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[][][]                                                    [][][]
[][][]    A Step by Step Guide to Making a Dry Ice Gun    [][][]
[][][]                                                    [][][]
[][][]                By: The Voice Over                  [][][]
[][][]                                                    [][][]
[][][]         A Metal Communications Presentation        [][][]
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[][]  /\/\etalland 1  10megs/AE/BBS/Cat-Fur [503]538-0761   [][]
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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 puncture 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 until  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:
----------------------

     The  only really  nice modification that  I've discovered is
to replace the pressure chamber pipe  with a "T" joint and  valve
so  as  to  make  a  gun  with  long,  medium,  and  short  range
capability. To do  this, construct the  pressure chamber  section
of the gun like this:

          ___adaptor                                       I
         :  ______________________________________ ________I___
 _____ _ :/!                                      !        I
___#__!o!/ !                                      !        I
        !  !                                      !        I
        !  !        "T" joint                     !        O
________!  !                                      !
:        \ !                                      !
:         \!____________             _____________!___________
:                      !             !                 ^
:                      !_____________!                 !
:__blow gun            !______O______!<-standard       standard
                       !      I      !  valve #2       valve #1
                       !      I      !
                       !      I      !<-short length
                      _!______I______!_  of piping
                      !!             !!
                      +---------------+
           end cap_______/


     What this does is  make a pressure  chamber with a  variable
length.  The following chart shows  the combinations in which the
valves may be used to create different ranges.


 RANGE  !  INSTRUCTIONS
--------+--------------------------------------------------------
 short  ! Open valve number 1, hold it open for about a second,
        ! close it, and then open valve #2.
--------+--------------------------------------------------------
 medium ! Open valve number 1 for about a second and close it.
        ! Leave valve #2 closed.
--------+--------------------------------------------------------
 long   ! Open valve #2 before opening valve #1.  Open valve #1
        ! for about a second, then close it.
--------+--------------------------------------------------------

     The trigger can be squeezed at any time following any of the
above procedures.  Have fun!


This  file may be used  on any system as  long as all credits and
information remain intact.
