l The digitizer cable must be flexible enough to bend without applying significant forces
to the seismometer. Nanometrics provides ultra-flexible cables designed for this
purpose. See "Cables and Accessories" on page12.
l The insulation surrounding the seismometer must:
l Have low thermal conductivity to insulate the seismometer from temperature
changes.
l Form a nearly airtight seal against the pier to block drafts.
l Fit closely around the seismometer, eliminating space that may cause convection
inside the cover.
l Not touch the seismometer or the cable. The insulation is subject to temperature
expansion and can exert measurable forces on the seismometer.
3.9 Insulation Options
There are two options for insulating a Trillium Compact Vault:
l Recommended method. Use the Nanometrics Trillium Compact Carrying Case/
(Nanometrics part number 16862). See also "Insulating a Trillium Compact Vault with
the Insulating Cover" below.
l Make a freestanding cover using rigid foam insulation that is sealed against air drafts,
does not touch the seismometer, and minimizes the volume of air trapped between the
insulating box and the seismometer. See also "Insulating a Trillium Compact Vault with a
Rigid Foam Box" on page45.
Before proceeding with the implementation of thermal insulation, there are many aspects you
must consider in the context of the particular site and type of installation. See "Preparing the
Site for a Vault Installation" on page32.
3.9.1 Insulating a Trillium Compact Vault with the Insulating Cover
Nanometrics recommends insulating your Trillium Compact seismometer with its specially
designed Carrying Case / Insulating Cover, which, when properly installed, will attenuate
temperature-induced long-period noise.
Chapter 3 - Installing a Trillium Compact Vault Seismometer
16889R10 • 2020-11-12 Page 42
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