Chapter XXXVI: Boilers for Stationary Steam Engines (2)

------+---+----+----+----+----+----+------+----+----+----+----+----
No. | A | B | C | D | E | F | G | H | I | J | K | L
------+---+----+----+----+----+----+------+----+----+----+----+----
|Ft.|Ins.|Ins.|Ins.|Ins.|Ins.| Ins. |Ins.|Ins.|Ins.|Ins.|Ins.
1 | 7| 32 | 12 | 20 | 16 | 45 |44 | 7 | 32 | 64 | 85 | 26
2 | 7| 34 | 12 | 20 | 16 | 48 |47 | 8 | 34 | 66 | 90 | 26
3 | 8| 36 | 12 | 20 | 16 | 48 |47 | 8 | 36 | 68 | 92 | 26
3-1/2| 10| 36 | 12 | 20 | 16 | 48 |47 | 8 | 36 | 68 | 92 | 26
4 | 8| 42 | 14 | 20 | 16 | 48 |47 | 8 | 42 | 74 | 98 | 27
5 | 10| 42 | 14 | 20 | 16 | 48 |47 | 8 | 42 | 74 | 98 | 27
6 | 10| 44 | 14 | 24 | 16 | 48 |47 | 10 | 44 | 76 |100 | 27
7 | 12| 44 | 14 | 24 | 16 | 48 |46-1/2| 10 | 44 | 76 |100 | 27
7-1/2| 14| 44 | 14 | 24 | 16 | 47 |45-1/2| 10 | 44 | 76 | 99 | 26
8 | 12| 48 | 16 | 24 | 16 | 47 |45-1/2| 10 | 48 | 88 |103 | 26
9 | 14| 48 | 16 | 24 | 16 | 47 |45-1/2| 10 | 48 | 88 |103 | 26
10 | 12| 54 | 16 | 24 | 20 | 50 |48-1/2| 10 | 54 | 94 |112 | 26
10-1/2| 15| 54 | 16 | 24 | 20 | 50 |48-1/2| 10 | 54 | 94 |112 | 26
11 | 12| 60 | 18 | 24 | 20 | 50 |48-1/2| 12 | 60 |108 |118 | 26
12 | 14| 60 | 18 | 24 | 20 | 50 |48-1/2| 12 | 60 |108 |118 | 26
13 | 16| 60 | 18 | 26 | 20 | 50 |48 | 12 | 60 |108 |118 | 26
14 | 15| 66 | 18 | 28 | 20 | 50 |48-1/2| 12 | 66 |114 |124 | 26
15 | 16| 66 | 18 | 28 | 20 | 50 |48 | 12 | 66 |114 |124 | 26
16 | 16| 72 | 20 | 30 | 20 | 50 |48 | 12 | 72 |120 |130 | 26
------+---+----+----+----+----+----+------+----+----+----+----+----

------+----+-------+----+----+----+----+----+----+----+------+------
| | | | | | | | | | | NO.
| | | | | | | | | | |COMMON
| | | | | | | | | | |BRICK
| | | | | | | | | |NO. OF|ABOVE
No. | M | N | O | P | Q | R | S | T | U | FIRE |FLOOR
| | | | | | | | | |BRICK.|LEVEL.
------+----+-------+----+----+----+----+----+----+----+------+------
|Ins.|Ft.Ins.|Ins.|Ins.|Ins.|Ins.|Ins.|Ins.|Ins.| |
1 | 19 | 11-6 | 20 | 40 | 12 | 16 | 36 | 34 | 4 | 600 | 6800
2 | 22 | 11-6 | 20 | 40 | 12 | 16 | 36 | 34 | 4 | 600 | 7500
3 | 22 | 12-6 | 24 | 40 | 12 | 16 | 36 | 34 | 4 | 650 | 7700
3-1/2| 22 | 14-6 | 28 | 46 | 12 | 16 | 42 | 42 | 4 | 720 | 8500
4 | 21 | 12-8 | 24 | 40 | 12 | 16 | 36 | 34 | 4 | 730 | 8500
5 | 21 | 14-8 | 28 | 46 | 12 | 16 | 42 | 42 | 4 | 770 | 9600
6 | 21 | 15-0 | 28 | 46 | 12 | 16 | 42 | 42 | 4 | 880 | 10500
7 | 21 | 17-0 | 32 | 52 | 12 | 16 | 48 | 49 | 4 | 940 | 10800
7-1/2| 21 | 19-0 | 36 | 58 | 12 | 16 | 54 | 84 | 4 | 1120 | 11500
8 | 21 | 17-2 | 32 | 52 | 12 | 20 | 48 | 49 | 4 | 1120 | 13600
9 | 21 | 19-2 | 36 | 58 | 12 | 20 | 54 | 84 | 4 | 1140 | 15700
10 | 24 | 17-6 | 32 | 52 | 12 | 20 | 48 | 49 | 4 | 1160 | 16200
10-1/2| 24 | 20-8 | 36 | 56 | 16 | 20 | 54 | 90 | 4 | 1270 | 17500
11 | 24 | 17-10 | 32 | 50 | 16 | 24 | 48 | 49 | 4 | 1400 | 20500
12 | 24 | 19-10 | 36 | 56 | 16 | 24 | 54 | 84 | 4 | 1500 | 23000
13 | 24 | 22-0 | 40 | 56 | 16 | 24 | 54 | 96 | 4 | 1540 | 25300
14 | 24 | 21-2 | 36 | 56 | 16 | 24 | 54 | 90 | 4 | 1590 | 26000
15 | 24 | 22-2 | 40 | 56 | 16 | 24 | 54 | 96 | 4 | 1620 | 27000
16 | 24 | 22-6 | 40 | 56 | 16 | 24 | 54 | 96 | 4 | 1750 | 30000
------+----+-------+----+----+----+----+----+----+----+------+------

