8. You are the city engineer sitting in a discussion about a program to give ker
ID: 290855 • Letter: 8
Question
8. You are the city engineer sitting in a discussion about a program to give kerosene heaters to needy people. Recent inspections of target homes show that the air exchange rates (Q/V) at present to be an average 4 per hour. Before the heaters are given away, the city, with the help of a team of volunteers will fix windows, caulk and add insulation so that any home receiving the heater will be at most 1.5 air exchanges per hour. The manufacturer specs show that the heaters will produce 23 mg of carbon monoxide per second. If the average home will use one heater in the living room (500 m) and one in each of the three bedrooms (each 400 m'), do you foresee any problems with this plan? Would you want to live and sleep in a home with these CO concentrations (e.g. based health standards)? Support your recommendation in a memo to the mayor and city on council. (20 points)Explanation / Answer
Given that the heater produces 23 mg/sec of CO, so one heater will produce 82.8 g/hr of CO, four heaters in each house will produce 331.2 g/hr of CO.
Using the formula of air exchange
n = q/v
where n is the number of times the air is replaced, q is the fresh supply of air, v is the volume of the region.
Given is n = 1.5 per hour, v = 1700m3
Airflow after insulation is 1.5 x 1700 = 2550 m3/hr, i.e. the fresh supply of air in 1 hour is 2550 m3 in the house.
It is known from the safety standards that 0.2 ppm or 0.2 g/m3 is the safe limit of CO.
1700 m3 x 0.2 g/m3 = 340 g should be the safe CO limit in each house.
2550 m3 x 0.2 g/m3 = 510 g should be the safe CO limit in one hour for each house after the insulations. This implies that 510 g for every 340 g of CO produced in each house should be replaced which will be rendered safe for each house. Since the heaters in each house produce 331.2 g/hr of CO, all of it will be replaced with insulations providing 1.5 exchanges per hour. Based on health standards, the CO limit of 9 ppm is recommended for indoors whereas levels exceeding 10 ppm can cause long-term health effects. So, the CO concentrations produced by the heaters will not cause problems with this plan.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.