Occupant load

A steel-frame maintenance building with sheet-metal siding is located 300 ft (90 m) from the edge of process unit handling ethylene. The building has an occupancy load of 800 person-hours, with 20 personnel present 40 hours a week. This exceeds the company s occupancy criteria. 

A small engineering building is located 350 ft (107 m) from the process unit discussed in Example 8. It has an occupancy load of 500 person-hours, which exceeds the company s occupancy criteria. The building is constructed of unreinforced concrete and contains several windows. Earlier calculations estimated the incident side-on overpressure to be 0.5 psi at 350 ft (0.069 bar at 105 m). 

Occupancy Load (Person-hours/Week) Classification Action I... 

Occupancy load of fewer than 200 Low occupancy No action required... 

Occupancy load of between 200 and 400 Medium occupancy Consider further evaluation, unless building clearly presents no significant risks to occupants... 

Occupancy load greater than 400 High occupancy Further evaluation required... 

As discussed in Chapter 3, occupancy loads can be calculated as follows ... 

Egress models generally require a detailed plan of the layout or area considered. Additionally, the occupant load, the type of occupants, and the smoke conditions are input requirements. The models can be used to predict the egress time from the floor or deck level, stair egress time, congestion locations. 

In those cases where an engineering evaluation is used to establish life safety criteria, travel distance to an exit should at a minimum be determined by an evaluation of occupancy hazards, occupant loading, egress pathways and hazard protection/mitigation features of the warehouse building. 

It is clear that VOCs have a multitude of sources in buildings and that VOC concentrations will vary according to building characteristics (e.g. age, urban location, moisture control), occupant factors (e.g. occupancy loading, occupant-related sources, occupant... 

Exit routes must support the maximum permitted occupant load of each floor and the capacity (width) of an exit must not decrease in the direction of travel. 

If sufficient legal exits cannot be maintained during renovations or at other times, the occupancy load must be reduced or perhaps sections of the building, served by the needed exits, should be closed temporarily. At a minimum, each floor of every building with an occupancy load up to 500 persons must have at least two legal exits between 500 and 1000, three exits and above 1000, at least four exits. 

The minimum width shall be at least 44 inches for occupant loads greater than 50, or 36 inches for occupant loads of 50 or less. 

In general, it is recommended that all doors for laboratory structures should be of the side-hinged, swinging type, opening in the direction of exit travel. For doors opening onto stairways and for an occupant load of 50 or more, or for a high hazard occupancy, doors with these characteristics are required. 

The NFPA 130 provides explicit rules for determining the munber of passengers (station occupant load) who need to be evacuated from platforms in order to reach a point of safety. 

The station occupant load has been calculated referring to the passenger demand in the peak hour and is reported in the following. 

Table 1. Station occupant load in the peak hour. 

Table 2. Evacuation of platform occupant load from platform in 4 minutes or less. 

Occupant Load Occupant load is the number of people expected to be present at one time in a building (or floor). The standards set minimum occupant loads, usually expressed as square feet per person, when estimating the number of occupants. Other units are inches per person for bleachers and other bench-type seats and number of fixed seats. The standards vary with occupancy. 

Number of Exits One principle of exit design is providing at least two routes of egress from any point in a building. Certain occupancies and occupant loads require more exits. 

In life safety design one must compute the required number of exit units. The procedure involves computing the occupant load for a floor and then the number of exit units. 

Occupant load = floor area/aUowable occupant load (16-5) Number of exit units = occupant load/... 

The floor area comes from the building floor plan. Codes specify the allowable occupant load and allowable capacity per exit unit for particular occupancies. 

Are the number of exits from each floor of a building and the numb of exits from the building itself appropriate for the building occupancy load ... 

A similar approach is used to assess the number of exits available to the occupants and can also be fonnd in NFPA 101 (2012). An occnpant load is multiplied by 0.2 inches to determine how many inches of egress are required and by 0.3 inches to assess the width of stairways. Understand that doors are currently required to be a minimum of 36 inches wide in order to accommodate those occupants utilizing wheelchairs, walkers, or crutches. For example, in rooms with occupant loads of less than fifty persons, one exit door may suffice and may swing inward or against the path of egress. Where rooms are occupied by more than 50 people, two exits are required to be provided. These exits must be remote from each other, and the doors must swing outward, or in the direction of travel. 

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