Note: Descriptions are shown in the official language in which they were submitted.
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PING-FREE WATER HAMMER ARRESTER
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to water hammer arresters; i.e. to
devices for preventing the development of water hammer in
conduits conveying water under pressure and under conditions
of interrupted flow.
2. Description of the Prior Art
The familiar phenomenom of water hammer is caused by the
development of hydraulic shock waves generated by the sudden
stopping of fluid flow within the confines of a conduit system
carrying water under pressure. This condition results from
the rapid closing of positive valves incorporated within the
system. In addition to the production of unpleasant noise
effects, fluid hammer if allowed to persist for any length of
time, will result in broken conduits and damage to other
components of the conduit system.
Various types of fluid hammer arresters are known to the
prior art. The most commonly employed of such devices
includes expandable bellows or diaphragms which absorb the
shock. These are so subject to failure that their service
life is short.
Another type of fluid hammer arrester involves the
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application of a piston working against the pressure developed
by a compressed gas chamber. Such a device is disclosed in
Perrott et al, U.S. Patent No. 3,633,627. Although widely and
successfully used, water hammer arresters of the Perrott et al
class are characterized in use by a noise generating problem.
When subjected to rapid and substantial pressure drop, the
metallic piston with which they are provided occasionally
forcibly contacts an opposed metallic wall. This causes the
production of an unpleasant metallic sound, or "ping". The
arresters accordingly defeat their own purpose in that they
themselves become a sound-producing instrument.
It is the general purpose of the present invention to
provide a water hammer arrester which overcomes this problem,
and which is ping-free.
THE PRESENT INVENTION
In accordance with the present invention, a ping-free
water hammer arrester is provided which comprises a hollow
cylindrical body closed at one end and open at the other. A
piston is freely slidable within the body and forms in the
closed end thereof a hermatically sealed gas chamber.
A hollow, cylindrical connector ("nipple"), open at both
ends, is secured to the open end of the body for connection to
a conduit conveying fluid under pressure. This places the
body in open communication with the conduit, and the fluid in
the conduit in pressure contact with the piston.
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Reciprocation of the piston with fluctuation in fluid pressure
between advanced and retracted positions accordingly occurs.
An abutment is provided on the connector. It is
positioned opposite the piston and in its path of travel.
A shock absorbing bumper is mounted on mounting means
which positions it between the piston and the abutment. The
bumper is of resilient material and absorbs the shock of the
piston if it should slam into the abutment. The noise problem
accordingly is eliminated.
THE DRAWINGS
In the drawings:
Fig. 1 is a fragmentary view in side elevation of a
piping system including the herein described water hammer
arrester.
Fig. 2 is a longitudinal sectional view of the arrester
in its assembled condition.
Fig. 3 is an exploded top perspective view of the
arrester.
DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
The presently described water hammer arrester is
indicated generally at 10, Fig. 1. It is adaptable for
installation in fluid conveying systems wherever there is a
likelihood of the development of fluid hammer. Such a
situation is present in the illustrated example where there is
fluid flow through a conduit system 12 including a valve 14.
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As is well known, closing the valve suddenly and thusarresting the flow of fluid through the conduit system may
result in setting up water hammer conditions.
In general, the water hammer arrester should be placed as
near the source of shock as possible. It also should be
installed in such a manner that there is an unobstructed shock
path to the arrester.
Thus, in the illustration of Fig. 1, the arrester may be
included in the conduit system simply by inserting a T 16 to
which the arrester 10 is coupled.
The construction of the arrester and its manner of
operation are shown in detail in Figs. 2 and 3.
The arrester includes a hollow cylindrical body 20 which
is closed at one end 22. It may be made of brass or other
suitable metal.
A piston indicated generally at 24 is freely slidable
within the cylindrical body. Its peripheral surface is formed
with annular grooves 28 and intervening lands 30. Sealing
rings (O-rings) 32 seat in the grooves. They may be made of
natural or artificial rubber, plastic or other suitable
material.
A connector indicated generally at 34 by means of which
the arrester is coupled to the fluid conducting system is
mounted by soldering or other suitable method on the open end
Of cylinder 20.
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The connector has a cylindrical body or cap segment 36
which fits over the open end of cylindrical body 20 and in
sealed relation thereto, as by means of soldering. A threaded
attaching segment 38 facilitates its application to the piping
components of the system.
The foregoing arrangement places cylinder 20 in open
communication with the conduit components of the system. It
also places the fluid in the conduit in pressure contact with
the piston, whereby to reciprocate the piston with
fluctuations in water pressure between a retracted position in
which the piston is housed within the cylinder, and an
advanced position in which it can progress into contact with
connector 34. Since both of these components may be made of
metal, there may result the "ping" which it is the purpose of
this invention to prevent.
To this end, there is provided an abutment on connector
34. This is positioned opposite the piston and in its path of
travel. In the illustrated form of the invention, the
abutment comprises inwardly tapered (with reference to the
direction of travel of the piston) abutment surface 40. This
preferably is contoured in the geometry of a truncated cone,
as is evident from Fig. 2.
Shock-absorbing bumper means are positioned between
piston 24 and abutment surface 40. Although the bumper means
may be positioned on either one of these two components, it
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preferably is mounted on piston 24.
To this end the forward (with reference to the direction
of travel) margin of the piston is provided with an annular
marginal recess 42. This recess seats a resilient bumper
ring, such as O-ring 44. As in the case of O-rings 32, O-ring
44 may be fabricated from natural or synthetic rubber, or a
suitable resilient plastic.
Adhesive 46 is interposed between the bumper ring and the
recess in which it is seated to insure against displacement
during operation of the assembly.
OPERATION
In the operation of the herein described ping-free water
hammer arrester, the unit is inserted in the water conduit
system in the manner illustrated in Fig. 1. As fluctuations
in house line water pressure occur, piston 24 will reciprocate
inside cylinder 20. This absorbs the pressure shocks and
prevents water hammer.
In the event that metallic piston 24 should slam against
metallic connector 34 during operation of the device, the
collision is prevented and the shock absorbed, by virtue of
bumper ring 44 of the piston colliding with abutment surface
40 of the connector.
Both water hammer noise and arrester ping thus are
eliminated in a simple, integral device.
It is to be understood that the form of my invention
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herein shown and described is to be taken as a preferred
example of the same and that various changes in the shape,
size and arrangement of parts may be resorted to without
departing from the spirit of my invention or the scope of the
subjoined claims.
I claim:
