The Clean Air (Emission of Grit and Dust from Furnaces) Regulations 1971

SCHEDULE 1 FURNACES RATED BY HEAT OUTPUT

Schedule 1 furnaces

1.  The expression “ schedule 1 furnace” means a furnace of—

(a) a boiler or

(b) an indirect heating appliance in which the material heated is a gas or liquid; and where any such furnace falls also within the definition of “schedule 2 furnace”, it shall be treated for the purposes of these regulations as a schedule 1 furnace.

Heat output

2.  The quantities of grit and dust which may be emitted from the chimney of a schedule 1 furnace shall be ascertained by reference to heat output, designated by Maximum Continuous Rating of the boiler or appliance in pounds of steam per hour (from and at 100°C. (212°F)) or in thousands of British thermal units per hour.

Quantities which may be emitted

3.—(1) Subject to the provisions of paragraph 4 below, the quantities of grit and dust, in pounds per hour, which may be emitted by the chimney of a schedule 1 furnace the heat output of which is within the highest and lowest values specified in column (1) of the following table shall not exceed—

(a) if the furnace burns solid matter, the quantities prescribed in column (2) against the value representing the output of that furnace or

(b) if the furnace burns liquid matter, the quantities prescribed in column (3) against that value.

Maximum Continuous Rating in pounds of steam per hour (from and at 100°C. (212°F.)) or in thousands of British thermal units per hour	Maximum permitted quantities of grit and dust in pounds per hour
	Furnaces burning solid matter	Furnaces burning liquid matter
(1)	(2)	(3)
825	1.10	0.25
1,000	1.33	0.28
2,000	2.67	0.56
3,000	4.00	0.84
4,000	5.33	1.12
5,000	6.67	1.4
7,500	8.50	2.1
10,000	10.00	2.8
15,000	13.33	4.2
20,000	16.67	5.6
25,000	20.0	7.0
30,000	23.4	8.4
40,000	30	11.2
50,000	37	12.5
100,000	66	18
150,000	94	24
200,000	122	29
250,000	149	36
300,000	172	41
350,000	195	45
400,000	217	50
450,000	239	54.5
475,000	250	57

Limitation on grit

4.  In the case of a schedule 1 furnace which burns solid matter, the prescribed quantities may not contain more than the following proportion of particles exceeding 76 microns in diameter, that is to say—

(a) 33% where the Maximum Continuous Rating does not exceed 16,800 pounds per hour of steam or 16,800,000 British thermal units per hour or

(b) 20% in any other case.