U.S. patent application number 10/758968 was filed with the patent office on 2005-01-06 for combination manual/pneumatic shut-off valve.
Invention is credited to Barros, Philip, Crockett, Mark Adam, Martin, Raul A., Mohammed, Balarabe Nuhu, Sklar, Eric S..
Application Number | 20050000570 10/758968 |
Document ID | / |
Family ID | 34619247 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050000570 |
Kind Code |
A1 |
Mohammed, Balarabe Nuhu ; et
al. |
January 6, 2005 |
Combination manual/pneumatic shut-off valve
Abstract
A combination manual/pneumatic shut-off valve (11) is disclosed.
The valve comprises a housing (13); a valve chamber (17) which is
disposed in the housing and which has a fluid inlet (19) and a
fluid outlet (21); a diaphragm (23); a valve seat (25); a
pneumatically driven actuator (29) which is adapted to move the
diaphragm from a first position in which the diaphragm and the
valve seat form a seal between the fluid inlet and the fluid
outlet, to a second position in which the fluid inlet and fluid
outlet are in open communication with each other; and a handle (31)
adapted to manually move the diaphragm from the second position to
the first position by way of the actuator, independently of the
pneumatic control signal. The valve allows the length of process
fluid control assemblies, and hence the size of fluid panels, to be
reduced by combining the functionalities of a manual valve and a
pneumatic valve into a single element.
Inventors: |
Mohammed, Balarabe Nuhu;
(Union City, CA) ; Barros, Philip; (San Jose,
CA) ; Martin, Raul A.; (Walnut Creek, CA) ;
Crockett, Mark Adam; (Cupertino, CA) ; Sklar, Eric
S.; (Santa Clara, CA) |
Correspondence
Address: |
Patent Counsel, M/S 2061
Legal Affairs Department
Applied Materials, Inc.
P.O. Box 450A
Santa Clara
CA
95052
US
|
Family ID: |
34619247 |
Appl. No.: |
10/758968 |
Filed: |
January 16, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60440928 |
Jan 17, 2003 |
|
|
|
Current U.S.
Class: |
137/487.5 ;
251/14 |
Current CPC
Class: |
Y10T 137/87169 20150401;
Y10T 137/0379 20150401; Y10T 137/87885 20150401; F16K 27/003
20130101; F16K 31/143 20130101; Y10T 137/87917 20150401; G05D
7/0635 20130101; F16K 7/17 20130101; Y10T 137/86662 20150401; Y10T
137/7761 20150401; Y10T 137/87877 20150401 |
Class at
Publication: |
137/487.5 ;
251/014 |
International
Class: |
G05D 007/06; F16K
031/143 |
Claims
1. A pressure-compensating mass flow controller, said mass flow
controller comprising: a control valve; a flow sensor; and a
pressure sensor positioned upstream from said control valve,
wherein said control valve is operated based on signals from said
flow sensor and from said pressure sensor.
2. The pressure-compensating mass flow controller of claim 1,
wherein said flow sensor is positioned upstream from said control
valve.
3. The pressure-compensating mass flow controller of claim 2,
wherein said pressure sensor is positioned upstream of said flow
sensor.
4. The pressure-compensating mass flow controller of claim 1,
wherein said mass flow controller further comprises a filter.
5. The pressure-compensating mass flow controller of claim 4,
wherein said filter is positioned upstream of said pressure sensor,
said flow sensor and said control valve.
6. The pressure-compensating mass flow controller of claim 1,
wherein said flow sensor is a thermal flow sensor.
7. The pressure-compensating mass flow controller of claim 1,
wherein said mass flow controller comprises a display, said display
displaying data based on said signal from said pressure sensor.
8. A process fluid control assembly comprising a
pressure-compensating mass flow controller in accordance with claim
1; and a first pneumatic valve positioned upstream of said
pressure-compensating mass flow controller, said first pneumatic
valve being adapted to control the flow of a fluid through the
process fluid control assembly in response to a first pneumatic
signal.
9. The process fluid control assembly of claim 8, comprising a
manual shutoff valve upstream of said pressure-compensating mass
flow controller.
10. The process fluid control assembly of claim 8, wherein said
first pneumatic valve comprises a handle adapted for manual
shutoff.
11. The process fluid control assembly of claim 8, wherein said
first pneumatic valve comprises an actuator and a handle, wherein
said actuator is adapted to move the valve, in response to a
pneumatic signal, from a closed state into an open state, and
wherein said handle is adapted to move said valve from said open
state into said closed state regardless of whether a pneumatic
signal is present.
12. The process fluid control assembly of claim 8, comprising a
second pneumatic valve upstream of said pressure-compensating mass
flow controller and a third pneumatic valve downstream of said
pressure-compensating mass flow controller, said second and third
pneumatic valves being adapted to control the flow of a fluid
through the process fluid control assembly in response to second
and third pneumatic signals.
13. The process fluid control assembly of claim 8, wherein said
assembly does not comprise a pressure regulator.
14. A fluid control panel, comprising: a substrate; and a plurality
of process fluid control assemblies in accordance with claim 8
disposed on said substrate.
