It is common practice to employ disc or poppet valves for the above-described application, and several valve discs may be mounted on a common stem. The known valves quickly open the aperture in a valve seat when moving away from the same, and suddenly block liquid flow as they engage the valve seat. Cast Steel ValvesThe inertia of the body of liquid whose velocity is changed abruptly by opening or closing of the valve exerts a sudden stress or shock on the elements of the hydraulic system causing noise and potentially mechanical damage.

The object of the invention is the provision of a valve which may control the flow of large bodies of liquid without causing significant mechanical shock or noise. In one of its basic aspects, the invention provides a housing defining a cavity and formed with a plurality of ports leading outward of the cavity. API Cast Steel ValvesFirst and second valve seat members are arranged at first and second ports of the housing and are formed with apertures of predetermined cross section A valve member in the cavity may be moved by a drive arrangement between first and second operating positions in which the valve member sealingly engages the valve seat members respectively and seals the aperture of the engaged valve seat member. A throttling member is mounted on the valve member and projects from the same into the aperture of the engaged first valve seat member when the valve member is in its first operating position. The throttling member has a smaller cross section than the aperture. MUD VALVESIn its more specific aspects, the valve has a casing consisting mainly of a plurality of sections juxtaposed in a row. Each section defines a cavity therein and is formed with two ports aligned in the direction of the row with the ports of the other sections. A valve seat member is sealingly interposed between each pair of juxtaposed sections and formed with an aperture aligned with the ports in the afore-mentioned direction, whereby two valve seat members are associated with each section. A drive rod passes through the aligned ports and apertures and carries at least two valve disc assemblies. Each valve disc assembly is received in the cavity of a respective casing section for movement with the drive rod between respective positions of sealing engagement with the two valve seat members associated with the receiving section. Each assembly includes two throttling portions received in the apertures of the two valve seat members in the two positions of the valve disc assembly respectively. The cross section of each throttling portion is smaller than the cross section of the receiving aperture transverse to the direction of drive rod movement.

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2011-12-09

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