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Table 2. Diameter of Area Sighted Through Various Lengths of 3/4-in. Pipe Without Orifice, in inches.
Length of
Pipe-in.
6
1
6.3
2
3.5
3
2.6
4
2.1
5
1.8
6
1.6
7
1.5
8
1.4
Table 3. Diameter of Area Sighted Through Various Lengths of 3/4-in. Pipe Without Orifice, in mm.
Length of
Pipe--mm
152.4
304.8
25.4
160.0
302.3
50.8
88.9
160.0
76.2
66.0
111.8
101.6
53.3
127.0
45.7
152.4
40.6
177.8
38.1
203.2
35.6
INSTALLING AN ORIFICE PLATE
An orifice plate with a hexagonal orifice diameter of 0.125 in.
(3.2 mm) is supplied with the C7915A Infrared Flame Detector.
The orifice can be mounted in front of the cell in the seal-off
adapter or in a standard 3/4 in. coupling. (Refer to Fig. 1.)
Cell To Orifice
Distance (in.)
12
1
3.2
2
1.6
3
1.1
4
Less than 1
5
-
6
-
Cell To Orifice
Distance (mm)
12
25.4
81.3
50.8
40.6
76.2
27.9
101.6
Less than 25.4
127.0
-
152.4
-
Distance From End of Pipe To Sighted Area-in.
12
18
24
11.9
17.6
23.2
6.3
9.1
11.9
4.4
6.3
8.2
3.5
4.9
6.3
2.9
4.1
5.2
2.6
3.5
4.4
2.3
3.1
3.9
2.1
2.8
3.5
Distance From End of Pipe To Sighted Area-mm
457.2
609.6
447.0
589.3
231.1
302.3
160.0
208.3
88.9
124.5
160.0
73.7
104.1
132.1
66.0
88.9
111.8
58.4
78.7
99.1
53.3
71.1
88.9
Table 4. Diameter of Area Sighted Through Orifice, in inches.
Distance From Orifice To Sighted Area-in.
24
6.1
3.2
2.1
1.6
1.3
1.1
Table 5. Diameter of Area Sighted Through Orifice, in mm.
Distance From Orifice To Sighted Area-mm.
24
154.9
81.3
53.3
40.6
33.0
27.9
30
36
42
28.4
34.5
14.8
17.6
20.4
10.1
11.9
12.9
7.8
9.1
10.6
6.3
7.5
8.6
4.3
6.3
7.3
4.7
5.5
6.3
4.2
4.9
5.6
762.0
914.4
1066.8
721.4
876.3
375.9
447.0
518.2
256.5
302.3
327.7
198.1
231.1
269.2
160.0
190.5
218.4
137.2
160.0
185.4
119.4
139.7
160.0
106.7
124.5
142.2
The size of the sighted area at various distances can be
determined from Table 4 or 5. For example, if the distance from
the photocell to a 0.125 in. (3.175 mm) diameter orifice is 4 in.
(101.6 mm), and from the orifice to the flame junction (or
refractory) is 36 in. (914.4 mm), the diameter of the sighted
area is 2.4 in. (61 mm).
Fig. 3 shows how a typical orifice plate restricts the view of a
small area around the flame junction.
Orifice Diameter-in.
0.125
36
8.8
4.6
6.1
3.2
4.2
2.4
3.2
1.9
2.5
1.6
2.1
Orifice Diameter-in.
0.125
36
223.5
116.8
154.9
81.3
106.7
61.0
81.3
48.3
63.5
40.6
53.3
5
C7915A INFRARED FLAME DETECTOR
48
54
60
23.2
26.0
28.9
15.7
17.6
19.5
11.9
13.4
14.8
9.7
10.7
11.9
8.2
9.1
10.1
7.1
8.0
8.7
6.3
7.1
7.7
1219.2
1371.6
1524.0
589.3
660.4
734.1
398.8
447.0
495.3
302.3
340.4
375.9
246.4
271.8
302.3
208.3
231.1
256.5
180.3
203.2
221.0
160.0
180.3
195.6
48
60
Over 10
7.6
5.2
3.9
3.2
2.6
48
60
Over 254.0
193.0
132.1
99.1
81.3
66.0
66
72
31.7
34.5
21.3
23.2
16.2
17.6
13.1
14.2
11.0
11.9
9.6
10.4
8.5
9.1
1676.4
1828.8
805.2
876.3
541.0
589.3
411.5
447.0
332.7
360.7
279.4
302.3
243.8
264.2
215.9
231.1
72
8.8
6.1
4.6
3.8
3.2
72
223.5
154.9
116.8
96.5
81.3
65-0292-06
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