15. A combination manual/pneumatic valve for a fluid control
assembly, the valve comprising: a housing; a valve chamber disposed
in said housing, said valve chamber having a fluid inlet and a
fluid outlet; a pneumatically driven actuator adapted to move the
valve, in response to a pneumatic signal, between a first state in
which the flow of fluid between the fluid inlet and the fluid
outlet is stopped, and a second state in which flow of fluid
between the fluid inlet and the fluid outlet is permitted; and a
handle adapted to move said valve from the second state into the
first state, regardless of whether a pneumatic signal is present at
the actuator.
16. The valve of claim 15, wherein said handle is movable between a
first position and a second position, and wherein said actuator is
adapted to move said valve from the first state to the second state
only when the handle is not in the second position.
17. The valve of claim 15, further comprising a diaphragm and a
valve seat, and wherein the diaphragm is pressed against the valve
seat when the valve is in said first state, thereby preventing the
flow of fluid between the fluid inlet and fluid outlet.
18. The valve of claim 17, further comprising an expansion chamber
having a piston therein which is adapted to press the diaphragm
against the valve seat when no pneumatic signal is present at said
actuator.
19. The valve of claim 18, wherein said housing is equipped with an
air inlet adapted to receive a pneumatic signal, and an air outlet
adapted to bring said expansion chamber to atmospheric pressure
when said air outlet is brought into open communication with said
expansion chamber.
20. The valve of claim 19, wherein said handle is movable between a
first position and a second position, and wherein the piston is
adapted such that the presence of a pneumatic signal withdraws the
piston from the diaphragm only when the handle is not in the second
position.
21. The valve of claim 20, wherein said air outlet is in open
communication with said expansion chamber when the handle is in
said second position.
22. The valve of claim 21, wherein said piston allows the diaphragm
to move from a position in which it is pressed against the valve
seat, to a different position, by advancing along a longitudinal
axis in a first direction in response to a pneumatic signal.
23. The valve of claim 17, further comprising a spring adapted to
maintain a compressive force on said diaphragm.
24. The valve of claim 15, wherein said handle is equipped with a
threaded cylinder that rotatingly engages a complementarily
threaded aperture in said housing.
25. The valve of claim 24, wherein said housing is equipped with an
inlet adapted to introduce pressurized air into said expansion
chamber, and an outlet adapted to exhaust said expansion
chamber.
26. The valve of claim 25, wherein said handle has a shaft that is
equipped with a passageway defined by first and second apertures
that are in open communication with each other, and wherein said
first aperture is in open communication with said expansion
chamber.
27. The valve of claim 26, wherein said second aperture is
adjustable, by rotation of said handle, from a first position in
which it is in open communication with said inlet, to a second
position in which it is in open communication with said outlet.
Description
STATEMENT OF RELATED APPLICATION
[0001] This application claims the benefit of priority to U.S.
Provisional Patent Application 60/440,928, filed Jan. 17, 2003, and
entitled "Combination Manual/Pneumatic Shut-Off Valve."
FIELD OF THE INVENTION
[0002] The present invention relates to process fluid control
assemblies, and more particularly to shut-off valves for process
fluid control assemblies.
BACKGROUND OF THE INVENTION
[0003] Almost every process step during semiconductor wafer
processing that adds, alters or removes material on silicon wafers
utilizes one or more process fluids. These process fluids range
from inert fluids, such as helium, to toxic and corrosive fluids,
such as chlorine. Consequently, semiconductor wafer processing
requires sophisticated fluid delivery systems that can delivery a
variety of process fluids in precise amounts to a wafer processing
chamber.
[0004] In a typical processing assembly, the process fluids are
contained in individual pressurized cylinders that are under the
control of a facility system external to the processing equipment.
The fluids are then supplied to the equipment through tubing, and a
fluid panel controls the flow of fluid from the point of connection
to that tubing to the process chamber. The fluid panel is commonly
divided into individual process fluid control assemblies, each of
which is a complete assembly of components (such as valves,
filters, fluid purifiers, pressure regulators, and transducers) for
one fluid stream.
[0005] FIG. 1 shows a process fluid control assembly 101
configuration in a typical prior art fluid panel. The configuration
shown is of the type commonly used for toxic fluids, such as
chlorine. The process fluid control assembly comprises a manual
diaphragm valve 103 that serves as a safety device by allowing the
flow of fluid through the assembly to be manually turned off for
maintenance and service. Fluid pressure is controlled by a pressure
regulator 105 and a pressure transducer 107. A filter 109 is
provided to remove impurities from the fluid stream. First 111 and
second 113 pneumatic valves operate to allow the flow of fluid to
be remotely turned on and off by sending an electronic signal to
both pneumatic valves and to the mass flow controller (MFC) 115,
the latter of which provides precision control of fluid flow
through the process fluid control assembly. Third 117 and fourth
119 pneumatic valves are provided so that the mass flow controller
can be purged for maintenance. (The third and fourth pneumatic
valves are typically not present in process fluid control
assemblies of this type which are designed for use with inert
fluids.) A communication port 121 is provided on the mass flow
controller to allow it to be accessed and controlled remotely.
[0006] While the process fluid control assembly configuration of
FIG. 1 allows the fluid panel to provide good control over fluid
delivery to the wafer processing chamber, the number of components
in this configuration causes the fluid panel to be exceedingly
bulky and complex. This is especially so for wafer processing
chambers that require several different process fluids.
[0007] There is thus a need in the art for process fluid control
assembly and fluid panel configurations that are more compact
and/or have fewer components, without sacrificing functionality,
ease of serviceability and modularity of the configuration. These
and other needs are met by the devices and methodologies disclosed
herein.
