The Gate Valve moves back and forth rapidly and abnormally

(2) Excess pressure. The difference between the discharge pressure and the opening pressure, usually expressed as a percentage of the opening pressure.

(3) Seat return pressure. The inlet pressure when the Gate Valve contacts the valve seat again after discharge, that is, the opening height becomes zero.

(4) Opening and closing pressure difference. The difference between the opening pressure and the seat return pressure, usually expressed as a percentage of the seat return pressure to the opening pressure. Only when the opening pressure is very low, the pressure difference between the two is used to express it.

(5) Back pressure. The pressure at the outlet of the Gate Valve.

(6) Rated discharge pressure. The upper limit of the discharge pressure specified by the standard.

(7) Sealing test pressure. The inlet pressure for the sealing test, at which the leakage rate through the sealing surface of the closing member is measured.

(8) Opening height. The actual lift of the Gate Valve from the closed position.

(9) Flow channel area. Refers to the small cross-sectional area of the flow channel between the inlet end of the Gate Valve and the sealing surface of the closing member, which is used to calculate the theoretical displacement when there is no resistance.

(10) Flow channel diameter. The diameter corresponding to the flow channel area.

(11) Curtain area. The cylindrical or conical channel area formed between the sealing surfaces when the Gate Valve is above the valve seat.

(12) Discharge area. The small cross-sectional area of the fluid channel when the valve is discharging. For a fully open Gate Valve, the discharge area is equal to the flow channel area; for a micro-open Gate Valve, the discharge area is equal to the curtain area.

(13) Theoretical displacement. It is the calculated displacement of an ideal nozzle with a flow channel cross-sectional area equal to the Gate Valve flow channel area.

(14) Displacement coefficient. The ratio of actual displacement to theoretical displacement.

(15) Rated displacement coefficient. The product of the displacement coefficient and the reduction coefficient (taken as 0.9).

(16) Rated displacement. Refers to the part of the actual displacement that is allowed to be used as the applicable benchmark for Universal Valve.

(17) Equivalent calculated displacement. Refers to the calculated displacement of the Gate Valve when the pressure, temperature, medium properties and other conditions are the same as the applicable conditions of the rated displacement.

(18) Frequency jump. The Gate Valve moves back and forth rapidly and abnormally, and the Gate Valve contacts the valve seat during the movement.