Briefly describe what is meant by nominal protection factor
QUESTION 1
(a) Selection of a proper fan can be complicated and should be done by a ventilation or fan expert. Describe the criteria that should be considered in the selection of fans appropriate for a workplace.
(b) (i) List the advantages and disadvantages of installing a Local Exhaust Ventilation system at a workplace.
(ii) Explain the term “Air changes” used in measuring the dilution ventilation rate.
(c) Calculate the volume flow rate that would be required to ventilate a hall where an international conference is being held with the following dimensions: 18 m long, 20 m wide and 5 m high. Select the recommended number of air changes for your calculations.
QUESTION 2
(a) Describe the importance of having good lighting at a workplace.
(b) The design illuminance of a room is 300 lux on a working plane, which is 0.85 m above the floor. The room is 9 m wide, 20 m long. The height of the ceiling above the floor is 4.2 m. (i) calculate the room index.
(ii) Suppose the tables from the lamp manufacturer gives an utilisation factor of 0.5 and taking the maintenance factor as 0.8 for this type of lighting installation and situation, calculate the total installed luminous flux required.
(iii) Find the number of luminaires to be installed if they are fitted with twin fluorescent lamps given the lighting designed lumen output of chosen 75 W lamp is 3600
QUESTION 3
(a) Discuss on the factors that should be taken into consideration prior to the use of respiratory protective equipment by employees when exposed to dusts, chemicals or reduced oxygen.
(b) (i) Briefly describe what is meant by Nominal Protection Factor.
(ii) If a respiratory mask with an NPF of 9 is worn by a worker in a working atmosphere containing 45 mg/m³, determine the concentration of dust in air that the worker will breathe inside the mask (iii) Under OSHA 2005, the Occupational Exposure Standard for total inhalable dust is 10 mg/m³, what should be the NPF of the mask that employees should wear to meet the required standard if the workplace air contains 160 mg/m³?
