Assignments - Science - Materials

A) ENVIRONMENTAL (13%)

  1. Design a lighting scheme for a room measuring 20m x 8m x 2.7m high if the design illuminance is 350 lux. The utilization factor is 0.5 and the maintenance factor is 0.8. If the LDL of the fittings is 2720 lumens calculate the number of fittings required and if the Spacing to Mounting Height ratio is 1.5:1.0 show on a suitable drawing an acceptable lighting layout.



B) PROPERTIES OF MATERIALS ( 12%)

  1. Describe two ways in which dampness is restricted from entering buildings with relevance to the PIA building. List the materials used and produce sketches to assist your description.

    (marks 5)

  2. What are the advantages of using polyethylene pipework for underground mains water and gas services?
    How may an underground plastic pipe be traced from above ground level?

    (marks 2)

  3. List material types suitable for:

    (a) Cold Water service (inside)
    (b) Cold Water service (outside)
    (c) Hot Water service (inside)
    (d) L.T.H.W.
    (e) Soils/Wastes
    (f) Surface water drainage
    (g) Sewage
    (h) Steam
    (i) Condensate
    (j) Compressed Air
    (k) L.P.G.
    (l) Heating Oil 28secs

    (marks 5)

Answer by Alan Luney

A): Environmental

Lighting Design.

1

Room measures 20m / 8m / 2.7m high. Design illuminance is 350 lux. Utilization factor is 0.5 & maintenance factor is 0.8. The LDL of the fittings is 2720.

Four rows of thirteen lights to meet the desired spacing to mounting ratio 1.5: 1.0. With a space of 2m horizontally and 1.5m vertically between each fitting we get a ratio of 1.31: 1.0.

 

 

B): Properties of Materials.

2a

To prevent dampness entering a building a DPC membrane must be installed in the brickwork above ground level and located higher than the DPM which is embedded between the floor screed and the concrete floor slab. The DPC must not bridge across the cavity wall, as this would allow moisture to travel from the outside wall onto the inside wall. The DPC and DPM would be cut and folded into one another to make a damp proof seal.

 

2b

To prevent dampness entering the building at a window opening a DPC is sandwiched between the brickwork and the top of the lintel. The DPC is angled down from the inside forming a steep incline therefore restricting any chance of dampness travelling onto the inside wall.

 

 

3

Advantages of using polyethylene pipework for underground services are:

1/ Doesn’t corride.

2/ Easier to install because of weight and flexibility.

3/ More robust.

4/ Less likely to cause condensation as walls are thick and have good insulation qualities.

5/ The electrofusion joints are very strong and reliable.

6/ The cost is cheaper than copper and installation charges are lower because it takes less time to install.

7/ They are colour coded therefore during excavation the service can be identified by the pipes colour.

8/ There is no reaction between plastic and metal so it can be connected to an excisting service.

9/ The installation does not need to be earth bonded.

Underground plastic pipes may be traced from above ground level by sounding the ground in the location of the pipe line. By doing this water flow can be heard and consequently the operator may pin point the pipe as the amplification of the flow increases.


4

Material types suitable for:

  1. Cold water services (inside): polythene, copper, uPVC.
  2. Cold water services (outside): polythene, copper, stainless steel.
  3. Hot water services (inside): copper, galvanised steel.
  4. L.T.H.W.: black steel, steel, copper.
  5. Soils/ Wastes: stainless steel, chemical lead, cast iron, silicon iron (spun), chemical stoneware, vitreous enamel, rubber lined, glass lined, hard rubber, glazed fireclay, copper, glass, polythene, uPVC, polypropylene, chloroprene canvas hose.
  6. Surface water drainage: plastic, cast iron, polythene.
  7. Sewage: cast iron, copper, plastic, vulcathene.
  8. Steam: black steel, steel, copper.
  9. Condensate: copper.
  10. Compresssd air: galvanised steel, copper, aluminium.
  11. L.P.G.: copper.
  12. Heating oil 28secs: black steel, steel, copper.
Assignments - Science - Materials