Category Archives: Field – Other Equipment

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


Load Tester


  1. Test battery voltage without load, as described here
  2. Remove the test leads from the battery and connect the load tester (pictured) alligator clips or hooks to both the red and black test leads
  3. Again, touch the red and black test leads to the proper battery poles
  4. Resistor should warm considerably and voltage should drop from original reading
  5. If the voltage drops less than 0.5 volts and then stabilizes, the battery is good
  6. If the voltage drops rapidly and more than 0.5 volts or fails to stabilize, the battery should be replaced




  1. Turn on the multimeter (volt-ohm meter) and make sure it is set to test direct current, or DC (the V with the solid, not wavy line, next to it), at a range of 20 volts
  2. Touch the red test lead to the red positive (+) pole on the battery and the black test lead to the black negative (-) pole on the battery
  3. Record the voltage displayed on the multimeter
  4. Voltage should be greater than 12.5 volts; if not replace battery

Amp Clamp Meter

  1. Prior to site visit, determine how many amps the solar panel can push
  2. At site, set dial to 40 amps
  3. Toggle button mode to DC
  4. Clamp around black wire (in DC circuits, black is “hot”) and center vertically
  5. Press DC zero button
  6. If taken in full sun, reading should be at or near panel capacity (Ron, are there any hard numbers we could put in here?)
  7. Make sure to return dial to off position


Solar and Battery

Solar Voltage

To test solar voltage (voltage coming directly from solar panel), disconnect one lead from the input terminals and place voltmeter probes on the X’s. Reading should be greater than 14 volts. If not, look for loose connections and damaged solar panel.


Reverse Voltage

To test reverse voltage (voltage passing through the regulator from the battery), disconnect one lead from the input terminals and place voltmeter probes on the X’s. Reading should be less than 0.20 volts (0.50 volts is marginal). If not, replace solar regulator.


Battery Voltage

To test battery voltage, disconnect one lead from the output terminals and place voltmeter probes on the X’s. Reading should be greater than 12.5 volts. If not, replace battery.


Charging Voltage

To test charging voltage (voltage coming through regulator), disconnect one lead from the output terminals and place voltmeter probes on the X’s. If the voltage is greater than 14 volts, replace solar regulator.


 Make sure all leads are reconnected to appropriate terminals when finished.