Remarkable Knife Gate Valves

Original designs of knife gate valves can be traced back to tools
which consisted of a gate, parallel sides and a pressure that was placed
into a main pipe line. The purpose of these valves was to shut off the
flow of liquids by use of the pressure on the upstream side of the
valve. Fluid pressure was vital in order to create the required force in
which to seal the valve. Various methods had been developed in the past
to achieve this, in which the gate would be mechanically pushed against
both faces to create a tight seal. This then resulted in the valve
action being independent of the pipe line pressure.

During the mid 1860’s, a Mr. Chapman was chopping wood at his home.
His attention was soon drawn to the head of his axe, in particular, its
shape. This humble beginning soon evolved into the solid wedge gate
valve which is used throughout various industries in modern today. In
the following years, many attempts were made to combine the advantages
of the solid wedge and double disk gate valve together. Eventually, a
proven design emerged, which became known as the ‘split wedge’. The
advantage of the split wedge design is that although more costly, it has
the advantage of being self adaptable to the limited amounts of
distortion which is created by strain in the pipe line. In addition, it
provides a unique advantage for special installations where it is used
to seal a space between the seals with inert gases or steam.
In recent times, another variation has entered the industry
associated with knife gate valves, referred to as the ‘flexible wedge’.
In this design, the wedge is one piece, but possesses a cut out section
between the two seats. This is completed in such a way to provide a
minor degree of flexibility and gives the user the advantage of
relieving excess stress from the valve spindle which is required to
close the gate valve when subjected to extreme high temperatures. In
this connection, it is of interest to note that the field of atomic
energy has reverted to the 1920’s era, in the utilization of a valve
construction with parallel seats. Added to this, is the reliance on the
pressure within the pipe line to keep the valve tight. This has been
made possible, as although pressures are high when involved with
pressurized water reactors, the actual temperature is less than 600°F.
In the ever developing modern market of today, the various models of
valves such as knife gate valves, are manufactured from strictly
controlled materials which for USA knife gate manufacturers, must meet
specifications set by the American Standards Association (B16). The
dimensions of the valves have been standardized in order that in usual
practice, they may be interchanged between different manufacturers. When
methods of operating gate valves are being considered, the hand-wheel
is usually on the list. This is mainly due to the fact of the simple
operation of opening and closing. However, it must now be taken into
account that the sizes of gate valves are increasing, together with
pressures and temperatures. This has resulted in the strength required
to operate them, exceeding the capabilities of one work person. This is
in many ways a tribute to the manufacturers of knife gate valves and
valves in general, as these have proven their development ability in
meeting and even excelling in providing the equipment to satisfy users’
ever increasing requirements.
The development of knife gate valves and their related products is an
example of innovation and commitment to customer service on behalf of
their manufacturers. The designs of these valves and the materials used
in order to manufacture them, is keeping pace with the sophisticated
demands of global trade. The degree of expertise required within the
design and manufacturing of high quality and high performance valves
must be recognized as being highly competitive. Each valve, no matter
what its intended use may be, in every situation will be judged on merit
by its user in regards to the performance and efficiency it provides.
From the original1gatevalve
.