must have low-pressure  air  hookup  for  use  as  a  substitute when suitable auxiliary steam is not available. Vented-Plunger  Atomizer.—  The  vented- plunger atomizer shown in figure 4-17 is unique in that it is the only atomizer in use in the Navy that  has  moving  parts.  The  fuel  oil  flows  down the  atomizer  barrel  and  around  the  atomizer cartridge. The pressure in the barrel forces the fuel oil into the cartridge through the holes drilled in the   cartridge.   As   the   fuel   is   forced   into   the cartridge,  it  begins  to  spin.  This  motion  forces  the fuel  out  through  the  orifice  in  a  fine  mist. Increasing  fuel-oil  pressure  in  the  atomizer barrel  and  cartridge  will  cause  the  piston  to overcome the spring pressure. The piston is then forced back, uncovering more holes and allowing fuel to be atomized and forced into the furnace. As  pressure  decreases,  the  opposite  occurs.  The spring tension recalls the piston, covering the holes and  allowing  less  fuel  oil  to  be  atomized. Fire In most boilers, a torch is used to light fires. However,  some  boilers  may  have  electric  igniters. Boiler  light  off  is  always  a  two-person operation.   One   person   is   needed   to   handle the   torch,   the   air   register,   and   the   furnace, and  the  other  to  open  the  fuel-oil  root  valve.  If fires  do  not  light  in  2  or  3  seconds,  you  must secure the fuel oil and investigate the reason for the  failure  to  light.  The  boiler  furnace  must  be inspected and repurged before the next attempt to light. The   basic   light-off   procedure   involves   the following  steps: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Ensure  that  all  fuel-oil  manifold  and atomizer/safety  shut-off  valves  are  shut. Insert a clean atomizer with a lighting- off sprayer plate into the No. 1 burner. Adjust  the  combustion  air  and  fuel-oil pressures for lighting the fires. Ignite  the  lighting-off  torch. Insert the lighted torch into the lighting- off  port  and  close  the  port  cover;  visually check to ensure that the torch remains lighted.  However,  you  should  never insert a torch into a furnace until you are sure that no fuel is on the furnace deck and that the boiler has been purged of all  combustible  gases. Open the No. 1 burner fuel-oil atomizer/ safety  shut-off  valve(s). Open  the  No.  1  burner  fuel-oil  supply manifold  valve  one-half  turn. Observe the furnace through the No. 1 burner observation port to ensure that the ignition is successful. Adjust  the  flame  with  the  burner  air register  handle. Open  the  No.  1  burner  fuel-oil  supply manifold  to  the  fully  open  position. Withdraw  and  extinguish  the  torch. 4-14