Category Archives: Line Gun

Line Gun

The goal of using the line gun is to create a taught line across the creek by which to pull the Sontek Hydroboard back and forth to make a discharge measurement. The projectile is fired across the creek from the “shooting side” and retrieved on the “receiving side.” The main line is then attached to the gun’s temporary line and pulled across the creek by staff on the receiving side.  In most instances, the main line is then attached to existing eye bolts using carabiners and other ropes; in other instances, trees, vehicles and other sturdy objects may be used. Below are the steps for pressurizing and firing the line gun.

  1. Use an allen wrench with key cut to make sure the valve on projectile is open (this will allow residual pressure to bleed out of projectile tank and allow pressure from SCBA tank to enter when desired)
  2. Attach yoke to SCBA tank and projectile
  3. Close bleed valves on the SCBA tank side and gun side of the yoke
  4. Open SCBA tank valve and allow pressure to build to 1800 PSI, then close SCBA tank valve
  5. Close projectile tank valve using the allen wrench with key cut, then bleed residual pressure from the lines using bleed valves at each end of the yoke
  6. Removed yoke from SCBA tank and projectile
  7. Pull black line tight, align the projectile and slide the projectile into gun
  8. Attach black line to release pin using carabiner
  9. Unfold stock on line gun
  10. To charge line gun, close valve and check pressure
  11. Release safety (if safety doesn’t release, close valve and bleed off extra pressure)
  12. Fire projectile at approximately 30-degree angle