A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

BACKGROUND OF THE INVENTION 
The invention described herein was made at the Lawrence Livermore 
Laboratory in the course of, or under Contract No. W-7405- ENG-48 between 
the U.S. Energy Research and Development Administration (now the 
Department of Energy) and the University of California. The invention 
relates to vacuum systems, particularly to vacuum system control valves, 
and more particularly to a surge-damping vacuum valve. 
Flow surges are a common ocurrence in vacuum systems. Such flow transients 
are undesirable mainly because they may disturb objects within the vacuum 
system. For example, when a glovebox is being evacuated, the operator must 
open the vacuum valve slowly and cautiously to prevent the initial air 
surge from distrubing materials within the box (sweeping powders out of 
open containers, etc.). Also, for systems requiring a constant vacuum 
pressure, any disruption of that constant pressure creates severe 
problems, thus requiring surge-damping. 
SUMMARY OF THE INVENTION 
The present invention is a vlave having a mechanism for automatically 
damping out flow surges in a vacuum system. Basically, the surge-damping 
mechanism consists of a disk having several slots in its periphery. A 
spring forces the disk to an open position. Upon flow surge the 
differential pressure overcomes the force of the spring and forces the 
disk into sealing engagement with the vacuum port, restricting flow to the 
slots in the rim of the disk, thus damping out the flow surge. When the 
pressure is equalized the spring moves the disk to open position. 
Therefore, it is an object of the invention to provide means for damping 
out flow surges in a vacuum system. 
A further object of the invention is to provide a surge-damping vacuum 
valve. 
Another object of the invention is to provide a vacuum surge damping 
mechanism for a valve utilizing a differential pressure actuated, spring 
loaded, slotted disk which restricts flow under surge conditions. 
Other objects of the invention will become readily apparent to those 
skilled in the art from the following description and accompanying 
drawings.

DETAILED DESCRIPTION OF THE INVENTION 
The invention is directed to a surge-damping mechanism in a vacuum control 
valve for automatically damping out flow surges in a vacuum system. 
FIGS. 1 and 2 illustrate an embodiment of the invention wherein the 
surge-damping mechanism is incorporated in a vacuum control valve 
basically composed of a valve body or housing 2 having a flow control 
piston 4 located in a chamber 6 and controlled by mechanism 8 located 
externally of valve body 2 via a shaft 10. The surge-damping mechanism 
consists of a disk 12 having a rim or flange section 13 with plurality of 
narrow slots 14 on the periphery of the rim or flange section 13, disk 12 
being integral with or secured to a shaft 16 which is movably positioned 
in and supported by a spider 18 (see FIG. 2), with a spring 20 on shaft 16 
which forces disk 12 against tabs or stops 22 on a perforated collar 24 
positioned within a vacuum port 26 of valve body 2. Spider 18 is supported 
within a fitting 28, with fitting 28 having a surface forming a seat 29 
and a groove 30 (see FIG. 2) therein for an O-ring seal 32 and is secured 
to valve body 2 via screws 34. As indicated by legend, fitting 28 is 
adapted to be connected to a vacuum pump, while another fitting 36 secured 
to valve body 2 is adapted to be connected to a system being evacuated as 
indicated by legend. 
FIG. 3 shows the valve surge-damping mechanism underflow surge conditions, 
such as the onset of vacuum pumping. The momentary pressure differential 
across the disk 12 overcomes the force of spring 20 and forces disk 12 
into sealing engagement with seat 29 of fitting 28, thereby restricting 
flow to only through slots 14 in the rim of flange section 13. This 
increased flow resistance damps out the flow surge. When the pressure 
equalizes across disk 12, spring 20 forces disk 12 out of engagement with 
seat 29 of fitting 28 and in contact with tabs or stops 22 of collar 24, 
thereby restoring full flow conductance through the valve as shown in FIG. 
3. 
It has thus been shown that the present invention provides a surge-damping 
mechanism for a vacuum control valve which effectively damps out flow 
surges in a vacuum system, thus overcoming the problems associated with 
flow surges in such a system. 
While a particular embodiment of the invention has been illustrated and 
described, modifications will become apparent to those skilled in the art, 
and it is intended to cover in the appended claims all such modifications 
as come within the spirit and scope of the invention.