CHECK VALVE Russian patent published in 2003 - IPC

FIELD: well drilling and servicing, particularly, devices for prevention of settling of cuttings above bottomhole devices, and gas and fluid outbursts through drill and casing strings. SUBSTANCE: check valve consists of hollow body accommodating conical seat, limiting lattice, shutoff unit. Core of shutoff unit has shank and conical stop surface passing into cylindrical band. Flexible conical collar with hub is secured to core and engageable with conical seat and provides for closing by funnel of passage channel formed by core in body cavity. Made in places of hub passing into funnel are external circular recess forming, together with funnel, of sealing cylinder embracing cylindrical band, and annular bore with internal grooves diverging from bore along generator of funnel internal conical surface. Collar separates passage channel of valve body into above-collar and under-collar semicavities. The latter is communicating with beyond body space. EFFECT: higher service life of check valve. 11 cl, 8 dwg