
The Infamous...        D R Y   I C E   G U N
                       ---------------------
 Introduction:
 ------------

    In the past,  many people have  experimented with the  power
 generated  by  the  conversion  of dry  ice  into  gaseous carbon
 dioxide. The most  common use  that I have  seen is  the dry  ice
 bomb.  The  dry ice  bomb is  easily  made by  using a  two liter
 plastic bottle,  some hot  water  and some  crushed dry  ice.  To
 make  one, one simply puts about a  cup and a half of crushed dry
 ice into the bottle, adds hot  water, caps the bottle and  throws
 it.  These bombs are  not a joke,  and have been  known to blow a
 metal trash can fifteen  feet into the air,  as well as  bursting
 the  bottom of the can. If you make  a dry ice bomb, you had best
 throw it before it explodes  due to the enormous force  generated
 by  the explosion of  the bottle. A  friend of mine  waited a bit
 too long on  throwing one,  and he  jammed three  of his  fingers
 badly,  got a huge bruise on his  left leg, and one of the plasic
 fragments was propelled with enough force to destroy his  tennis
 shoes  and cut his  foot all to  hell. In short,  be careful with
 these things.

      One day in May of  1985, an idea was  introduced to me by  a
 friend.  His plan was  to control the force  of the expanding dry
 ice and harness it to  a useful end. The  result was the dry  ice
 gun.  In following these plans, please keep in mind that when dry
 ice is finished  expanding, it  can generate pressures  of up  to
 2400  PSI...for this reason, I recommend that when arming the gun
 and when disarming  it, you hold  all valves OPEN,  and that  you
 wear  a pair of protective  goggles at all times.  I will take no
 responsibility for injury that occurs  because of the content  of
 this   file,  or  through  the  use  of  this  information.  This
 information is intended for educational purposes ONLY.

 Materials needed:
 ----------------

      The  materials  required  will vary  for  each  gun produced
 because of the nature of  the construction itself and the  effect
 produced by using different parts.  The following parts, however,
 are necessary for a gun with moderate power and range:

      1- Standard  valve. I  recommend  the kind  that is  just  a
         lever  and turns 1/4  turn to open or  close and has 3/4"
         connectors.

      1- Blow gun (These can be found at auto parts stores... shop
         around  a little  and get  one with  the highest pressure
         rating you can  find (probably  150 PSI)).  This will  be
         sometimes referred to as a valve also.

      1-  Length of hot  water PVC piping...this  will be used for
         the  barrel.  I  recommend  that  you  use  3/4"  piping,
         because  that is the kind that  fits paint pellets of the
         type used  in  KILLER best.  Note,  however, that  it  is
         possible to launch anything up to the size of an egg with
         pleasing results,  provided  that  the  barrel  is  large
         enough in diameter.

      You  will also need various lengths of regular lead or steel
 piping (to construct  the actual  gun), and adapters  to get  the
 blow  gun to  fit the  rest of  the gun  (blow guns  usually have
 connectors that are 1/4" in diameter,  while the rest of the  gun
 (except  the dry ice  container) should be  constructed with 3/4"
 fittings). You will  also need an  end cap  to go on  the end  of
 your dry ice container and probably an elbow joint.

 Optional parts:
 --------------

      1- Standard valve (same  kind as above,  but with a  shorter
         lever).

      1- "T" joint with 3/4" connectors all around.

      1- 6 or 7 inch length of 3/4" diameter pipe.

      1- 3/4" end cap.

      Form-a-gasket and pipe dope

 Construction:
 ------------

      Because of the  nature of  the gun,  step-by-step plans  are
 not  possible. However,  a diagram  of the  gun will  give you an
 idea of what has to be  done, and construction tips should  prove
 enough to allow successful completion of the project.

 Diagram:
 -------

    trigger (part of the blow gun)   standard
    adaptor______________        :    valve
                         \       :        \
                          :      :         :
   ______________________ :    _ ;    _____:______
  !                      !\__ __!__________________________________ /!      !
  \
  !  barrel              ! __!__!__! !   O  !      \
  !______________________!/  joint B____________/  :  :  :    I     \     \
        blow gun_____________/   :  :    I    / \     \
        pressure chamber________/   :    I   /  !_____!<-joint A
        adaptor____________________/        /   !     !
        elbow joint________________________/   /!     !
        dry ice container_____________________/ !     !
        end cap_______________________________ _!_____!_
                                              \!!     !!
                                               +-------+


 NOTES:

      1-  The dry ice container can be any size...the one I use is
         about 6 inches long by  2 inches in diameter. The  larger
         the  chamber is, the more shots  the gun will fire before
         reloading is necessary.