SUMMARY OF THE INVENTION
[0008] In one aspect, a device is provided which comprises an
actuator and a handle. The actuator is adapted to move the device,
in response to a pneumatic signal, from a first state (which may be
a closed state) into a second state (which may be an open state),
and the handle is adapted to move the device from the second state
into the first state regardless of whether a pneumatic signal is
present. The device may be, for example, a fluid control assembly
equipped with a valve, wherein the valve is closed in the first
state and is open in the second state, or it may be a pneumatically
driven latch, wherein the latch is closed in the first state and is
open in the second state. The handle is typically manually driven,
as by rotating it about an axis, and the actuator is typically
pneumatically driven. The device may comprise a diaphragm and a
valve seat, and the actuator may be adapted to move the device, in
response to a pneumatic signal, from a first state in which the
diaphragm is pressed against the valve seat, to a second state in
which the diaphragm is not pressed against the valve seat. The
device may further comprise a valve chamber having a fluid inlet
and a fluid outlet, wherein the diaphragm and the valve seat form a
seal between the fluid inlet and the fluid outlet. In such
embodiments, the fluid inlet and the fluid outlet will typically be
in open communication with each other when the device is in the
second state.
[0009] In another aspect, a combination manual/pneumatic valve for
a process fluid control assembly is provided. The valve comprises
(a) a housing, (b) a valve chamber disposed in the housing which
has a fluid inlet and a fluid outlet and which may also contain a
diaphragm and a valve seat, (c) a pneumatically driven actuator
which is adapted to move the valve, in response to a pneumatic
signal, from a first state in which the flow of fluid between the
fluid inlet and the fluid outlet is stopped, into a second state in
which flow of fluid between the fluid inlet and the fluid outlet is
permitted; and (d) a handle adapted to move the valve from the
second state into the first state, regardless of whether a
pneumatic signal is present at the actuator. When the valve is in
the first state, the diaphragm and the valve seat typically form a
seal between the fluid inlet and the fluid outlet; conversely, when
the valve is in the second state, the fluid inlet and the fluid
outlet are typically in open communication with each other. The
valve may further comprise an expansion chamber having a piston
therein which is adapted to move the diaphragm from a position in
which it is pressed against the valve seat to a different position
in response to a signal, as, for example, by advancing along a
longitudinal axis in a first direction, and the expansion chamber
may be equipped with an inlet adapted to introduce pressurized air
into the expansion chamber, and an outlet adapted to exhaust the
expansion chamber. The valve may also comprise a spring adapted to
maintain a compressive force on the diaphragm.
[0010] The handle of the valve may be equipped with a threaded
cylinder that rotatingly engages a complementarily threaded
aperture in the housing, thereby moving the valve into the first
state. The handle of the valve may have a shaft that is equipped
with a passageway defined by first and second apertures that are in
open communication with each other, and wherein the first aperture
is in open communication with the expansion chamber. The second
aperture may be adjustable, by rotation of the handle, from a first
position in which it is in open communication with the inlet, to a
second position in which it is in open communication with the
outlet. The valve seat may be an o-ring and may be disposed about
the fluid inlet such that the actuator compresses the diaphragm
against the o-ring when the valve is in the first state.
[0011] In some configurations, the valve is adapted such that a
spring holds the diaphragm against the valve seat when the valve is
in the first state and the pneumatic chamber and piston counteract
the spring to allow the diaphragm to move so that the valve can
enter the second state. The disconnection of the pneumatic chamber
from the inlet and the connection of the pneumatic chamber to the
outlet (accomplished by the single act of rotating the handle),
places the valve in a closed position and disables the pneumatic
control. Such a configuration may also include a mechanical linkage
such that the rotation of the handle causes axial force to be
applied to the diaphragm, holding it against the seat with a force
in addition to that provided by the spring.
[0012] In still another aspect, a process fluid control assembly is
provided herein which comprises first and second pneumatic valves,
a mass flow controller, and a combination manual/pneumatic valve,
wherein the first pneumatic valve is upstream from the mass flow
controller, wherein the second pneumatic valve is downstream from
the mass flow controller, and wherein the combination valve is
upstream from the first pneumatic valve.
[0013] In yet another aspect, a fluid panel is provided herein
which comprises a substrate, and a plurality of process fluid
control assemblies disposed on said substrate. Each of the
plurality of process fluid control assemblies comprises first and
second pneumatic valves, a mass flow controller, and a combination
manual/pneumatic valve. The first pneumatic valve is upstream from
the mass flow controller, the second pneumatic valve is downstream
from the mass flow controller, and the combination valve is
upstream from said first pneumatic valve.
