Page 145 - Gas Adsorption Equilibria

3. Gravimetry 131

Figure 3.5. Magnetic suspension balance (Rubotherm GmbH) for automated gravimetric
measurements of adsorption equilibria of pure corrosive gases. On the r. h. side of
the balance 6 electro-pneumatic valves (Hoke, Frankfurt) for controlling the gas
supply and evacuation of the installation clearly can be recognized.

2.2.2 Theory

To outline the physics of gas adsorption measurements using a magnetic
suspension balance (MSB) let us consider the schematics, Fig. 3.6. It shows
the adsorption chamber filled with sorptive gas at density including the
magnetic suspension consisting mainly of a permanent magnet of mass
below of which a basket filled with sorbent material is
fixed.

If the suspension is floating freely in the sorptive gas atmosphere, the
balance of vertical forces is

Here is the weight of the suspension floating freely in the sorptive gas,
i. e. the vertical force measured by the microbalance, its zero point of
calibration being assumed to refer to the “resting position” of the suspension