10 cm survey chamber maintenance

Replacing the gaskets

The 10 cm Survey Chamber uses a series of three gaskets to seal the chamber to the soil collar. The first gasket is a black neoprene "rolled" type gasket that is located on the bottom of the moveable part of the chamber; in most cases this gasket will not need to be replaced unless it is inadvertently damaged. The second gasket (foam seal gasket) rests against the soil collar. It may need to be changed more regularly. The gasket kit is available (part number 8100-622; see Gasket kit).

The foam seal gaskets can become cracked or lose their shape relatively quickly, depending upon the conditions they are used in, and the pressure with which they are placed over the soil collar. Inspect the foam seal gasket before you start making measurements each day; if it appears that it might not form a tight seal against the soil collar, you should replace it.

  • To replace the gaskets:
  1. Remove the 18 Phillips head screws from the metal plate on the bottom of the survey chamber. Set the plate aside.
  2. Caution: Handle the plate carefully and be sure not to bend it.
  3. If you need to replace the foam seal gasket, simply pry it out with a knife or a screwdriver.
  4. Discard the damaged gasket.
  5. Insert the new foam seal gasket by working the gasket with your fingers into the recessed area of the flange.
  6. It may help to work the gasket in with the inside edge first. Press in opposite sides of the gasket to prevent stretching it. Make sure the gasket is seated all the way down into the flange, and that it lays flat without warping.
  7. Align the soil collar gasket holes with the holes in the flange.
  8. There is a top and bottom to the soil collar gasket; if it does not align with the holes on the flange, turn the gasket over and try again.
  9. Insert the screws on opposite sides of the flange, but do not fully tighten until all screws are started.
  10. Partially tighten the screws on opposite sides, and work your way around the ring so that the metal plate lays flat and does not bow.
  11. The screws should not be fully tightened, as this will distort the gasket - tighten until the gasket begins to deform, and then back off slightly.