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Title:
Equalizing standing valve with hold-down
United States Patent 2994280
Inventors:
Daffin, Douglas E.
Publication Date:
08/01/1961
Assignee:
CAMCO INC
Primary Class:
Other Classes:
137/68.17, 137/454.4, 166/217, 166/322, 166/324, 166/325, 285/2
International Classes:
E21B34/14
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Foreign References:
GB331604A