Do  not  alter  or  deface  the  numbers  or  other markings  on  the  cylinders.  Do  not  add  markings without approval of the engineer officer. Do not issue  cylinders  if  their  contents  cannot  be identified. Detailed information relative to the stowage, handling, and  use  of  various  types  of  compressed  gases  are contained  in  the  Naval  Ships’  Technical  Manual. Information pertinent to especially hazardous gases commonly  used  by  ships  is  as  follows. ACETYLENE.— Acetylene is inherently unstable,  and  may  explode  when  subjected  to  heat  or shock  or  upon  contact  with  chlorine  or  certain  metals such   as   copper,   silver,   and   mercury.   Therefore, acetylene must be stowed separately from oxygen or any other materials with which it forms an explosive compound. The gas must never be allowed to escape into  an  enclosed  area  The  cylinders  must  be  protected from flames, sparks, lightning, and static electricity. Testing for suspected leaks should be done with soapy water. Toxicity.— In  moderate  concentrations,  acetylene may  act  as  an  intoxicant.  In  higher  concentrations,  it will   cause   unconsciousness   and   ultimately asphyxiation. Some grades of acetylene also contain many  impurities.  Therefore,  breathing  of  acetylene  in any  concentration  for  any  length  of  time  must  be avoided. Upright  Stowage  Required.—  Acetylene   in cylinders is dissolved in acetone which has a tendency to  flow  into  the  valve  if  the  cylinders  a  stowed horizontally. For this reason, acetylene must be stowed and used only in an upright position with the valve end up.  When  it  is  known  or  suspected  that  acetylene cylinders  have  been  stowed  on  their  sides,  they  will  not be used until they have been in a vertical position for at least 2 hours. OXYGEN   AND   CHLORINE.—   Oxygen   and chlorine  are  oxidizing  gases  that  strongly  support combustion. Chlorine is also poisonous. Oxygen and chlorine  cylinders  must  be  stowed  on  the  weather  deck, or in a separate watertight storeroom which has at least one compartment between it and any space that is used for the stowage of combustibles such as flammable liquids or gases, ammunition, paint, gasoline, and oil. NONFLAMMABLE GASES.— Helium, nitrogen, carbon dioxide, and argon arem nonflammable gases. Because of their inert characteristics, they may be stowed with flammable or oxidizing gases. Since these non-flammable gases will not support expiration (a sufficient concentration in a closed space will cause asphyxiation),  they  must  bestowed  on  the  weather  deck or  in  other  well-ventilated  spaces. AEROSOL PRO DUCTS.— Aerosol  products  are liquids,  solutions,  or  powders  suspended  in  a  gas propellant  and  contained  in  dispensers  equipped  with release  valves.  Aerosol  containers  are  used  for  the dispersal  of  paints,  enamels,  lacquers,  insecticides, silicones  rust  preventives,  etc.  The  aerosol  propellants may be low boiling halogenated hydrocarbons or other hydrocarbons  such  as  liquified  propane  or  isobutane. Aerosol  cylinders  will  burst  if  exposed  to  heat  sources in  excess  of  120  degrees  F.  They  are  prone  to  leakage if  subjected  to  impact.  Aerosol  propellants  are extremely  flammable  and  in  sufficient  concentration, can be anesthetic or asphyxiating. Aerosol products should  be  stowed  in  the  flammable  liquids  storeroom, or   in   cabinets   away   from   oxidizing   materials. Mechanical  ventilation  will  be  used,  when  necessary,  to remove  accumulated  vapors. Flammable or Combustible Material Flammable liquids have a flash point of 100 degrees F or below. Combustible liquids, greases, and pastes have a flash point of 200 degrees For below. Items which are flammable and/or combustible include: gasoline,  oils  kerosene,  and  other  petroleum products;  chemicals;    stencil paints, marking inks, and printer’s ink; solvents,   thinners,   primers,   compounds, varnishes and lacquers; alcohol, acetone, ether, and naphtha; greases  and  pastes. Except  for  drummed  petroleum  products,  which  may  be stowed in racks on the weather deck in accordance with the Naval Ships’ Technical Manual, flammable liquids and  other  flammable  or  combustible  material  will  be stowed in the flammable liquids storeroom. Radioactive  Material Radioactive items listed in the MLN are identified by  special  material  content  code  “R”  (or  “X”  if radioactive and magnetic). Radioactive instruments, electron tubes, and certain other items are labeled with the conventional United States Nuclear Regulatory Commission  (USNRC)  radiation  symbol.  This  symbol must NOT be removed or obliterated. The radiation levels of radioactive material depend upon the type and 6-12