NOTE.--In setting "Standard" boilers, the side walls should be so built that the longitudinal seams of the shell will be protected from the fire.

MEASUREMENTS FOR SETTING TUBULAR STATIONARY BOILERS WITH HALF ARCH FRONTS.

REFERENCE LETTERS ON DIAGRAMS.

------+---+----+----+----+----+------+------+----+----+----+-------
No. | A | B | C | D | E | F | G | H | I | J | K
------+---+----+----+----+----+------+------+----+----+----+-------
|Ft.|Ins.|Ins.|Ins.|Ins.|Ins. | Ins. |Ins.|Ins.|Ins.| Ins.
1 | 7 | 32 | 14 | 20 | 16 |46 |45 | 7 | 32 | 64 | 73
2 | 7 | 34 | 14 | 20 | 16 |46 |45 | 8 | 34 | 66 | 75
3 | 8 | 36 | 14 | 20 | 16 |46 |45 | 8 | 36 | 68 | 77
3-1/2|10 | 36 | 14 | 20 | 16 |46 |45 | 8 | 36 | 68 | 77
4 | 8 | 42 | 18 | 20 | 16 |46 |45 | 8 | 42 | 74 | 83
5 |10 | 42 | 18 | 20 | 16 |46 |45 | 8 | 42 | 74 | 83
6 |10 | 44 | 18 | 24 | 16 |46 |45 | 10 | 44 | 76 | 85
7 |12 | 44 | 18 | 24 | 16 |46 |44-1/2| 10 | 44 | 76 | 85
7-1/2|14 | 44 | 18 | 24 | 16 |46 |44-1/2| 10 | 44 | 76 | 85
8 |12 | 48 | 19 | 24 | 16 |50 |48-1/2| 10 | 48 | 88 | 93
9 |14 | 48 | 19 | 24 | 16 |50 |48-1/2| 10 | 48 | 88 | 93
10 |12 | 54 | 19 | 24 | 20 |50 |48-1/2| 10 | 54 | 94 | 99
10-1/2|15 | 54 | 19 | 24 | 20 |50 |48-1/2| 10 | 54 | 94 | 99
11 |12 | 60 | 21 | 24 | 20 |46-3/4|45-1/2| 12 | 60 |108 |101-3/4
12 |14 | 60 | 21 | 24 | 20 |46-3/4|45 | 12 | 60 |108 |101-3/4
13 |16 | 60 | 21 | 26 | 20 |46-3/4|45 | 12 | 60 |108 |101-3/4
14 |15 | 66 | 24 | 28 | 20 |47 |45-1/2| 12 | 66 |114 |108
15 |16 | 66 | 24 | 28 | 20 |47 |45-1/2| 12 | 66 |114 |108
16 |16 | 72 | 24 | 30 | 20 |48 |46-1/2| 12 | 72 |120 |115
------+---+----+----+----+----+------+------+----+----+----+-------

