Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CONDUIT CLAMP
sackground of the Invention
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This invention relates to a clamp for clamping a conduit,
a pipe or the like to a support, and more parti-cularly to such a
clamp which can accommodate any conduit having an outer diameter
which ranges between a specified minimum diameter and a specified
maximum diameter.
Generally, electrical conduits, pipes, etc., routed over-
head in buildings or through pipe tunnels are supported at spaced ;
intervals by channel-shaped supports. These channeI supports con-
ventionally have spaced side flanges with inwardly turned, hook-
shaped outer lips forming a slot therebetween. The conduits are ;
supported on the outer edges of these flanges and extend generall~
perpendicularly to the channel. Often, multiple runs oE conduit
or pipe are supported by the channel supports with the conduits
spaced closely to one another, but not touching one another.
Conventional clamps used to secure the conduits in placeon the support channeIs utilize a pair of clamping straps of solid
sheet metal or the like, one for each side of the conduit. Each
of these straps is insertabIe into the slot in the channel for en-
gagement with the above-mentioned lips of the channel. Generally,
known prior art clamping straps are accurately preformed so that
they conform to the outer surface of a conduit having a specified `
outer diameter. The outer ends of these prior art clamping straps
are typically bolted together so as to hold the conduit on the sup-
port channel.
Because these prior art conduit clamps are accurately
preformed to match the curvature of a particular size conduit, they
are not suited for clamping different sizes of conduit. Generally,
conduit and tubin~ come in a variety of nominal sizes and are avail-
able with wall thicknesses of thin or intermediate construction or
as standard tubing having a somewhat greater wall thickness. With
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known prior art clamps, a different clamp must be used for clampin~
thin wall conduit, intermediate wall conduit, or standard tubing,
even if the nominal size of these conduits or tubing is the same.
This necessitates stocking a large~number of clamps. Because a
different size clamp must be used for each size and type of con-
duit or pipe to be'clamped~ a workman on the job may not have the
proper size clamp readily available. Thus, either the workman must
stop his work to obtain the proper clamp which wastes considerable
time or he may attempt to use another size clamp which results in
improper clamping of the conduit.
It is conventional that conduit clamps be required to
withstand a specified load applied to the conduit which tends to
pull it away from its support channel.
Summary of the Invent'ion
Among the many objects of this invention may be noted
the provision of a conduit clamp which'can accommodate any conduit
or other circular cross-section member having an outer diameter
within a specified range of diameters; the provision of such a
clamp which will greatly lessen the number of sizes of clamps
which must be stocked to clamp thin wall conduit, intermediate wall
conduit and standard piping in a range'of specified nominal sizes; '
the provision of such a clamp which securely locks any conduit
within a specified range of outer diameters to a support channel;
the provision of such a clamp which will withstand a maximum speci-
fied load and hold the conduit on its support channel; the provision
of such a clamp which'substantially lessens the chances of a work-
man clamping a conduit with the wrong size clamp; and the provision
of such a clamp which is economical to manufacture and easy to in-
stall. Other objects and features of thi's invention will be in part
apparent and in part pointed out hereinafter. ;
Briefly, a clamp of this invention is provided for clamp-
ing a member of generally circular cross-section, such as a conduit
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or the like, to a channel having side flanges. each having an in-
wardly airected, hook-shaped lip defining a slot therebetween
with the member extending generally perpendicular to the channel -
and engaging the outer edges of the lips. The clamp of this in-
vention is adapted to clamp any of a plurality of the above- ;
mentioned members having outer diameters ranging from a specified ..;
minimum diameter to a specified maximum diameter. The clamp com- ~.
prises a pair of clamp straps, one for each side of the member, ....
each of which comprises a generally flat stem portion of a width
less than the width of the slot, and an ear at each lateral side .
of the stem extending out beyond a respective side o the stem
for engagement with one of the lips. An intermediate portion is
bent out of the plane of the stem to extend around and grip a por-
tion of the surface of the member to be clamp~d, and an out~r end ;
portion extends from the intermediate portion. Means is provided
engageable with the outer end portions of the head portion for .
drawing together the straps on opposite sides of the member. The
intermediate portion of each strap has a cutout therein and bridge : .
portions on opposite sides of the cutout, these bridge portions .
being adapted to conform to the outer surface of the member upon ~. .the straps being drawn together. The cutout, the bridge portion and
the ears are so structured that the tensile strength of the bridge
portion only slightly exceeds the strength of the ears so that upon
application of a force which tends to pull the member away from the .; .
channel, the ears will fail prior to failure of the bridge portions. ::~
Brief Description of *he Drawings i.
