| 摘要 |
<p>A positive displacement pump includes a relief valve comprising an valve seat, a needle within the valve seat, a spring forcing the needle within the valve seat, a set screw pressing the spring against the needle and a spacer for mounting the set screw to the housing of the positive displacement pump. The relief passages are formed at the intersection of the valve sleeve and the piston. The valve seat threadably connects within the relief valve passageway to prevent the erosion of the passageway. The valve seat may be constructed from a plastic, hard rubber, or metal material and include a rubberized seal secured at one end of the valve seat. When the valve seat erodes to a point where it provides an insufficient seat for the needle, it is removed from within the relief valve passageway and replaced with a similar valve seat. By protecting the relief valve passageway from erosion by using an inexpensive, removable, and disposable valve seat, costly disposal or machining of the housing of the positive displacement pump is avoided.</p> |
