Double acting means the door swings in AND out...versus in OR out for a standard (single acting) door. You'll see this in a lot of restaurants going into the kitchen.
This can be a single door or a pair of doors. You'll need a special frame for this application called a Cased Open frame. This frame has no stop (like a standard door frame has) so the door can swing both ways.
Double egress is always a pair of doors (never a single door) and allows each door to swing in the opposite direction.
You will usually see these in corridors and they are frequently used in hospital corridors. These doors provide quick exit/entry from either direction of traffic flow. You'll also need a special frame for this application as you can see in the picture above.
Jan 10: Lead Lined doors & frames
Usually you will use a wood door but you can get a lead lined hollow metal door. 1/16" thick lead is "standard" which is 2 pieces of 1/32" lead either side of the wood door core. 1/8" ( 2pcs. 1/16") is also used quite often. Common options range from 1/32" to 1/8".
Doors will remain 1 3/4" thick with up to 1/8" lead in them. Over that and the door thickness starts to increase so make sure you get a special frame for a non standard thickness door in this case. You can go as thick as 3/8" lead but lead this thick will be put in the center of the door as 1 piece. Lead in hollow metal doors is most always put in the center of the door (no matter the thickness) with steel stiffeners holding it in place.
Use a hollow metal frame with a jamb depth of at least 6" (5" throat). A standard stud wall has 3 5/8" studs with 5/8" drywall each side giving you 4 7/8" but you will also have 1/8" lead in the wall for a total of 5".
It's a good idea to use pivots instead of hinges due to the weight of the door. The Rixson L147 set (includes top & bottom pivot) along with an ML19 intermediate pivot is a good example. Use 2 intermediate pivots if the door is over 7'0".
You'll want a lead lined lock as well. The Schlage L series mortise lock, Corbin Russwin CL3300 series cylindrical lock, Best 8K or 9K cylindrical locks, as well as many others all have this option.
If you use a closer you'll want a lead lined full cover with it and use a lead lined astragal at pairs of doors. Lead thresholds or shielded door sweeps are required at the bottom of the door when a gap is 1 inch or more between the bottom of the door and the floor.
Now if you are renovating a hospital or a doctor's office you know what to look for on the x-ray room openings!
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