System for accurately weighing solids and control mechanism for same

1. An apparatus for regulating pressure in a closed system, comprising:

a) a compartment partially filled with a liquid so as to define a head space above the liquid;

b) a vacuum port in fluid communication with the head space, so that an environmental pressure of the head space is negative;

c) a vent line for regulating pressure in the head space, the vent line adjustably extending into the liquid;

d) a process line including a first end connected to the closed system, and an opposing second end adjustably extending into the liquid.

2. The apparatus of claim 1 , wherein the apparatus is capable of controlling a pressure level within the closed system to within about 0.125 kPa.

3. The apparatus of claim 1 , wherein the apparatus is capable of controlling a pressure level within the closed system to within about 0.062 kPa.

4. The apparatus of claim 1 , wherein the apparatus is capable of controlling a pressure level within the closed system to within about 0.031 kPa.

5. A closed system, comprising: a) a closed chamber including a gas inlet and a gas outlet; b) an inert gas supply under positive pressure connected to the gas inlet; and c) an apparatus according to claim 1 , wherein the process line first end is connected to the gas outlet.

6. A system, comprising: b) an inert gas supply under positive pressure connected to a gas inlet; and c) a bubbler connected to a gas outlet, the bubbler including a compartment that is partially filled with liquid so as to define a head space, an inlet operatively connected to the gas outlet, a vent, and a vacuum line in fluid communication with the head space so that the head space has a negative pressure.

7. The system of claim 6 , wherein a first dip tube adjustably extends from the inlet to the liquid and into the liquid, and a second dip tube adjustably extends from the vent to the liquid and into the liquid.

8. The system of claim 6 , wherein the bubbler further includes a liquid trap zone disposed between the inlet and the compartment.

9. The system of claim 6 , wherein the bubbler is capable of controlling a pressure level within the closed chamber to within about 0.125 kPa.

10. The system of claim 6 , wherein the bubbler is capable of controlling a pressure level within the closed chamber to within about 0.062 kPa.

11. The system of claim 6 , wherein the bubbler is capable of controlling a pressure level within the closed chamber to within about 0.031 kPa.

12. A process for regulating the pressure in a closed system by use of a regulating device, the device comprising: i) a compartment partially filled with a liquid so as to define a head space above the liquid; ii) a vacuum supply line in fluid communication with the head space; iii) a vent line including an end that adjustably extends into the liquid for regulating pressure within the head space; and second end adjustably extending into the liquid; the process comprising the steps of: a) applying a vacuum to the head space via the vacuum supply line; b) establishing a pressure in the head space by adjusting position of the vent line end disposed in the liquid; and c) establishing a pressure in the closed system by adjusting position of the process line second end disposed in the liquid; wherein the level of vacuum applied to the head space is sufficient to cause bubbles to form at the vent line end disposed in the liquid.

13. The process of claim 12 , wherein the closed system is swept with an inert gas that exits the closed system via the process line.

14. The process of claim 12 , wherein the pressure within the closed system is controlled to within about 0.125 kPa.

15. The process of claim 12 , wherein the pressure within the closed system is controlled to within about 0.062 kPa.

16. The process of claim 12 , wherein the pressure within the closed system is controlled to within about 0.031 kPa.