Expansion and Contraction

To provide for expansion and contraction, expansion joints should be incorporated in pipelines. Such joinst should be spaced not more than 50 ft apart in hot-water pipe. While special fittings are available for the purpose, flexible connection are a coomon means of providing for expansion. Frequently, such connection consist of a simple U bend or a spiral coil, which permits springlike absorption of pipe movements.

Water Hammer

This is caused by pressures developing during sudden changes in water velocity or sudden stoppage of flow. The result is a banging sound or vibration of the piping system. It frequently results from rapid closing of valves, but it also may be produced by other means, such as displacing air from a closed tank or pipe from the top.

Water Traps

Separate traps are required for most fixtures not fitted with an integral trap. The trap should be installed as close as possible to the unit served. More than one fixture may be connected to a trap if certain code regulations are observed. For specific requirements, refer to the governing code.

A water seal of at least 2 in, and not more than 4 in, is generally required in most traps. Traps exposed to freezing should be suitably protected to prevent ice formation in the trap body. Clean outs of suitable size are required on all traps except those made integral with the fixture or those having a portion which is easily removed for cleaning of the interior body. Most codes prohibit use of traps in which a moving pasts is needed to from the seal. Doble trapping is also usually prohibited

Air Gaps

These should be provided to prevent backflow of wastewater into the water supply. At plumbing fixtures, an air gap must be provided between the fixture water-supply outlet and the flood-level rim of the receptacle. Building codes usually require a minimum gap of 1 to 2 in for outlets not affected by a nearby wall and from 1 ½ to 3 in for outlets close to a wall.

In addition to the usual drain at the lowest point, receptacles generally are provided with a drain at the flood-level rim to prevent water from overlaping. The overflow should dischange into the wastewater system on the fixture side of the trap.

Exercise 6

1.    Ramps

When space permits, a sloping surface, or ramp, can be used to connect different levels or floors. As a mean of saving space in some garages, every floor serves as a ramp. Each floor is split longitudinally, each section sloping gradually in opposite directions to meet the next level above and below.

Ramps are especially useful when large numbers of people or vehicles have to be moved from floor to floor. So they are frequently adopted for public buildings, such as railroad stations, stadium, and exhibition halls. And they are either legally required or highly desirable for all buildings, especially to acoommodate person in wheelchairs. In all cases, ramps should be constructed with a nonslip surface.

Ramps have been built with slopes up to 15% (15 ft in 100 ft ), but 8% is a preferred maximum. Some idea of the space required for a ramp may be obtained from the following. With the 8% maximum slope and a story height of, say 8 ft, a ramp connecting two floors is 100 ft long. The ramp need not be straight for the whole distance, however. It can be curved, zigzagged or spiralled. Level landings, with a lenght of at least 44 in the direction of travel, should be provided at door openings and where ramps change slope or direction abruply. Ramps and landings should be designed for a live load of at least 100 lb / ft². Railings should be designed for a load of 200 lb applied downward or horizontally at any point of the handrail or for a horizontal thrust of 50 lb/ft at top of rail. Guards higher than the minimum required guard height of 42 in should be designed for 50lb/ft applied 42 in above the floor.

2.    Type of Stairs

Generally stairs are of the following types : straight, circular, curved, or spiral,  a combination.

Straight stairs are stairs along which there is no change in direction on any flight between two succesive floors. There are several possible arrangements of straight stairs. For example, they may be arranged in a straight run, with a single flight between floors, or a series of flights without change in direction. Also, straight stairs may permit a change in direction at an immediate landing. When the stairs require a complete reversal of direction, they are called parallel stairs. When successive flights are at an angle to each other, usually 90⁰, they are called angle stairs. In addition, straight stairs may be classified as scissors stairs whe they composite sides of a fire-resistive wall.

Circular stairs when viewed from above appear to follow a circle with a single center of curvature and large radius.

Curved stairs when viewed from above appear to follow a curve with two or more centers of curvate, such as an ellipse.

Spiral stairs are similar to circular stairs except that the radius of curvature is small and the stairs may be supported by a center post. Overall diameter of such.

Stair Components

·         Flight. A series of steps extending from floor to floor, or from a floor to an intermediate landing or platform.

·         Guard. Protective vertical barrier along edges of stairways, balconist, and floor openings.

·         Landings (platform). Used where turns are necesary or to break up long climbs. Landings should be level, as wide as the stairs, and at least 44 in long in the direction of travel.

·         Step. Combination of a riser and the tread immedietly above.

·         Rise. Distance from floor to floor.

·         Run. Total lenght of stairs in a horizontal plane, including landings.

·         Riser. Vertical face of a step. Its width is usually taken as the horizontal distance between risers.

·         Nosing, projection of a tread beyond the rises below.

·         Soffit. Underside of a stair.

·         Header. Horizontal structural member supporting stair stringers or landings.

·         Carriage. Rough timber supporting the steps of wood stairs.

·         Stringers. Inclined members along the sides of stairway. The stringer along a wall is called a wall stringer. Open stringers are those cut to follow the lines of risers and tread. Closed stringer have parallel top and bottom and treads and risers are supported along their sides or mortised into them. In wood stairs, stringers are placed outside the carriage to provide a finish.

·         Railing. Framework or enclosure supporting a handrail and serving as a safety barrier.

·         Baluster. Vertical member supporting the handrail in a railing.

·         Balustrade. A railing composed of balusters capped by a handrail.

·         Handrail. Protective bar placed at a convenient distance above the stairs for a handhold.

·         Newel Post. Post a which the railing terminates at each floor level.

·         Angle Post. Railing support at landings or other breaks in the stairs. If the angle post projects beyond the bottom of the stringers, the ornamental detail formed at the bottom of the post is called the drop.

·         Winders. Steps with tapered treads in sharply curved stairs.

·         Headroom. Minimum clear height from a trad to overhead construction, such as the ceiling or next floor, ductwork, or piping.