Section 106.—DOORS, MANHOLES AND COVERS.
(See also [p. 242].)
[2582]. Screw plug, with two lugs to screw it up by a plain bar placed between them.
[2583]. New form of manhole door.
[2584]. Screw fixing for a plug, door, or valve, quickly released or secured.
[2585]. Hollow plug, with square recess for a key or spanner. Flush plug.
[2586]. Soot door.
[2587]. Funnel plug, for filling oil reservoirs, &c.
[2588]. Wrought iron or steel manhole door, dished.
[2589]. Oven door, lifts out of the catch by leaving sufficient play in the top hinge.
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[2590]. Soot door.
[2591]. Soot door in section, opened by pulling outwards and downwards; the hook at top prevents it falling out.
[2592]. Screw cap or cover.
[2593]. Revolving door.
[2594]. Sliding door for furnaces, &c. The weight of door may be relieved by rollers at top, as shown.
[2595]. Door or manhole held up by two wedges.
S traps. D traps. These are divided chambers, or bent portions of pipes, designed to always contain a well of water so as to cut off any currents of air or gases that would otherwise pass along the pipes.
Street manholes and lampholes are round, rectangular, or oval covers, strongly made to carry street traffic, and fitted in strong cast-iron frames, so as to be easily removable, and yet practically air-tight. Those fitted over sewer manholes are frequently provided with charcoal filters to arrest foul gases.