.
Fig. 1 is a perspective view of two identical clamps o~
this invention clamping two conduits of different outer diameters `
to a channel-shaped support;
Fig. 2 is an enlarged side elevati.onal view of a clamping :
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strap of the clamp of the present invention; and
Fig. 3 is an edge view of the clamp of this invention
with portions of the clamping strap broken away. ,~.
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Corresponding reference characters indicate correspond-
ing parts throughout the several views of the drawings.
Brief Description of a Preferred Embod'iment
Referring now to the drawings/ a clamp of this invention,
indicated in its entirety at 1, is shown clamping a conduit of cir-
cular cross-section to a channel-shaped support. In accordance ;~
with this invention, clamp 1 is adapted to clamp any of a plurality
of conduits or pipes having outer diameters ranging from a speci-
fied minimum outer diameter (Dl, as indicated on a conduit 3 in
Fig. 1) to a specified maximum outer diameter (D2, as indicated on
conduit 4). For example, one size of clamp 1 will clamp all con-
duits having outer diameters ranging from 1.16" (29.5 mm.) to 1.32"
(33.5 mm.1 thereby to enable the clamp of this in~ention to clamp
thin wall conduit, interme~iate wall conduit and standard piping
all having a nominal inside diameter of 1" (25.~ mm.). Heretofore,
three different clamps were re~uired to clamp the same three con-
duits. More particularly, the clamp of this invention is adapted
to clamp a conduit to a channel-shaped support 5. This support or
channel has a pair of side flanges 7a, 7b, the outer ends of which
each have'a respective inwardly directed, hbok-shaped lip 9a, 9b
formed thereon. Th se lips are spaced from one another and define ~ -
a slot S therebetwee~n which extends the length of the channel. As ;
is best shown in Fig. 1, the conduits bear against the outer edges
of flanges 7a, 7b and extend generally perpendic~ularly -to the chan-
nel.
Clamp 1 has a pair of identical clamp straps lla, llb,
one for each side of conduit 3. Each strap has a generally flat
stem portion 13 of a width less than the width of slot S. The stem
has an ear 15a, 15b at each'side ther'eo'f extending out beyond the
side edge oE the stem portion for engagement with a corresponding
lip 9a, 9b of channel' 5. ~s shown in Fig. 2, ears 15a,15b are
hook-shaped and are adapted to positively engage lips 9a,9b. The ;
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strap further has an intermediate portion r as generally indlcated
at 17~ extending from the stem portion. This interme~iate portion
is bent out of the plane of the stem portion tsee Fig. 3) and it
extends around and grips a portion of the outer surface of conduit
3 to be clamped. Specifically, this intermediate portion is formed
to have a radius o curvature which corresponds to a conduit having
an outer diameter equal to the above-speci~ied minimum outer diame- ;
ter Dl of the range of conduit diameters that one size clamp of
this invention may accommodate. Upon the clamp being applied to a
conduit having a diameter ranging between the specified diameters
Dl and D2 or that clamp, and upon being drawn together in a manner
as will be hereinater speciied, the intermediate portions oE the
~.... .
straps will conorm to the radius o curvature oE the conduit being
clamped.
Each strap lla or llb is shown to have a flat outer end
portion 19 generally parallel to its stem portion 13 and a bend
line 20 constituting a transition between its intermediate and
outer end portions. As shown in Fig. 3 r stem portions 13 of straps
lla, llb are spaced apart by the outer diameter of the conduit to be
clamped and the outer end portions 19 of the straps are spaced close-
ly relative to one another. Each outer end portion has an aperture
21 therethrough for reception of a clamping bolt 23, the latter `
threadably receiving a nut 25 which when tightened draws the outer
end portions of the straps together. Apertures 21 are spaced from
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bend line 20 a suficient distance to enable bolt 23 to be inserted
therethrough and to permlt the bolt to be threaded into the nut,
with the nut being held against turning by the bend line.