------+------+------+--------+----+------+----+----+----+----+----
No. | L | M | N | O | P | Q | R | S | T | U
------+------+------+--------+----+------+----+----+----+----+----
| Ins. | Ins. |Ft. Ins.|Ins.| Ins. |Ins.|Ins.|Ins.|Ins.|Ins.
1 |26 |20 | 10-3 | 20 |33 | 12 | 16 | 36 | 34 | 4
2 |26 |20 | 10-3 | 20 |33 | 12 | 16 | 36 | 34 | 4
3 |26 |20 | 11-3 | 24 |33 | 12 | 16 | 36 | 34 | 4
3-1/2|26 |20 | 13-3 | 28 |39 | 12 | 16 | 42 | 42 | 4
4 |27 |19 | 11-3 | 24 |32-1/2| 12 | 16 | 36 | 34 | 4
5 |27 |19 | 13-3 | 28 |38-1/2| 12 | 16 | 42 | 42 | 4
6 |27 |19 | 13-7 | 28 |38-1/2| 12 | 16 | 42 | 42 | 4
7 |27 |19 | 15-7 | 32 |44-1/2| 12 | 16 | 48 | 49 | 4
7-1/2|27 |19 | 17-7 | 36 |50-1/2| 12 | 16 | 54 | 84 | 4
8 |26 |24 | 15-7 | 32 |48 | 12 | 20 | 48 | 49 | 4
9 |26 |24 | 17-7 | 36 |54 | 12 | 20 | 54 | 84 | 4
10 |26 |24 | 15-11 | 32 |48-1/2| 12 | 20 | 48 | 49 | 4
10-1/2|26 |24 | 19-1 | 36 |52-1/2| 16 | 20 | 54 | 90 | 4
11 |26 |20-3/4| 16-1 | 32 |47 | 16 | 24 | 48 | 49 | 4
12 |26 |20-3/4| 18-1 | 36 |53 | 16 | 24 | 54 | 84 | 4
13 |26 |20-3/4| 20-3 | 40 |53 | 16 | 24 | 54 | 96 | 4
14 |26 |21 | 19-5 | 36 |52-1/2| 16 | 24 | 54 | 90 | 4
15 |26 |21 | 20-5 | 40 |52-1/2| 16 | 24 | 54 | 96 | 4
16 |28-1/4|19-3/4| 20-7 | 40 |52-1/2| 16 | 24 | 54 | 96 | 4
------+------+------+--------+----+------+----+----+----+----+----

------+------+------+----+----+----+------+------
| | | | | | | NO.
| | | | | | |COMMON
| | | | | | |BRICK
| | | | | |NO. OF|ABOVE
No. | V | W | X | Y | Z | FIRE |FLOOR
| | | | | |BRICK.|LEVEL.
------+------+------+----+----+----+------+------
| Ins. | Ins. |Ins.|Ins.|Ins.| |
1 |36 | 9 | 24 | 12 | 7 | 600 | 6150
2 |36 | 9 | 28 | 12 | 7 | 600 | 6200
3 |36 | 9 | 28 | 12 | 15 | 650 | 6700
3-1/2|36 | 9 | 28 | 12 | 25 | 720 | 7050
4 |32-3/4|12-1/4| 32 | 16 | 11 | 730 | 7700
5 |32-3/4|12-1/4| 32 | 16 | 25 | 770 | 8700
6 |32-3/4|12-1/4| 36 | 16 | 25 | 880 | 8800
7 |32-1/4|12-1/4| 36 | 20 | 35 | 940 | 9300
7-1/2|32-1/4|12-1/4| 36 | 24 | 45 | 1120 | 9500
8 |36-1/4|12-1/4| 36 | 20 | 35 | 1120 | 11100
9 |36-1/4|12-1/4| 36 | 24 | 45 | 1140 | 12900
10 |34 |14-1/2| 42 | 20 | 35 | 1160 | 13200
10-1/2|34 |14-1/2| 42 | 24 | 57 | 1270 | 14200
11 |31 |14-1/2| 48 | 20 | 37 | 1400 | 16700
12 |30-1/2|14-1/2| 48 | 24 | 45 | 1500 | 19200
13 |30-1/2|14-1/2| 48 | 24 | 65 | 1540 | 21500
14 |31 |14-1/2| 54 | 24 | 57 | 1590 | 22100
15 |31 |14-1/2| 54 | 24 | 65 | 1620 | 23100
16 |27-1/2|19 | 54 | 24 | 65 | 1750 | 26000
------+------+------+----+----+----+------+------

NOTE.--In setting "Standard" boilers, the side walls should be so built that the longitudinal seams of the shell will be protected from the fire.

THE EVAPORATIVE EFFICIENCIES OF BOILERS.