      2- The elbow joint can be  left out...it will only make  the
         gun  in  the  shape  of  a  straight  rod  rather  than a
         "traditional" gun shape.

      3- The barrel length  can be any length  you like, but  very
         long  ones are cumbersome and very short ones don't allow
         much accuracy. I recommend a length  of about 2 1/2 to  3
         feet.

      4-  all joints except  the two marked 'A'  and 'B' should be
         tightened as much as possible  and sealed by coating  the
         threads  with the form-a-gasket and  then putting the two
         pieces together and tightening them as much as  possible.
         If  you like, you can also  caulk around the finished and
         tightened joint.

      5- The joint marked 'B' should be tight, but DO NOT SEAL  IT
         unless  you do not intend to  ever use more than one kind
         of barrel.

      6- The joint marked  'A' should not  be sealed with  form-a-
         gasket  like the  others because it  is the  one that you
         will be  filling the  dry ice  into the  gun through.  To
         fill  the gun  with dry ice,  detach the  dry ice chamber
         pipe from the  elbow joint.  Load the  container with  as
         much  crushed dry  ice as  it will  hold. Then,  coat the
         threads of  one of  the  pieces of  the joint  with  pipe
         dope.  This will  prevent leakage  of the  carbon dioxide
         after it has changed into gaseous form.

      7- The  pressure chamber  should be  about 1  1/2 inches  in
         length   for  a  fairly  powerful  gun.  The  longer  the
         pressure chamber  is,  the  more  powerful  the  gun.  On
         a  gun  with a  three inch  pressure  chamber, we  shot a
         AA battery  500  (yes,  hundred) feet  across  a  parking
         lot.  Such  high  power, however,  is  dangerous,  and is
         not recommended  for use  in games  such as  Killer,  but
         rather for target practice (on INANIMATE objects).

 How to operate the dry ice gun:
 ------------------------------

      Once you have the  dry ice gun built  and loaded, the  first
 thing  you must do is to open  the standard valve and immerse the
 gun in  water. This  is to  check  for leaks.  If any  leaks  are
 present,  they will show up as streams of bubbles rising from the
 gun. If any are  found, tighten the offending  joint and put  the
 gun  back in  the water. When  all leaks are  gone (if necessary,
 take the  whole  thing  apart  and rebuild  it  from  scratch  to
 eliminate  leaks,  especially  on  either  end  of  the  pressure
 chamber), release the  pressure built  up so far  by closing  the
 standard  valve and then  operating the trigger.  You should hear
 a  'woosh'  sound,  and  the  gun  should  kick  slightly.   This
 indicates that all is working properly.  When loading the dry ice
 gun, it is important to keep  both valves OPEN until the dry  ice
 container  is secure, and then close  both valves. Even after you
 are sure  that the  gun has  no  leaks anywhere,  it is  good  to
 immerse  the dry ice container (while  it is attached to the gun)
 in water. This  warms the dry  ice and causes  it to change  into
 gaseous carbon dioxide.

      After  the dry ice container has been immersed for 5 minutes
 or so, remove the gun from the  water and dry it off. The gun  is
 now ready to be fired.

 Firing the dry ice gun:
 ----------------------

      This is the  simplest step of  all. To fire  the gun  simply
 place  the projectile (I  recommend paint pellets)  in the barrel
 of the  gun, open  the  standard valve  for  about a  second  and
 then  close it.  You should  hear a muffled  rush of  air as some
 of the gaseous  CO2 is bled  into the pressure  chamber. Aim  the
 gun  at who/whatever  you wish to  hit, and  squeeze the trigger.
 For more power, you can leave the standard valve open and squeeze
 the trigger.

 Disarming the dry ice gun:
 -------------------------

      To disarm the gun, open both valves until you can no  longer
 hear  the pressure escaping through the  barrel of the gun. Then,
 unscrew the dry  ice container  and place  it in  cold water  for
 about  3 to 4 minutes, or untol  all of the remaining dry ice has
 evaporated. When all of the dry ice is gone, clean the threads on
 the  dry ice container  and elbow joint,  and store the  gun in a
 clean, dry area.

 Suggested modifcations:
 ----------------------