As indicated at 27, each clamp strap lla,llb has a cutout
or window through its intermediate portion 17 thus deining bridge ~`
portions 29a, 29b on opposite sides of the cutout. Cutout 27
weakens the intermediate portion and thus enables the bridge por~
tions to bend so as to conform to the outer surface of the conduit
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S ..
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being clamped as straps lla, llb are forcibly drawn together by
bolt 23. Pre~erably, the clamp straps are made of reIatively
stiff, sheet metal or the like having a uniform thickness. For '
example, the straps may be made of mild commercial steel, stainless
steeL or aluminum. It is desirabIe upon applica'tion of a force
to the strap or conduit which tends to pull the'conduit away from ''
channel 5 that ears 15a, 15b fail prior to the failure of any por- ' '
tion of the strap, and more particularly fail prior to the failure
of bridge portions 29a, 29b. In order to insure that intermediate
portion 17 of each strap is as flexible as possible so as to enable
the strap to readily conform to the outer surface of a conduit 3 to -~
be clamped, and in order to insure'that ears 15a, 15b fail prior to
any other portion of the strap, bridge'portions 29a, 29b, cutout 27
and the ears of a clamp of this invention are'so structured relative
to one another that the strength oE the bridge portion~ only slight-
ly exceeds the strength o~ the ears so as to insure that the ears
will fail prior to the bridge portions, and yet that the bridge por-
tions will be as bendable as possible so that they may readily be
bent around the outer' surface of the conduit.
As shown in Fig. 2, conduit 3 is supported on the outer
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edges of flanges 7a, 7b of channel 5. Cutout 27 of each strap has
a first or bottom edge 31 extending between bridge portions 29a, 29b
adjacent stem portion 13 and a second or upper edge 33 extending be-
tween the bridge portions adjacent bend line 20. With straps lla,
llb on opposite sides of conduit 3, the bottom edges 31 of cutout 27
are shown to be substantially aligned with'one another and with the
centerline CL of conduit 3 when the conduit being clamped has an
outer diameter equal to the minimum specified diameter Dl of the
range of diameters which the clamp may accommodate. By positioning
the lower' edge 31 of the cutout adjacent the centerline of the smal-
ler size'conduit to be'clamped, the entire length of intermediate
portion 17 is constituted by the relatively flexible'bridge portions
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29a, 29b so that it may readily conform (i.e., bend) to the shape
of the conduit.
To install a clamp 1 of this invention, a conduit 3 to -
be clamped is brought into engagement with the outer edges of
channel flanges 7a, 7b and a clamp strap lla, llb of the proper
size for the nominal size of the conduit to be clamped is inserted
in slot S on opposite sides o~ the conduit. Ears 15a, 15b of the
straps are hooked on channel lips 9a, 9b and intermediate portions
17 of the straps are brought into engagement with a portion of the
outer surface of the conduit. ~olt 23 is inserted through aper-
tures 21 and is threaded into nut 25 which is held against turning
by bend line 20. Upon tightening bolt 23, skraps lla, llb are drawn
together causing their intermediate portions to con~orm to the cur-
vature o the conduit~ ~g the bolt is tightened the ~traps slide ;~
on the outer surf~ce of the conduit as the outer end portions 19
and bend lines are drawn together. This places the straps under
tension and forcibly pulls the conduit into engagement with the sup-
port channel thereby frictionally locking the conduit on the support
channel. `~
In view of the above, it will be seen that the several
objects of the invention are achieved and other advantageous results -
attained.
As various changes could be made in the above construc- -
tions without departing from the scope of the invention, it is in- ;
tended that all matter contained in the above description or shown ;
in the accompanying drawings shall be interpreted as illustrative
and not in a limiting sense.
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