[0014] These and other aspects are described in greater detail
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic illustration of a prior art process
fluid control assembly;
[0016] FIG. 2 is a schematic illustration of a combination
valve/manual handle (shown in a manually enabled, pneumatically
closed position) in accordance with the teachings herein;
[0017] FIG. 3 is a schematic illustration of a combination
valve/manual handle (shown in a manually enabled, pneumatically
open position) in accordance with the teachings herein;
[0018] FIG. 4 is a schematic illustration of a combination
valve/manual handle (shown in a manually disabled valve with a
pneumatic signal to open the valve being provided, but with the
valve closed) in accordance with the teachings herein;
[0019] FIG. 5 is a schematic illustration of a stem/handle
interface in accordance with the teachings herein;
[0020] FIG. 6 is an illustration of the functionalities combined
into a mass flow controller made in accordance with the teachings
herein;
[0021] FIG. 7 is a functional illustration showing the fluid path
of a conventional thermal-based mass flow controller;
[0022] FIG. 8 is a schematic illustration of the fluid path of a
mass flow controller made in accordance with the teachings
herein;
[0023] FIG. 9 is a graph illustrating crosstalk in a conventional
fluid panel;
[0024] FIG. 10 is a graph illustrating the elimination of crosstalk
through the use of a mass flow controller made in accordance with
the teachings herein;
[0025] FIG. 11 is a schematic illustration of a process fluid
control assembly configuration made in accordance with the
teachings herein; and
[0026] FIG. 12 is an illustration of a fluid pallet made in
accordance with the teachings herein.
DETAILED DESCRIPTION
[0027] As used herein, the term "fluid" is meant to include both
liquids and gases.
[0028] It has now been found that the length of process fluid
control assemblies, and hence the size of fluid panels, can be
reduced by combining the functionalities of a manual valve and a
pneumatic valve (such as the first pneumatic valve 111 of FIG. 1)
into a single valve. The resulting combination manual/pneumatic
valve reduces the length of the process fluid control assembly and
the size of the fluid panel without adversely affecting the
serviceability of the fluid panel or process fluid control assembly
and the modularity thereof. It has also been found that further
reductions in the length of the process fluid control assembly and
the size of the fluid panel can be obtained, again without
adversely affecting the serviceability of the fluid panel or
process fluid control assembly and the modularity thereof, by
combining the functionalities of the pressure regulator, pressure
transducer, and filter of a conventional process fluid control
assembly such as that shown in FIG. 1 into the mass flow
controller. These and other aspects and features of the systems and
devices disclosed herein are discussed in greater detail below.
[0029] FIGS. 2 -4 illustrate one embodiment of a combination
manual/pneumatic valve 11 made in accordance with the teachings
herein. The combination valve has a housing 13 which is typically
cylindrical and which contains a centrally disposed expansion
chamber 15 and a centrally disposed valve chamber 17. The expansion
chamber and the valve chamber are typically coaxially aligned. The
valve chamber has a process fluid inlet 19 and a process fluid
outlet 21 defined therein, and is fitted with a diaphragm 23 and a
valve seat 25 that cooperate to control the flow of fluid into and
out of the valve chamber. Thus, when the diaphragm is spaced apart
from the valve seat, the process fluid inlet and process fluid
outlet are in open communication, and fluid is permitted to flow
into and out of the valve chamber. However, when the diaphragm is
compressed against the valve seat (that is, when the valve is if
the "off" position), the process fluid inlet and process fluid
outlet are isolated from each other, and the flow of fluid through
the valve chamber is terminated. Typically, the valve seat will
comprise an elastomeric material that has sufficient compliance to
achieve a tight seal when a sufficient compressive force is applied
to it, yet has sufficient resiliency to return to its original
shape when the compressive force is removed. The valve seat will
most typically comprise a fluoroelastomer which may be coated with
a perfluoropolymer, given the chemical resistance of the latter to
commonly used process fluids such as chlorine.
[0030] The expansion chamber 15 of the valve is typically
cylindrical and has a coaxially aligned and longitudinally
extending shaft 27 disposed therein. The shaft is connected on one
end via a mandrel 28 to an actuator 29 which makes contact with the
diaphragm 23, and terminates on the other end in a handle 31. The
shaft is fitted with a spring-loaded piston 33 which is maintained
under a minimum compressive force by means of a spring 35.
[0031] The handle is fitted with a threaded male cylinder 37 that
rotationally engages a complementary threaded female receptacle 39.
The handle is typically designed to be operated with an
ergonomically reasonable amount of force. Consequently, as the
handle is rotated in the (typically clockwise) disabling direction,
the shaft 27 is advanced along the longitudinal axis such that the
actuator compresses the diaphragm 23 against the valve seat 25,
thereby cutting off the flow of fluid between the process fluid
inlet 19 and the process fluid outlet 21 and manually placing the
valve in the disabled position. Conversely, when the handle is
rotated in the (typically counterclockwise) enabling direction, the
shaft is withdrawn along the longitudinal axis, and the valve is
returned to a pneumatically controlled state. In this state, and in
the absence of a pneumatic signal, the spring 35 continues to force
the piston 33, the shaft 27 coupled directly thereto, and the
actuator 29 against the diaphragm 23, thereby maintaining the valve
in a closed position. Hence, the handle provides a mechanism
whereby pneumatic control of the valve can be overridden solely for
the purposes of disabling the valve (that is, to stop the flow of
fluid). By contrast, the flow of fluid through the valve is enabled
only when the handle is in a manually enabled position and a
pneumatic opening signal is present. This aspect of the combination
manual/pneumatic valve is significant from a safety aspect, since
it does not allow manipulation of the valve to override the safety
interlock circuits that function by disabling the pneumatic
signal.
[0032] The housing 13 is also equipped with an air inlet 41 and an
air exhaust 43 which can be alternatively brought into open
communication with a central passageway 45 disposed in the shaft 27
by rotation of the handle 31. The central passageway is in open
communication with the portion of the expansion chamber disposed
below the piston. When the handle 31 is in a manually enabled
position as shown in FIG. 2--that is, when the central passageway
is in open communication with the air inlet, and when there is no
air signal (i.e., air pressure sufficient to displace the piston
against the spring is not applied) at the air inlet--the
compressive force exerted by the spring 35 against the piston 33
causes the actuator to press against the diaphragm, hence
maintaining the valve in a closed position.
