Plastic lined diaphragm valve

Synthetic resinous thermoplastic lines in a diaphragm valve are stabilized against movement by extending the lines into recesses in the bonnet receiving face of the valve body.

Plastic lined diaphragm valves have found wide use in industry. Such valves 
comprise two major portions: (1) a bonnet assembly which carries the 
diaphragm and (2) a body portion having a weir disposed therein. Such 
valves are generally constructed in such a manner that it is only 
necessary to provide a plastic lining in the body portion. Such linings 
are applied by a molding process wherein the heat plastified material is 
forced into a space within the body, defined by the body and a removable 
mandrel assembly. When such plastic lined valves are employed in high 
temperature service, occasionally shrinking of the lining occurs, 
particularly in the region of the weir, in such a manner that contact of 
the liner with the diaphragm is reduced. By the term "high temperature" is 
meant a temperature at which deformation of the liner can occur without 
applying external force. 
It would be desirable if there were available an improved plastic lined 
diaphragm valve. 
It would also be desirable if where were available an improved diaphragm 
valve having a reduced tendency for deformation of a plastic liner therein 
at higher temperatures. 
It would also be desirable if such an improved valve were readily and 
easily constructed. 
These benefits and other advantages in accordance with the present 
invention are achieved in an improved plastic lined diaphragm valve, the 
diaphragm valve comprising a body portion, the body portion having a first 
end and a second end, the passageway extending from said first end to said 
second end, the body portion defining a weir, the weir extending in a 
direction generally perpendicular to a longitudinal axis of the 
passageway, the body defining an intermediate opening at a location 
generally opposite the weir; about the opening opposite the weir a bonnet 
receiving surface, the bonnet receiving surface being of annular 
configuration, a plastic lining disposed within the body, the lining 
extending out of said body and covering at least a portion of the bonnet 
receiving surface, a bonnet assembly affixed to the bonnet receiving 
surface; the improvement which comprises the bonnet receiving surface of 
the body defining at least a first and second recess, said first and 
second recesses being generally diametrically opposed, and generally 
adjacent the weir with the further limitation that the plastic lining 
extends into said recesses.

In FIG. 1 there is schematically depicted a diaphragm valve in accordance 
with the present invention generally designated by the reference numeral 
10. The valve 10 comprises a valve body 11 having affixed thereto a bonnet 
assembly 12 having a movable diaphragm 13. The body 11 has a first end 14 
and a second end 15. The body 11 defines a passageway 16 extending from 
the first end 14 to the second end 15. Disposed within the passageway 16 
is a weir 17. The passageway 16 is in full communication with a bonnet 
receiving surface 18. The surface 18 is of generally annular 
configuration. The valve body 11 has disposed therein a plastic or 
synthetic resinous thermoplastic lining 21. The lining 21 extends to 
partially cover the bonnet receiving surface 18 and extends radially 
outwardly at first end 14 and second end 15. 
In FIG. 2 there is depicted a top view of a valve body 11a prior to lining. 
The valve body 11a has a bonnet receiving surface generally designated by 
the reference numeral 18a. The bonnet receiving surface has a generally 
annular configuration and has disposed therein threaded apertures 23 which 
receive bolts to affix the bonnet assembly thereto. The body 11a has a 
weir 17a extending generally transverse. The body receiving surface 18a 
defines a first generally elongate recess 25 and a second elongate recess 
26. The elongate recesses extend generally perpendicular to the weir and 
generally parallel to a passageway through the valve body 11a. 
In FIG. 3 there is depicted a cross section view of the valve body 11a 
taken along the line 3--3 of FIG. 2, depicting the configuration of the 
recesses 25 and 26 relative to the weir 17a. The recesses 25 and 26 have 
been formed by milling utilizing an end mill in such a manner that a 
projection of the recesses in a direction away from the weir and the 
surface 18 would be divergent. 
In FIG. 4 there is depicted a fractional view of a body such as the body 
11a depicting the manner in which a plastic liner 21a is molded into a 
recess such as the recess 26. 
In FIG. 5 there is depicted a fractional view of a bonnet receiving surface 
18b having formed therein a plurality of recesses 29. 
Valves in accordance with the present invention are readily prepared by 
conventional plastic lined techniques. The recesses in the bonnet 
receiving face can be formed by a variety of means. For example, the 
configuration of FIG. 5 is readily prepared by drilling a plurality of 
shallow, generally cylindrical holes in the bonnet receiving face, 
generally adjacent the weir. The improvement as depicted in FIGS. 2, 3 and 
4 is readily obtained by milling recesses 25 and 26 utilizing an end mill. 
Such recesses can be formed in the bonnet receiving face utilizing a 
milling cutter which is disposed vertically or at an angle to the bonnet 
receiving face. Plastic lined valves in accordance with the present 
invention can utilize a variety of plastics, such as polypropylene, 
vinylidene chloride polymers, fluorocarbon polymers and the like. 
Comparative tests indicate that valves in accordance with the present 
invention at elevated temperatures exhibit substantially increased 
dimensional stability of the liner in the region of the weir when operated 
at higher temperatures. 
As is apparent from the foregoing specification, the present invention is 
susceptible of being embodied with various alterations and modifications 
which may differ particularly from those that have been described in the 
preceding specification and description. For this reason, it is to be 
fully understood that all of the foregoing is intended to be merely 
illustrative and is not to be construed or interpreted as being 
restrictive or otherwise limiting of the present invention, excepting as 
it is set forth and defined in the hereto-appended claims.