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NTIS 바로가기국가/구분 | United States(US) Patent 등록 |
---|---|
국제특허분류(IPC7판) |
|
출원번호 | US-0844814 (1992-03-02) |
발명자 / 주소 |
|
인용정보 | 피인용 횟수 : 16 인용 특허 : 0 |
A rotationally operated back pressure valve includes a flapper valve with a sliding stinger tube located thereabove in a housing. An operating mandrel has a lower end portion received in a bore of the housing and the operating mandrel extends upward out of the upper end of the housing. The operating
A rotationally operated back pressure valve apparatus for use in a well, comprising: a housing having an upper end and a lower end and having a housing bore defined therethrough from said lower end to said upper end; a flapper valve disposed in said housing, said flapper valve having a closed positi
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