The MIT/Harvard Center for Magnetic Resonance plans called for the installation of a 900 MHz Nuclear Magnetic Resonance (NMR) device in its facility. Unfortunately, a very large generator next door produced a narrow-band vibration peak at 28 Hz that exceeded the instrument’s vibration criterion.

Acentech surveyed the floor vibrations to determine ways to reduce vibrations to acceptable levels, considering that potential solutions must accommodate the NMR’s internal vibration system.

We determined that the generator-induced vibrations could be reduced to acceptable levels using high-performance commercial air spring isolators (natural frequencies: 1.5 Hz vertical, 1.2 Hz horizontal). We recommended an 80,000 pound inertia block to dynamically separate the primary isolation system from the NMR isolations, thereby minimizing adverse interactions between the two isolation systems.

The photos show the underside of the block with the air spring isolators and the top surface of the block where the NMR is now located. At the generator’s operating frequency, the system attenuates the floor vibrations by 45 db.