Popup Sprinkler - Halloween Props

07/01/2000

Pistons driven by compressed air  can be used to automate all sorts of props. Some examples include the infamous "Trash Can Trauma" by Carl  Chetta.

Included on this page are some some ideas on pistons, some of  which have been used by myself. One of the easiest pistons to utilize is an  extended popup sprinkler head. The following text and diagrams demonstrate using  a popup sprinkler head as a piston triggered by compressed air.
 

Picture in Figure 1-1 is a popup  sprinkler head. The sprinkler head is in the retracted (normal) position. Inside  the base of the sprinkler head is a spring that allows the retraction to  occur.

When air is forced up through the  bottom of the base, the piston is extended as seen in Figure 1-2. Of course, the  top of the sprinkler head must be "capped" in order for the piston action to be  triggered. Each end of the unit has male threaded 1/2" connectors. PVC or CPVC  connectors can be used to make the terminations and connections to your  compressed air supply.

Figure 1-3 shows the top of the  sprinkler head being terminated with a piece of CPVC pipe. The bottom is a  female connection glued to a piece of 1/2" CPVC pipe. An end cap is glued to the  top of the pipe. A small hole is drilled at the bottom of the pipe to allow for  air to escape after pressure is released. The extension pipe can be of any  length needed to fit your needs. The extension, however, will always be part of  the piston that is not retracted fully into the base of the unit. The piston is  also limited to the length of the original unit. In this case, 12  inches.

The pictures on the left  show how I attached the sprinkler head to the garbage can. I drilled two small  holes in the back of the trash can, one on each side of where I wanted to mount  the sprinkler head. In my case, I wanted to mount the head in the middle back. I  then took a plastic fastener, the fancy garbage bag type found in the electric  section of the hardware store, and fastened the head to the garbage can by  pulling the fastener tight. I then drilled two more holes below the ones I just  made and added a second fastener.

The CPVC pipe that feeds the sprinkler  head is simply feed through the back of the garbage can