How to Build a PVC Horn

Build an air horn from PVC.

A PVC horn is an air induction alarm horn for use on a car or other vehicle. Electrical horns work based on an artificial sound, whereas an air horn can produce a louder and shriller alarm because of the high vibration of its rubber membrane. Most PVC air horns are fueled by compressed air, but a well-constructed PVC pipe horn can be activated with only a person's breath. PVC and a rubber balloon are the primary elements in its construction.

Things You'll Need

• Tape measure
• Ruler
• Hacksaw
• 2-inch schedule-80 PVC pipe
• Power drill
• 3/8-inch metal compressed air connection
• PVC adhesive
• Heavy rubber balloon
• Scissors
• 2-inch steel band clamp
• Screwdriver
• Motor oil filler funnel
• Duct tape
• Air compressor
• 5-gallon compressed air tank
• 1/2-inch compressed air touch-valve
• 1/2-inch compressed airline

Instructions

1. Use a tape measure, ruler and marker to mark off an 8-inch piece of PVC pipe. Use a hacksaw to cut the pipe.

2. Drill a 1/2-inch hole in one side of the PVC pipe two inches from one end. Insert the 1/2-inch metal compressed air connector valve, covered with PVC adhesive, into the hole and smear more adhesive round the fitting.

3. Cut a 3-inch circle of heavy rubber balloon material with scissors. Wrap it over the opposite end of the PVC pipe from the air connection end and pull it tight. Slide a 2-inch band clamp around and over the piece of balloon, and pull it down the pipe one-half inch. Tighten the band clamp with a screwdriver.

4. Cut the small end off the oil funnel at about the 1 1/2-inch diameter mark. Note: This is not a precision measurement. Slide the cut end of the funnel into the open end of the PVC pipe until the pipe's inside diameter stops the funnel. Mark the funnel at this point of insertion and cut the remaining, small end of the funnel with a hacksaw. Insert the funnel, small end first, into the open end of the PVC pipe and wrap it securely with duct tape.

5. Attach a 1/2-inch compressed air touch-valve to two pieces of 1/2-inch compressed air line. One section of air line should be five feet in length and the other should reach the air compressor. Attach the short end to the 1/2-inch air valve in the PVC pipe. Attach the other end of the other length of air line to the compressor.

6. Turn on the air compressor and allow it to fill the 5-gallon air tank. When it reaches capacity, touch the air release lever on the touch-valve and the air horn will sound.

Tips & Warnings

• Test the horn with different sized funnels and air pressures.

• Use caution when working with compressed air.

References

• The PVC Project Book: Charles A. Sanders