Nanometrics TC120-PH1, User Manual

Page: 32 / 90

Chapter 3

Performing a Surface Vault Installation
Trillium Compact User Guide
16889R5

2014-03-04
23
3.7.2 Insulating with a Rigid Foam Box
If you are not using the recommended Trillium Compact Insulating Cover, insulate the
seismometer with a rigid foam box. Use the following recommendations as a guide when
constructing the box:

Construct a five-sided box that is large enough to house the seismometer without
touching the sides of the seismometer or the cable.
Preferably, use rigid foam insulation with foil on one or both sides. There are two
advantages to the foil-coated foam: it has a higher insulation resistance, and you can
make the joints with aluminium tape, which is quicker and cleaner than glue.

Use insulation that is at least 5 cm (2 in.) thick. Depending on the temperature stability
of the site, additional or thicker boxes can be used.

Cut a groove at the appropriate point in the bottom of the box to allow the
seismometer cable to exit.

Seal the box joints properly:
• For rigid foam without a foil coating, glue the joints using polystyrene adhesive or
polyurethane resin, taking care not to leave any gaps.
• For rigid foam with a foil coating, tape the joints with aluminium tape, taking care
not to leave any gaps.

Ensure there is a good seal between the bottom edge of the box and the pier.
Adhesive weatherstripping that is 1.25cm (0.5 in.) thick creates a good seal.

Ensure the thermal insulation box is held firmly in place by setting a weight on top of it.
A brick works well for this purpose.

Strain relieve the cable to the installation surface, close to the seismometer. Tie-wraps
with tie-wrap anchors or a heavy object are effective tools for achieving strain relief.
3.8 Installing a Trillium Compact in the Insulating Cover
Use the following steps to install a Trillium Compact in the Carrying Case / Insulating Cover
for insulating purposes at the installation site:
1. Prepare a flat installation surface.
2. Secure the cable to the side of the seismometer with a tie wrap (see Figure 3-4 “Cut-
away illustration of a Trillium Compact in the insulating cover” on page 24).
3. Use tape or a heavy object to strain relieve the cable on the installation surface.
4. Use your preferred method of aligning and levelling the seismometer (see Section 3.5
“Best Practices for Alignment and Levelling” on page 19).
When installing a Trillium Compact in a rigid foam insulating box, follow the best practices for
aligning and levelling the seismometer that are outlined in
Section 3.5 “Best Practices for
Alignment and Levelling” on page 19.
If you are burying the Trillium Compact and its insulating cover, pull all of the foam out of the
cover. Retain these pieces of foam for future installations and transport. See
Section 3.4
“Alignment, Levelling, and Placement Features” on page 17 for more information on buried
installations.