[0033] When the handle 31 is in a manually enabled position as
shown in FIG. 3--that is, when the central passageway is in open
communication with the air inlet 41, and an air signal is present
(i.e., sufficient air pressure is applied at the air
inlet)--pneumatic pressure is applied to the spring loaded piston
33, by way of the central passageway 45. So long as the force
exerted by this pneumatic pressure is greater than the expansive
force exerted by the spring 35, the spring will be compressed, the
piston will be driven into abutment with a stop surface 47 on the
shaft, and the actuator 29 will be withdrawn along its longitudinal
axis. This, in turn, allows the diaphragm 23 to expand and bring
the fluid inlet 19 and outlet 21 into open communication with each
other, thereby permitting a flow of fluid through the valve
chamber.
[0034] In valves of the type depicted, the diaphragm is typically
driven upward by at least two forces. The first is that the
pressure of the fluid in the inlet 19 or outlet 21 imposes an
upward force on the diaphragm. The second is that the diaphragm's
resting shape is usually concave downwards, so that it flexes
unless it is being forced down against the valve seat 25. With
respect to this latter feature, it is to be noted that, in some
embodiments, the actuator 29 is not connected to the piston 33 by a
means that allows the piston 33 to pull the actuator 29. In these
embodiments, the upward motion of the piston 33 may simply allow
the actuator 29 to be moved upward by the flexion of the
diaphragm.
[0035] As shown in FIG. 4, when the handle 31 is in a manually
disabled position--that is, when the handle is manually rotated
such that the central passageway 45 is in open communication with
the air exhaust 43--the pressure in the expansion chamber is at
ambient pressure even if a pneumatic signal is present at air inlet
41. Moreover, the advancement of the shaft 27 along the
longitudinal axis as the handle 31 is rotated into a disabled
position drives the actuator 29 against the diaphragm 23.
Consequently, the valve is disabled by the longitudinal
displacement of the shaft that precludes the piston being moved
away from the diaphragm by the pneumatic signal.
[0036] The combination manual/pneumatic valve 11 may be lockable in
the disabled position using a padlock, a cable, or other available
locking devices (not shown). Hence, the valve may function as a
Lock Out Tag Out (LOTO) device. Moreover, to ensure safety in case
of failure in the fluid control components upstream of the manual
valve, the valve may also be designed to withstand an inlet
pressure of at least 3000 PSIA in the disabled position without
allowing fluids to pass through the valve for 72 hours
(irreversible damage to the valve is reasonable in this unlikely
scenario).
[0037] It will be appreciated from the above description that the
valve can be disabled manually or closed pneumatically, though
manual disablement is independent of the pneumatic input state.
Hence, the valve can be opened pneumatically to allow the flow of
fluid, only if it is manually in the enabled position, and the
valve can also be disabled manually to stop the flow of fluid, even
if a pneumatic signal to open is present. This feature of the valve
is highly advantageous from both an emergency shut-off and
maintenance aspect.
[0038] FIG. 5 illustrates the shaft/handle interface 61 of the
combination valve disclosed herein. This interface would typically
be disposed inside the threaded male cylinder 37 in the combination
manual/pneumatic valve depicted in FIGS. 2-4. The interface may be
machined onto, or soldered onto, one end of the shaft 27 in the
valve of FIGS. 2-4. The handle has a hollow cylindrical underbody
which is adapted to mate with a complimentary shaped male member
(shaft/handle interface FIG. 5) that protrudes from the shaft 27 of
the valve of FIGS. 2-4. The interface is also provided with an
aperture 65 which is adapted to receive an Allen screw or other
fastening device for securing a handle to the interface.
[0039] The shaft/handle interface 61 of FIG. 5 is advantageous in
that it can be provided on each component of the fluid panel that
requires a handle, thus allowing the fluid panel to be readily
standardized so that the same handle can be used to operate each
component of the panel. This also allows each component fitted with
the interface to be easily retrofitted and standardized as a LOTO
device. The dimensions of the features on the shaft/handle
interface 61 of FIG. 5 can vary.
[0040] The combination manual/pneumatic valve described above in
reference to FIGS. 2-4 has several important safety advantages over
many existing valves. One of these safety advantages relates to the
use of the combination valve to provide Lockout/Tagout (AKA, LOTO,
Hazardous Energy Isolation (HEI)). For example, reduction in fluid
panel size could be obtained by placing a conventional lockable,
manually-operated valve in the pneumatic control line to the
valves, and this would permit the disabling of pneumatic control in
a manner that would arguably meet the regulatory requirements for
Lockout/Tagout devices. However, this approach is flawed in that
the energy isolation could be subverted by connecting (deliberately
or accidentally) another source of actuating pressure to the
process fluid valve. For example, an accidental connection could be
the result of an attempt to connect a control line to a different
valve, or from the connection of the manually operated valve to a
process chemical valve other than the one the person intended to
isolate.
