Note: Descriptions are shown in the official language in which they were submitted.
~U5~409
VALVE POSITIONING HANDLE
Background of the Invention
Field of the Invention. This invention relates to a valve
positioning handle and, more specifically, to such a handle which is
designed to prevent the application of excessive forces to the valve
during valve positioning which might cause damage or destruction to the
valve or the piping in which it is installed.
Description of the Prior Art. There ls an increasing demand
for plastic valves to be utilized in association with plastic pipe in
the gas distribution field. It is of continuing concern that these
valves be designed to ensure that the system integrity will be main-
tained under adverse operating conditions. Federal operating standards,
for example, require plastic pipe to be able to withstand pressures up
to about 100 p.s.i. under operating temperatures ranging from 20 F to
+100 F. Valves utilized with this pipe should satisfy similar re-
quirements. Throughout this range of temperatures and pressures there
is created a change in the characteristics of the plastic which com-
plicates the basic problem of system reliability.
- Specifically, it has been recognized that if the valve became
jammed during efforts to open or close it, a situation could develop
whereby a loss of system integrity might follow. Customarily, these
; valves are lacated underground and are operated by field service personnel
with a variety of metal, torque applying tools. It is felt that if a
valve became jammed, these rugged tools could be utilized to apply an
excessive force to the isolation member and the body which could destroy
the plastic valve or pipe. A crack or fracture in the isolation member,
body or pipe could allow an uncontrolled escape of gas which would
endanger personnel and property in the area.
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Summary of the Invention
It is therefore an object of th;s ;nvent;on to prov;de a valve
positioning handle which can be operated by a tool without allowing the
applicat;on of an excessive rotational force thereby which could destroy
the ;ntegr;ty of the valve or p;pe.
It is another object of this invention to provide a valve
pos;t;oning handle of the type described which can be inexpensively
provided for reliable valve operation under normal conditions.
It is still another object of this invention to provide a
valve pos;t;on;ng handle wh;ch can accommodate a number of torque
applying tools com~only utilized for valve operation in the gas dis-
tribution field.
To accomplish these and other objects of the present invention,
a preferred embodiment includes a valve positioning handle for a plastic
valve wh1ch is capable of be;ng utilized in a pressurized fluid dis-
tribution pipe, has a central axis and includes a body and a fluid
isolation means disposed therein for rotation about the axis. The valve
and distr;bution pipe are capable of being destroyed or demaged by the
application of excessive forces to the isolation means and the body
during rotat;on. The valve pos;tion;ng handle includes an extended
fitting centrally aligned with the axis and having working surfaces
thereon for the receipt of either of a pair of commonly used torque
applying tools. A connecting section between the extended fitting and
the isolation means is formed of a pre-selected material and has pre-
determined cross-sectional dimensions relative to the axis in a plane
perpendicular to the axis to ensure its failure prior to the generation
of the excessive forces by the tool being utilized to rotate the extended
fitting.
Brief Description of the Drawings
3~ Figure l is a perspective view of the preferred valve positioning
handle including various features of the invention.
lOS14U9
Figure 2 is a top view of the handle shown in Figure 1.
Figure 3 is a side view of the handle shown in Figure 1.
Figure 4 is an end view of the handle shown in Figure 1,
including, for example, one type of isolation member on which it may be
mounted.
Detailed Description of the Drawings
As seen in a perspective view in Figure 1, a preferred valve
positioning handle 10 is utilized to open and close a valve 12. The
valve 12 includes a body 14 and a fluid isola~ion member 16 which is
disposed within the body 14 for rotation about a central axis of the
valve 12. The valve 12 is preferably formed of a plastic material and
is of the type which can be utilized in a pressurized gas distribution
piping (not shown) which is commonly located undergroùnd and subjected
to varying environmental conditions.
