Differential pressure control pneumatic valve structure itself

here to ZY - C type differential pressure control pneumatic valve itself as an example, introduces its working principle of differential pressure control pneumatic valve. Spring, pressure sensitive film with the pneumatic valve stem consolidation, pressure pipe through guide will export the upper part of the seal chamber pressure P import pressure sensitive membrane, lower pressure sensitive film for inlet pressure P. According to the P - P value Δ Ps ( Hereinafter referred to as the set pressure difference) To determine the spring precompression, even if the spring tension and setting the differential of spring force is equal under the condition of pressure sensitive film. And according to the pneumatic valve plug is far less than the spring schedule beforehand principles of selection of compression spring. This makes any opening balance in the pneumatic valve, pneumatic valve's inlet and outlet pressure differential Δ P and setting the differential Δ Ps approximately equal. Strictly speaking, the opening is different, equilibrium Δ P is not equal. Obviously, with the increase of the opening, equilibrium Δ P is enlarged. But through the selection of spring, can completely within the whole trip in pneumatic valve plug, the equilibrium state of Δ P relative to Δ Ps deviation control in a certain range ( For example, %) Within. Self-reliance type differential pressure control pneumatic valve itself in the system show the work can be divided into two situations: (1) the current status to closed. If the pneumatic valve differential pressure Δ P is less than the set pressure difference before and after Δ Ps, continued to shut down, then is a dynamic valve clearance expired. If Δ P is greater than the Δ Ps, the pressure sensitive film to overcome the spring tension, drive, pneumatic valve plug up pneumatic valve opens; Differential pressure at the inlet and outlet of the equilibrium state, approximate Δ P back to set the differential Δ Ps. (2) the current status to open. If the system stable running, inlet and outlet pressure differential Δ P approximation for setting pressure difference. If the change of the system working condition, make Δ P increases, the pneumatic valves open big, traffic increase, Balance, Δ P approximate back to Δ Ps. Pneumatic valve for the biggest opening, Δ P > Δ Ps case, pneumatic valve no longer have the ability to control pressure difference. If due to the change of system operating mode, the inlet and outlet pressure differential Δ P < Δ Ps, the small pneumatic valve, flow decreases, and reaches an equilibrium state, Δ P and approximate rise to Δ Ps. Pneumatic valve closing, finally appears Δ P < Δ Ps, no longer have the ability to control pressure difference, and become a dynamic valve clearance expired. Their self-reliance type differential pressure control, in short, pneumatic valve in the closed state, Δ P must be greater than Δ Ps can open; In open state, can automatically adjust the opening, maintaining basic constant pressure difference before and after pneumatic valves.