[0041] In addition, overriding the pneumatic control signal of a
normally disabled valve leaves the valve in a state in which it
relies on the spring force being greater than the force applied to
the underside of the diaphragm by the fluid to keep the valve
disabled. Valves can be made in accordance with the teachings
herein that eliminate these flaws by disconnecting the pneumatic
control within the valve assembly (preventing cross connection of
control lines) and by providing a rigid mechanical linkage that
applies closing force to the diaphragm (reducing the dependence on
spring pressure to overcome the opening force applied by the gas).
Notably, the opening force applied by a fluid of a given pressure
at the valve outlet is approximately an order of magnitude greater
than the opening force applied by a fluid of the same pressure on
the fluid inlet. Consequently, the valves which rely on a spring to
maintain closure are subject, when disabled, to reverse flow at
much lower pressure than that at which they are subject to forward
flow.
[0042] Another safety advantage is that the combination of the
manual override and pneumatic actuation into a single valve renders
moot the competition for first (closest to the point of connection
to the fluid supply) position between pneumatic and manual valves.
The manual valves, as described previously, are used to isolate the
downstream fluid panel elements and the process chamber from the
fluid supply. The safety advantage of placing the manual valve
first is that it is then positioned to isolate all of the other
elements of the fluid panel from the supply. This minimizes the
chance of accidental release (either from component failure or
human error) by minimizing the number of components that are still
connected to the supply.
[0043] The pneumatic valves serve a different safety function. They
may be used as the actuating elements of several interlock circuits
that, in response to various conditions, disconnect the fluid
supply from the elements of the fluid panel downstream of them and
from the process chamber. Among the sensors in such interlock
circuits are fluid detectors. If the detectors sense a leak and
remove the actuating signal from a valve, control of the flow
through the leak depends on whether the leak is upstream or
downstream of the valve which is no longer being actuated.
Therefore, it is advantageous in many applications to have the
pneumatic valve that is the actuating element for such interlocks
as far upstream in the assembly as possible. Consequently, the
manual and pneumatic valves "compete" for the first position. As
noted above, the combination valve described herein renders this
matter moot, as the same valve is subject to control by both
means.
[0044] The combination manual/pneumatic valve described above and
illustrated in FIGS. 2-4 enables significant reductions in process
fluid control assembly length and fluid panel size by combining the
functionalities of a pneumatic valve and manual shut-off valve into
a single component. However, it has also been found that even
further reductions in the length of the process fluid control
assembly and in the size of the fluid panel can be obtained,
without adversely affecting the serviceability of the fluid panel
or process fluid control assembly and the modularity thereof,
through modifications to the MFC. The resulting MFC is referred to
herein as a "Pressure Insensitive MFC" (PIMFC). As seen in FIG. 6,
the PIMFC 71 combines into a single unit the functionalities of a
pressure regulator 73, pressure transducer 75, filter 77, and MFC
79 as those elements are found in a conventional process fluid
control assembly such as that shown in FIG. 1. The PIMFC is
described in greater detail below.
[0045] FIG. 7 is a functional illustration of a conventional
thermal-based MFC 81. The MFC consists primarily of a control valve
83 and a thermal flow sensor 85. The use of an MFC of this type
necessitates the use of a pressure regulator to eliminate
"crosstalk", that is, pressure perturbations in the supply line
supplying fluid to a first process fluid control assembly that can
occur when a second process fluid control assembly operating from
the same fluid source is brought online. Crosstalk commonly occurs
when the second process fluid control assembly is supplying the
fluid at a significantly higher pressure than the first fluid
control assembly. Such pressure perturbations cause the MFC
controlling the first process fluid control assembly to temporarily
register an indicated fluid flow rate that is substantially
different (typically much lower) than the actual flow rate.
[0046] The effect of crosstalk in a process fluid control assembly
controlled by a conventional MFC (and without the aid of a
regulator) is shown in the graph of FIG. 9. This graph was
generated on a test station using a stimulus MFC to create a
pressure perturbation of about 3 psi (20.7 MPa). The curve denoted
"XDOR6" indicates pressure in the fluid line as a function of time
as measured by a pressure transducer. The curve denoted "indicated
flow" is the fluid flow through the process fluid control assembly
as indicated by the MFC, while the curve denoted "ROR" is the Rate
of Rise flow, a standard measurement of the actual fluid flow in
the fluid control assembly.
[0047] After the initial perturbation of about 3 psi (20.7 MPa),
the pressure perturbation relaxed to a pressure difference of about
2 psi (13.8 MPa). However, during the initial perturbation, the
difference in indicated and actual fluid flow at the MFC was about
3 sccm. This demonstrates the tendency of the MFC, in the absence
of a pressure regulator, to overcompensate for the initial pressure
drop in the fluid supply at the process fluid control assembly
inlet by ramping up the actual flow rate. The use of pressure
regulators is thus necessitated with conventional MFCs of this
type. The pressure regulator functions by controlling crosstalk by
dampening out the pressure perturbations giving rise to crosstalk.
This, in turn, allows the indicated flow rate to more closely track
the actual flow rate.
[0048] FIG. 8 is a functional illustration of a PIMFC 91 made in
accordance with the teachings herein. The specific details of the
components of the PIMFC may vary significantly from one product to
another, and have been omitted for purposes of clarity. However,
these components are individually well understood in the art, and
hence one skilled in the art will appreciate various specific
implementations from the functional presentation of these
components here.