Also shown in Figure 1 in phantom are two torque applying
tools most often utilized by field service personnel in the operation of
isolation valves in this type of system. A first tool 18 is formed of
heavy metal and typically includes a T handle ~not shown) connected to
an extended shaft 20. An inverted U-shaped wrench 22 is centrally
aligned with the shaft 20 to include a parallel pair of depending,
separated leg planes 24. The leg planes 24 are to be positioned at
opposite working sides of a valve operating handle to enable the service
personnel to rotate the tool 18 for selective positioning of a valve. A
second tool 26 is also formed of metal and includes an operating shaft
(not shown) which terminates at a square-shaped wrench 28 at its lower
end. The square-shaped wrench 28 has four side planes 30 of equal
length, usually two inches, to be positioned about a matching square
valve fitting for rotation of the valve isolation member. The tools 18
and 2S have heretofore been used on valves having different operating
fittings according to size and/or manufacturer's design but are both
quite commonly used in the gas distribution field.
lOS1~09
As seen in Figures 1 through 4, the preferred valve positioning
handle 10 includes an extended fitting 31 which is adapted to selectively
accommodate both torque applying tools 18 and 26. The extended fitting
31 is provided a plurality of working surfaces which are generally
parallel with the valve axis and specifically includes a pair of opposed
surfaces 32 against which each leg plane 24 can be located to rotation
by the first tool 18. Other working surfaces include a quadruplet of
surfaces 34 which are properly spaced and oriented to respectively
receive thereby each side plane 30 of the second tool 26 should it be
utilized for valve operation.
As discussed hereinabove, it is of concern that while the
heavy, metal tools 18 and 26 are capable of properly positioning a
valve, they are structurally capable of being used to generate an
excessive force during rotation which could destroy a plastic valve or
the plastic distribution piping extending at either side thereof. This
would be equally true if some other rugged torque applying tool, such as
one with an adjustable wrench fitting, were alternatively employed.
Accordingly, the preferred handle 10 includes a connecting
section 36 between the extended fitting 31 and the end 38 of the isolation
member 16 on which the handle 10 is mounted. The connecting section 36
is designed to fail under torsional stress before the tool could be
utilized on the extended fitting 31 to generate the undesired excessive
force within the valve 12 or the pipe. It is known that the maximum
torque about a given axis which a section can withstand is a function of
the material and the cross-sectional dimensions of the section relative
the axis in a plane which is perpendicular to the axis. For a pre-
selected material, the ultimate shear stress can be obtained from an
engineering material handbook. When the cross-sectional dimensions
relative to the axis are predetermined, the polar moment of inertia and
the distance from the axis to the most extreme portion of the section
(the point at which shearing will begin) can be determined. The
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ultimate shear stress, the polar moment of inertia and this distance are
used to calculate the maximum torque which the section can withstand.
By way of example, a typical valve configuration might include
an isolation member 14 in the form of a plastic cylindrical plug 40 as
shown in Figure 4. Preferably, the plug 40 and the handle 10 are integrally
formed by molding of the same plastic material. Although not shown in
the drawings, it was determined by accepted engineering analysis and
calculat~ons that both the body 14 and the piping were stronger than the
plug and that neither would, in this configuration, be the first element
to fail under an excessive force which might be generated by use of the
tool. The plug 40 includes a port 42 which is aligned with the passages
in the pipe for flow through the valve 12 when in the opened position.
A pair of recesses 44 at opposite sides of the plug 40 respectively
receive a pair of resiliently deformable sealing members tnot shown
since that would offer little resistance to torsional failure of the
plug 40) which sealing members are to be aligned with the pipe passages
when the valve 12 is closed to prevent fluid flow therethrough. The
plug 40 therefore has its smallest cross-sectional area at an intermediate
plane A where two separated, structural portions 46 join the opposite
ends of the plug 40 and would fail in this region if subjected to an
excessive torque. The portion of the connecting section 36 at which
shearing should first occur under torsional stress is shown in Figure 4
at plane B.
