Removable tank portal cover

Abstract

A hatch cover includes spring-loaded exhaust and suction valves to regulate internal tank pressure with respect to outside pressure. The valves are disposed in a ring housing. The cover further includes a spring-loaded locking bolt configured to engage the hatch base and thereby provide a retaining force between the housing and the hatch base. The exhaust-valve springs may be selectively preloaded to establish a target exhaust pressure. The locking-bolt spring may be selectively disengaged or overcome to release engagement of the bolt from the hatch base.

The invention claimed is: 
     
         1 . A hatch cover comprising:
 (a) a substantially cylindrical housing comprising:
 (i) a first sealing surface, 
 (ii) a radial axis; 
   (b) a pressure assembly comprising:
 (i) an exhaust valve having an exhaust-valve spring, an exhaust-valve plate having second and third sealing surfaces, and an exhaust-valve-spring loader, and 
 (ii) a suction valve having a suction-valve spring, a suction-valve plate having a fourth sealing surface, and a suction-valve-spring loader, 
 (iii) wherein the exhaust-valve spring is positioned to provide a pushing force between the exhaust-valve-spring loader and the exhaust-valve plate, 
 (iv) wherein the suction-valve spring is positioned to provide a pulling force between the suction-valve-spring loader and the suction-valve plate, 
 (v) wherein the housing and exhaust-valve plate are configured to provide a first interface between the first sealing surface and the second sealing surface, 
 (vi) wherein the exhaust-valve plate and the suction-valve plate are configured to provide a second interface between the third sealing surface and the fourth sealing surface; and 
   (c) a locking assembly comprising:
 (i) a bolt, and 
 (ii) a bolt-loading spring; 
 (iii) wherein the bolt-loading spring is positioned to provide a pushing force on the bolt directed along the radial axis. 
   
     
     
         2 . The hatch cover of  claim 1  further comprising a means for selectively reducing the pushing force on the bolt. 
     
     
         3 . The hatch cover of  claim 1  wherein the bolt includes a first end configured to engage a hatch base and a second end configured as a first member of a first sliding joint and wherein the bolt-loading spring includes a first post-engaging end and a second post-engaging end, the cover further comprising:
 (a) a track ring comprising:
 (i) a first spring-retaining post engaged with the first post-engaging end of the bolt-loading spring, and 
 (ii) a second member of the first sliding joint engaged with the first member to form the first sliding joint; 
 
 (b) a second spring-retaining post connected to the housing and engaged with the second post-engaging end of the bolt-loading spring; and 
 (c) a channel ring comprising a channel directed along the radial axis and within which the bolt is positioned; 
 (d) wherein the track ring is circumferentially nested within the channel ring; 
 (e) wherein the first sliding joint has a first joint position placing the bolt at a first point along the radial axis and a second joint position placing the bolt at a second point along the radial axis; 
 (f) wherein the bolt-loading spring provides a biasing force pushing the bolt toward the second joint position; 
 (g) wherein the first joint position corresponds to a first rotational position of the track ring relative to the channel ring; and 
 (h) where the second joint position corresponds to a second rotational position of the track ring relative to the channel ring. 
 
     
     
         4 . The hatch cover of  claim 3  wherein the channel ring is connected to the housing. 
     
     
         5 . The hatch cover of  claim 3  wherein the channel ring is integral with the housing. 
     
     
         6 . The hatch cover of  claim 3  wherein the track ring is joined to the channel ring through a second sliding joint configured to enable rotational motion between the track ring and channel ring. 
     
     
         7 . The hatch cover of  claim 6  wherein the track ring provides a circumferential groove as a slide guide. 
     
     
         8 . The hatch cover of  claim 1  further comprising a means for selectively preloading the exhaust-valve spring to control the pushing force between the exhaust-valve-spring loader and the exhaust-valve plate. 
     
     
         9 . The hatch cover of  claim 1  further comprising a valve-assembly retaining ring, wherein the exhaust-valve-spring loader includes a spring-loader ring threadedly engaged within the valve-assembly retaining ring and wherein rotation of the valve-assembly retaining ring relative to the spring-loader ring varies preloading of the exhaust-valve spring. 
     
     
         10 . The hatch cover of  claim 9  wherein the valve-assembly retaining ring is connected to the housing via a third sliding joint. 
     
     
         11 . The hatch cover of  claim 10  wherein the valve-assembly retaining ring provides a circumferential groove as a slide guide. 
     
     
         12 . The hatch cover of  claim 10  further comprising a scale reflecting a rotational position of the valve-assembly retaining ring relative to the spring-loader ring. 
     
     
         13 . The hatch cover of  claim 12  wherein the scale is calibrated to the force provided by the exhaust-valve spring to the exhaust-valve plate. 
     
     
         14 . The hatch cover of  claim 12  wherein the scale reflects an operational exhaust pressure. 
     
     
         15 . The hatch cover of  claim 3  further comprising a valve-assembly retaining ring, wherein the exhaust-valve-spring loader includes a spring-loader ring threadedly engaged within the valve-assembly retaining ring and wherein rotation of the valve-assembly retaining ring relative to the spring-loader ring varies preloading of the exhaust-valve spring. 
     
     
         16 . The hatch cover of  claim 3  wherein the housing is an assembly of a bottom component, a top component, and the channel ring, and wherein the bottom component includes the first sealing surface. 
     
     
         17 . The hatch cover of  claim 15  wherein the housing is an assembly of a bottom component, a top component, and the channel ring, and wherein the bottom component includes the first sealing surface.