[0049] As with the conventional MFC illustrated in FIG. 7, the
PIMFC also contains a control valve 93 and a thermal flow sensor
95. However, the PIMFC additionally contains a pressure sensor 97
and a filter 99. The pressure sensor is upstream of the flow sensor
and can be tied into the control loop operating the control valve.
Consequently, the PIMFC can rapidly compensate for any changes in
the inlet pressure through suitable manipulation of the valve.
Since the PIMFC is thus adapted to deal with pressure perturbations
in the fluid control assembly, the need for a separate regulator is
eliminated. Moreover, since the filter 99 in a conventional process
fluid control assembly exists primarily to filter out from the
fluid stream debris created by the pressure regulator before the
fluid stream enters the MFC, the need for a stand-alone filter is
also eliminated. Consequently, the filter may be simplified and
incorporated directly into the PIMFC 91 to protect the sensors and
actuators from particulate accumulation generated elsewhere
upstream. Also, since the PIMFC already contains a pressure sensor,
there is no need for an external pressure transducer, and the
display functionalities associated with the pressure transducer may
be incorporated directly into the PIMFC (that is, the PIMFC may be
provided with a display to indicate the pressure already being
measured by the pressure sensor).
[0050] FIG. 10 illustrates the effectiveness of the PIMFC disclosed
herein in eliminating crosstalk in a process fluid control assembly
without the use of an external pressure regulator. As with the
conventional MFC that was the subject of the graph in FIG. 8, the
PIMFC was subjected to an initial pressure perturbation of about 3
psi (20.7 MPa), after which the pressure perturbation relaxed to a
pressure difference of about 2 psi (13.8 MPa). However, unlike the
conventional MFC, the PIMFC closely tracked the actual fluid flow
rate through the process fluid control assembly during the entire
perturbation. This demonstrates that the PIMFC, unlike a
conventional MFC, will not overcompensate for pressure
perturbations, and hence does not require the use of a separate
pressure regulator.
[0051] FIG. 11 illustrates a process fluid control assembly 131
made in accordance with the teachings herein which is suitable for
use with toxic fluids and which incorporates the combination
manual/pneumatic valve and PIMFC described above. The process fluid
control assembly comprises a combination manual/pneumatic valve 133
of the type illustrated in FIGS. 2-4, first 135 and second 137
pneumatic valves, and a PIMFC 139. The first 135 and second 137
pneumatic valves allow the flow of fluid to be remotely turned on
and off by sending an electronically controlled pneumatic signal
(pressurized air) to both pneumatic valves. A communications port
141 is provided on the mass flow controller to allow it to be
accessed and controlled remotely. This communications port, which
may be adapted to accept wires, optical cables, and other such
communications means, may be situated on various surfaces of the
mass flow controller and may have various configurations.
[0052] In contrast to the conventional process fluid control
assembly of FIG. 1, which requires a pressure regulator 105,
pressure transducer 107, and filter 109, in the process fluid
control assembly 131 of FIG. 11, the pressure regulator has been
eliminated and the functionalities of the remaining elements have
been combined into the PIMFC 139 as described above. Consequently,
pneumatic valve 113 of FIG. 1 is no longer required, since the
aforementioned elements can be isolated for purging or maintenance
in the process fluid control assembly of FIG. 11 via the first 135
and second 137 pneumatic valves. Furthermore, pneumatic valve 111
of FIG. 1 has been combined into the manual/pneumatic valve 133 in
the process fluid control assembly of FIG. 11, also as described
above. Therefore, the process fluid control assembly of FIG. 11 is
sufficiently more compact than the conventional process fluid
control assembly of FIG. 1. This compact design also simplifies
pallet design for the fluid panel and reduces the cost thereof.
Moreover, because the process fluid control assembly of FIG. 11 has
fewer components than conventional process fluid control assemblies
such as that shown in FIG. 1, Mean Time Before Failure (MTBF) is
higher for the entire system, and thus maintenance costs are
reduced.
[0053] The process fluid control assembly 131 of FIG. 11 is adapted
for use with toxic fluids such as chlorine. However, one skilled in
the art will appreciate that the principles herein may also be
extended to process fluid control assemblies adapted for use with
inert fluids. This may be accomplished, for example, by modifying
the process fluid control assembly of FIG. 11 through the
elimination of pneumatic valves 135 and 137.
[0054] FIG. 12 depicts one non-limiting example of a fluid panel
151 which incorporates a series of process fluid control assemblies
153 of the type depicted in FIG. 11. In a typical configuration,
some of the process fluid control assemblies (typically the first
six, going from left to right) control toxic, corrosive or
flammable fluids, and the remainder of the process fluid control
assemblies control the flow of inert fluids. These two types of
process fluid control assemblies are referred to herein as toxic
process fluid control assemblies and inert process fluid control
assemblies, respectively.
[0055] Each of the process fluid control assemblies is supported on
a common pallet 155 and comprises a combination manual/pneumatic
valve 157 (of the type illustrated in FIGS. 2-4), first 159 and
second 161 pneumatic valves, and a PIMFC 163 equipped with a
communication port 165. The fluid panel further includes a main
manifold 167 where various process fluids under the control of
individual process fluid control assemblies can be mixed to form a
fluid stream. The fluid stream exits the main manifold via the main
manifold outlet 171, from which it can be directed to a process
chamber (not shown) or other end use device.
