Gate valve

Abstract

A packingless gate valve is disclosed which includes a housing having opposed similar housing halves with resilient sleeve units which compressibly engage each other in the valve open condition and engage opposite sides of the gate in the valve closed condition. Each sleeve unit has a plurality of compression holes extending axially and arranged at intervals relative to the circumference of the sleeve. An encircling stiffening ring of harder material is encapsulated in each sleeve so as to be positioned at the inner end of the compression holes. The compression holes may be left empty or, alternatively, may be sealed with plastic plugs, filled with closed cell foam or mechanical springs. The compression holes provide space for the displaced volume of sleeve elastomeric material to flow into during opening and closing of the gate. The gate valve construction of the present invention results in no leakage to the outside when the valve is fully open and no leakage to the outside or past the gate internally when the valve is fully closed. A lockout device of the invention has alternative positions for preventing the valve from opening or closing. In an alternative embodiment of the gate valve, the inner axial sealing end of each sleeve is located radially inwardly as compared to the location of the stiffening ring. As a further alternative, a groove is located along the radially inner surface of the sleeve in an arc of approximately 120 degrees, with the arc extending from the four o'clock to the eight o'clock position.