15
Auto zero pressure:
Zeros the pressure sensor before the test start, taking away any
ambient pressure changes, which may affect the test. The pre-set limits are -68 to +68. If
the instrument starts failing during this process, there may be a fault in the system, which
requires checking.
Auto zero left force sensor:
Tares the left force sensor, which removes the effect of any
minor changes in pack weight or infill variances. The pre-set limits are -99 to 9999. if the
instrument starts failing during this process, there may be a fault in the system, which
requires checking.
Auto zero right force sensor:
Described in “Auto zero left force sensor”.
Fill:
Evacuates the chamber of air to a controlled pre-set limit; allows the positive
pressure inside the pack to inflate the pack, creating the force onto the load cell,
and a pressure differential between the inside of the pack and its outside. The
lower the pre-set pressure, the greater pressure differential is inside and outside the
pack. Depending on the pack’s construction, a large pressure difference can cause
the pack to burst/split/open.
Fill 2 left gross:
Measures the force applied to the load cell to ensure it’s
sufficient. A pack with a large hole or altogether missing will not inflate to create a
force, or inflate enough to create force to reach the minimum limit of the test. The
limit is determined by knowledge the normal force created by a known good pack
onto the load cell, and then setting the limit (gross) below the lowest recorded
known good pack. Creating a pack with a known gross leak can test to confirm the
parameters are set.
Fill 3 right gross
: Described for “fill 3 left gross”.
Isolate
: A half-second step to allow time for valves to operate before proceeding.
Stabilize:
Allows the pack to settle into its inflated position. The packs don’t
inflate uniformly. While the pack is stabilizing, the force on the load cell will vary as it
settles into the inflated shape. If the stabilization step is too short, it could lead to false
failures of good packs.
Stabilize measure left force:
Once the stabilization period is over, the force on the
load cell is measured to ensure the force has been maintained during the
stabilization step. A pack with a hole smaller than a gross but greater than a fine
leak, could drop below the gross limit during stabilization, therefore, if after
stabilization the force is not great enough, then the pack will be read as a reject.
The limit should be the same as the gross leak test (fill step measure).