Mathematical shearing analysis ~as conducted for a plug and
handle configuration formed of plastic material having at least an
ultimate shear stress of approximately 20,000 p.s.i. throughout the
expected operating temperatures. The plug 40 had a diameter of about
two inches and the connection section 36 had a length of about 2.35
inches and an effective width of about .25 inches. The results of the
analysis indicated that the connecting section 36 would shear at plane B
with a torque of about 76 foot-pounds but that 128 foot-pounds torque
105i4~19
would be required to shear the plug along plane A where the reduced
cross section is located. Laboratory tests were then conducted on such
a plug and handle and it was found that the average torque required to
break the connecting section was about 80 foot-pounds while about 200
foot-pounds were required for the plug 40 in the region of the port 42.
While the analysis and tests above were conducted for a con-
figuration which exemplifies the purpose of the invention, it should be
apparent that a connecting section of different shape or material might
be utilized to protect any number of valve configurations. For example,
the valve might be a ball valve, or the valve body might be the weakest
element, or the isolation member might be formed of a different plastic
material from the handle, or the connecting section might be mechanically
rather than integrally joined to the isolation member. One skilled in
the valve manufacture and construction art should be capable of analyzing
the particular configuration to ensure that the connecting section would
fail prior to destruction of the valve or pipe.
While breaking the handle, even if valve operation is lost, is
obviously preferable to having a dangerous loss of system integrity
which would allow the escape of gas, failure of the connecting section
36 is not desired unless needed for this purpose. Unfortunately, designed
weakening of the connecting section 36 to ensure failure under excessive
torque, leaves it vulnerable to damage by the application of other types
of force. Being located underground and being operated by heavy torque
applying tools makes the handle particularly susceptible to impact force
from any number of sources from above the valve, such as might occur
from a dropped tool. The possibility of undesired breakage is increased
at lower temperatures as the plastic becomes more brittle. It is
therefore desirable to deflect any tool, rock or other object from
direct impact on the handle if dropped from above. Therefore, a plurality
of facets 48, 50 and 52 are located at the top of the extended fitting
31 and are do~nwardly inclined from the valve axis for this purpose.
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Since an impact force m;ght be created by field service personnel
striking the handle 10 with a tool when it is not properly aligned with
the working surfaces, the facets 48 and 50 are respectively aligned with
the working surfaces 32 and 34 to facilitate alignment and decrease the
likelihood of damage by this occurrence.
There are in the preferred valve positioning handle 10 additional
features which facilitate reliable valve operation. It is not uncommon
for a pair of position stop devices 54 to be provided on the body 14 to
ensure the valve is in the proper opened or closed position as desired
after rotation. A position indicator is usually mounted on the isolation
member to make contact with the stop device 54. In the preferred handle
10, a pair of position indicating tabs 56 are provided for this purpose
and are integrally formed with and extend from the connecting section
36. In Figure 1, the valve 12 is shown in the opened position as
evidenced by the tabs 56 being aligned with flow direction arrows 58
formed on the body 14. It is also desirable, as with the handle 10, to
prevent damage to the tabs 56 by a tool being dropped or roughly positioned
around the extended fitting 31. Since a blow to the handle 10 or the
isolation member 16 might cause a slight, rapid axial movement of the
isolation member 16 with respect to the body 14, the tabs 56 are axially
separated from the body 14, as at 60, to allow limited axial movement
thereof free of contact with the body 14 which could break the tabs 56.
Additionally, the tabs 56 are axially lower than the extended upper
surface 62 of the position stop devices 54. This positioning insures
that when the tool 26 is used, it will make contact with the surfaces 62
rather than with the tabs 56 during valve positioning when the tabs 56
could otherwise be damaged or broken.
While there has been shown and described herein a preferred
embodiment of the invention, it will be obvious to those skilled in the
art that changes and modifications may be made therein without departing
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from the invention as claimed. For example, it should be apparent that
a handle may now be provided for use on any number or type of valves in
the gas distribution field which handle ~ill accommodate both commonly
used tools 18 and 26. This type of handle can be advantageous even if
it does not include a breakable connecting Section and is not primarily
intended to protect a plastic valve.
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