Submittal Sheet

C7915A INFRARED FLAME DETECTOR
5 65-0292
.
INSTALLING AN ORIFICE PLATE
An orifice plate with a hexagonal orifice diameter of 0.125 in.
(3.2 mm) is available for 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.)
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.
Table 2. Diameter of Area Sighted Through Various Lengths of 3/4-in. Pipe Without Orifice, in in.
Length of
Pipe—in.
Distance From End of Pipe To Sighted Area—in.
6 1218243036424854606672
1 6.3 11.9 17.6 23.2 28.4 34.5 Over 40
2 3.5 6.3 9.1 11.9 14.8 17.6 20.4 23.2 26.0 28.9 31.7 34.5
3 2.6 4.4 6.3 8.2 10.1 11.9 12.9 15.7 17.6 19.5 21.3 23.2
4 2.1 3.5 4.9 6.3 7.8 9.1 10.6 11.9 13.4 14.8 16.2 17.6
5 1.8 2.9 4.1 5.2 6.3 7.5 8.6 9.7 10.7 11.9 13.1 14.2
6 1.6 2.6 3.5 4.4 4.3 6.3 7.3 8.2 9.1 10.1 11.0 11.9
7 1.5 2.3 3.1 3.9 4.7 5.5 6.3 7.1 8.0 8.7 9.6 10.4
8 1.4 2.1 2.8 3.5 4.2 4.9 5.6 6.3 7.1 7.7 8.5 9.1
Table 3. Diameter of Area Sighted Through Various Lengths of 3/4-in. Pipe Without Orifice, in mm.
Length of
Pipe-—mm
Distance From End of Pipe To Sighted Area—mm
152.4 304.8 457.2 609.6 762.0 914.4 1066.8 1219.2 1371.6 1524.0 1676.4 1828.8
25.4 160.0 302.3 447.0 589.3 721.4 876.3 Over 1016.0
50.8 88.9 160.0 231.1 302.3 375.9 447.0 518.2 589.3 660.4 734.1 805.2 876.3
76.2 66.0 111.8 160.0 208.3 256.5 302.3 327.7 398.8 447.0 495.3 541.0 589.3
101.6 53.3 88.9 124.5 160.0 198.1 231.1 269.2 302.3 340.4 375.9 411.5 447.0
127.0 45.7 73.7 104.1 132.1 160.0 190.5 218.4 246.4 271.8 302.3 332.7 360.7
152.4 40.6 66.0 88.9 111.8 137.2 160.0 185.4 208.3 231.1 256.5 279.4 302.3
177.8 38.1 58.4 78.7 99.1 119.4 139.7 160.0 180.3 203.2 221.0 243.8 264.2
203.2 35.6 53.3 71.1 88.9 106.7 124.5 142.2 160.0 180.3 195.6 215.9 231.1
Table 4. Diameter of Area Sighted Through Orifice, in in.
Cell To Orifice
Distance (in.)
Orifice Diameter—in.
0.125
Distance From Orifice To Sighted Area—in.
12 24 36 48 60 72
1 3.2 6.1 8.8 Over 10
2 1.6 3.2 4.6 6.1 7.6 8.8
3 1.1 2.1 3.2 4.2 5.2 6.1
4 Less than 1 1.6 2.4 3.2 3.9 4.6
5 — 1.3 1.9 2.5 3.2 3.8
6 — 1.1 1.6 2.1 2.6 3.2
Table 5. Diameter of Area Sighted Through Orifice, in mm.
Cell To Orifice
Distance (mm)
Orifice Diameter—in.
0.125
Distance From Orifice To Sighted Area—mm.
12 24 36 48 60 72
25.4 81.3 154.9 223.5 Over 254.0
50.8 40.6 81.3 116.8 154.9 193.0 223.5
76.2 27.9 53.3 81.3 106.7 132.1 154.9
101.6 Less than 25.4 40.6 61.0 81.3 99.1 116.8
127.0 — 33.0 48.3 63.5 81.3 96.5
152.4 — 27.9 40.6 53.3 66.0 81.3