GATE VALVE

LVF Gate Valve

A valve which provides a straight-through passage for the flow of fluid. The body ends are in line and the gate is moved between the body seats by a stem whose axis is usually at right angles to that of the body ends. Gate valves may be:

a. Inside screw

In which the actuating thread of the stem is contained inside the valve. This may take two forms:

 (i)           

Inside screw, rising stem. Where the handwheel is attached to the stem and rises with it when the valve is opened.

(ii)          

Inside screw, non-rising stem. Where handwheel is attached to a non-rising stem, the gate rising on the stem when the valve is opened.

 b. Outside screw

In which the actuating thread of the stem is exterior to the bon¬net. This may take two forms:

 (i)           

Outside screw, stem rising with handwheel. Where the hand-wheel is attached to the stem and rises with it when the valve is opened.

 (ii)          

Outside screw, stem rising through handwheel. Where the hanwheel is attached to a yoke sleeve which revolves in the yoke and through which the stem rises when the valve is opened.

TYPES OF GATE VALVE

Wedge gate valve           

A valve in which closure is effected by the wedge action between the wedge gate and the body seats. Wedge gate valves may take the following forms:

 a. Solid wedge  

In which the wedge gate is in one piece, either solid, cored or flexible.

 b. Split wedge  

In which the wedge gate is in two pieces.

Gate valve         

A valve in which closure is effec¬ted by a sliding action between the gate and body seat or seats. Gate valves may take the fol¬lowing forms:

a. A two piece gate with spreading mechanism

A valve in which the gate consists of two pieces which are forced apart by a spreading mechanism at the point of closure against both parallel body seats, thus ensuring an effective sealing of the valve.b. A two piece gate.A valve in which the gate consists of two pieces without spreading mechanism, which slide between parallel body seats, effective closure being obtained by the pressure of the fluid forcing the down stream piece of the gate face against its mating body seat

b. A two piece gate

A valve in which the gate consists of two pieces without spreading mechanism, which slide between parallel body seats, effective closure being obtained by the pressure of the fluid forcing the down stream piece of the gate face against its mating body seat.