| 摘要 |
<p>Valve boxes (10) of this invention comprise a housing (12) including an inner chamber that extends axially through the housing from a housing base (16). The housing chamber includes a diameter that is defined by a housing sidewall surface (18,20,22,14) that extends outwardly from the base (16), forming a chamber opening. The chamber opening includes a seal surface that is positioned radially inwardly towards the chamber. The valve box further includes a lid (14) that is positioned over the housing chamber opening. The lid includes a concave center section (43) and a seal surface disposed radially therearound. The lid seal surface is positioned radially towards the chamber, and is placed opposite the chamber opening seal surface. An annular seal is interposed between the housing chamber and lid seal surfaces. The chamber and lid seal surfaces are configured generally perpendicular to the chamber opening, such that internal pressure within the chamber causes the concave center portion to impose a radially outwardly directed pressure onto the lid, thereby further compressing the annular seal to ensure a leak-tight seal. <IMAGE></p> |