[0056] The main manifold is provided with a fluid inlet 173 and a
fluid outlet 175 that allow it to be flushed with an inert fluid
such as N.sub.2 for maintenance purposes or to clear it of residual
toxic fluids. The fluid flow through fluid inlet 173 and fluid
outlet 175 may be controlled by purge valve 177, in addition to one
or more of the other valves on the main manifold. A fluid line 179
is provided through which the main manifold 167 and a purge
manifold 160, the latter of which is disposed under the set of
first pneumatic valves 159, can be brought into open communication,
thus allowing the PIMFCs 163 to be isolated for maintenance or
other purposes.
[0057] The main manifold 167 is provided with a first, second and
third pair of valves that respectively consist of first 181, second
185 and third 189 inlet valves and first 183, second 187 and third
191 outlet valves. The first 183 and second 187 outlet valves are
pneumatically coupled, with the first outlet valve operating to
control the flow of inert fluids from the inert process fluid
control assemblies into the main manifold, and the second outlet
valve operating to control the flow of toxic fluids from the toxic
process fluid control assemblies into the main manifold. Thus, for
example, the first six process fluid control assemblies (from left
to right) may be under control of the second outlet valve 187, and
the next six process fluid control assemblies may be under control
of the first 183 outlet valve. Hence, when the first 183 and second
187 outlet valves are both enabled, the fluid streams from any
enabled inert process fluid control assemblies will mix with the
fluid streams from any enabled toxic process fluid control
assemblies inside of the main manifold 167 and the resulting mixed
fluid stream will exit the main manifold through the main manifold
outlet 171.
[0058] The fluid panel 151 is further provided with pass-through
valves 181 and 185. These pass-through valves, which are kept
enabled during normal operation of the fluid panel, cooperate with
the first 183 and second 187 outlet valves, respectively, to
regulate the flow of fluid through the pump/purge manifold 186 and
to allow for bidirectional pumping and purging of the fluid
panel.
[0059] The third outlet valve 191 on the fluid panel regulates the
flow of fluid through inlet 173 for purging and maintenance of the
fluid panel. Similarly, the third inlet valve 189 regulates the
flow of fluid into the pump/purge manifold 186 for purging and
maintenance purposes. Thus, for example, if the third inlet valve
189 is disabled and the third outlet valve 191 is enabled, then
fluid can be made to flow through fluid line 179 and subsequently
through the purge manifold 160 under the set of first pneumatic
valves 159 so that toxic fluids can be purged from the toxic
process fluid control assemblies.
[0060] The principles disclosed herein have been described
primarily with reference to combination manual/pneumatic valves and
to the use of such valves in process fluid control assemblies.
However, it will be appreciated that the manual/pneumatic actuators
described herein have a number of applications that extend beyond
process fluid control assemblies. For example, such actuators could
be employed in various latching systems, such as those used in
industrial and high security settings. In such applications, the
manual/pneumatic actuators would maintain the latch in a closed
position (and therefore maintain a door, hatch or other device
under control of the latch in a closed position) unless a pneumatic
signal is present. Moreover, even if a pneumatic signal is present,
the manual/pneumatic actuator would allow for manual override of
the pneumatic signal for safety, security or maintenance
purposes.
[0061] More generally, the principles disclosed herein may be
applied to devices in which an energy input is provided to cause
the movement of one or more movable components of the device. Such
devices may be modified in accordance with the teachings herein to
effect, as the result of a single manipulation of a manual control,
the disconnection of the energy input and the engagement of a
mechanical means of keeping the movable component (or components)
from moving. Specific, non-limiting examples of such modified
devices include valves in which the energy input is a control
signal that allows a hazardous material to flow, and latches in
which the energy input is a control signal which allows access to a
hazardous area. The modified device could also be a manual valve
that controls actuation air to a pneumatically powered device
(e.g., a gate valve), and that includes a mechanism that, in the
disabled state, engages a mechanical lock on the pneumatically
powered device, precluding movement of one or more pneumatically
driven components of the device.
[0062] It will also be appreciated that, while the principles
disclosed herein have been frequently illustrated in reference to
pneumatically actuated devices, these principles are also
applicable to devices having various other energy inputs and
actuating signals. Such energy inputs include, but are not limited
to, electrical and fluid (e.g., hydraulic) signals.
[0063] A combination manual/pneumatic actuator has been described
herein. A combination manual/pneumatic valve has also been
described herein that utilizes such an actuator and that combines
the functionalities of a manual valve and a pneumatic valve into a
single valve. This combination valve allows for reductions in the
length of process fluid control assemblies and of fluid panels
incorporating these process fluid control assemblies, without any
loss in functionality, ease of serviceability and modularity. Fluid
panel configurations that make advantageous use of the shortened
process fluid control assemblies have also been provided.
[0064] All the features disclosed in this specification (including
any accompanying claims, abstract and drawings), and/or all of the
steps or any method or process so disclosed, may be combined in any
combination, except combinations where at least some of the
features and/or steps are mutually exclusive. Each feature
disclosed in this specification (including any accompanying claims,
abstract and drawings) may be replaced by alternative features
serving the same equivalent or similar purpose, unless expressly
stated otherwise. Thus unless expressly stated otherwise, each
feature disclosed is one example only of a generic series of
equivalent or similar features. Moreover, although a specific
embodiment is specifically illustrated and described herein, it
will be appreciated that modifications and variations of the
invention are covered by the above teachings and within the purview
of the appended claims without departing from the spirit and
intended scope of the invention.
* * * * *