The unit is constructed of lightweight aluminum. It can be opened and closed by one man using the convenient lifting handles. The 42-inch size has a 40-lb.lift weight. The roof manhole cover comes
complete with a self-locking foot pedal, spring loaded open cover latch mechanism and a manual safety pin to
prevent accidental closure of the cover.
When pressurized, the unit is ideal for use on vessels that must hold a positive head pressure. The cover is held in place by eight to ten hinged wing nuts depending on the diameter of the cover. The wing nuts
can be opened or sealed tightly against pressure by one person, in less than five minutes without the use of any special tools or devices.