| 摘要 |
<p>The closed expansion vessel is for a central heating system, being connected via a pump, valve and pressure swith to the system circuit. Dependent on variations in volume of the liquid in the circuit, liquid is delivered by the pump into the latter from the vessel, or allowed to flow back into the vessel again, the vessel being partly filled with a gas cushion. The pressure of the cushion is set to a low level, even a vacuum, in relation to the lowest pressure in the circuit, which at all times is above atmospheric. The cushion is in direct contact with the surface of the liquid.</p> |