[56]"Many tests have been undertaken to ascertain the evaporative power of different classes of boilers in actual work; but few of these are of any value, owing to the unreliable means usually employed to measure the quantity of water evaporated. The easiest method, and consequently the one most frequently adopted, is to measure the quantity by the difference of its height in the water-gauge glass at the beginning and end of the trial, and also at intermediate stages. This method is very rude and uncertain, since there can be little doubt that in many boilers at work the surface of the water is not level, but is usually higher over the furnace, or where the greatest ebullition occurs. The difference in height at any moment will greatly depend upon the intensity of the ebullition, which is ever varying during the intervals between firing. With mechanical firing the difference of height is probably reduced to a minimum.

[56] From "_A Treatise on Steam Boilers_," by Robert Wilson.

"The meters employed for measuring the water are sometimes not trustworthy. The only sure method of ascertaining the quantity of water evaporated is by actual measurement with a cistern or vessel whose cubic contents are accurately known. The quantity of water in the boiler before and after the trial should be measured at the same temperature, which should not exceed 212° to insure accuracy. But even when the amount of water introduced and the quantity passed off from the boiler are accurately ascertained, there yet remains a doubt as to how much has been actually evaporated, and how much may have passed off in priming, unless the trial has been conducted with the boiler open to the atmosphere, which appears to be the only condition under which accuracy can be insured, unless a suitable apparatus can be provided for accurately measuring the weight and temperature of all the steam and water given off, when the boiler is working above atmospheric pressure.

"There are very few boilers that do not prime more or less, and the quantity of water passed off in this manner is sometimes very considerable, and has led to the impossible results of 16 and 17 lbs. of water evaporated per lb. of ordinary coal in locomotive and water-tube boilers being seriously recorded. Externally fired boilers, that have given the moderate result of 5 lbs. of water per lb. of coal at atmospheric pressure, have shown the unexpected result of 10 and 12 lbs. of water evaporated at 40 lbs. pressure. In fact, unless the amount of water passed over with the steam by priming or foaming, when working under pressure, can be accurately ascertained, the evaporative results are not to be relied upon, however careful in other respects the trial may have been conducted. It is customary to give the quantity of water evaporated from and at a temperature of 212°, or the boiling point at atmospheric pressure, to which the results of evaporation are reduced."

The quantity corresponding to any temperature of feed water and working pressure can readily be found with the aid of the annexed table, taken from _The Encyclopædia Britannica_, wherein are presented the relations of the properties of steam, as now accepted by the best authorities.

TABLE GIVING THE PRESSURE, TEMPERATURE, AND VOLUME OF STEAM.

-----------+-----------+-----------+----------+---------+-------------
Total pres-| | | | |Relative vol-
sure per |Gauge pres-| Sensible |Total heat|Weight of| ume of steam
square inch| sure or |temperature|in degrees|one cubic|compared with
measured | pressure | in |from zero |foot of | the water
from a | above | Fahrenheit| of | steam. |from which it
vacuum. |atmosphere.| degrees. | Fahren- | lbs. | was
lbs. | lbs. | | heit. | | evaporated.
-----------+-----------+-----------+----------+---------+-------------
1 | --- | 102.1 | 1144.5 | .0030 | 20582
2 | --- | 126.3 | 1151.7 | .0058 | 10721
3 | --- | 141.6 | 1156.6 | .0085 | 7322
4 | --- | 153.1 | 1160.1 | .0112 | 5583
5 | --- | 162.3 | 1162.9 | .0138 | 4527
6 | --- | 170.2 | 1165.3 | .0163 | 3813
7 | --- | 176.9 | 1167.3 | .0189 | 3298
8 | --- | 182.9 | 1169.2 | .0214 | 2909
9 | --- | 188.3 | 1170.8 | .0239 | 2604
10 | --- | 193.3 | 1172.3 | .0264 | 2358
11 | --- | 197.8 | 1173.7 | .0289 | 2157
12 | --- | 202.0 | 1175.0 | .0314 | 1986
13 | --- | 205.9 | 1176.2 | .0338 | 1842
14 | --- | 209.6 | 1177.3 | .0362 | 1720
14.7 | 0 | 212.0 | 1178.1 | .0380 | 1642
15 | .3 | 213.1 | 1178.4 | .0387 | 1610
16 | 1.3 | 216.3 | 1179.4 | .0411 | 1515
17 | 2.3 | 219.6 | 1180.3 | .0435 | 1431
18 | 3.3 | 222.4 | 1181.2 | .0459 | 1357
19 | 4.3 | 225.3 | 1182.1 | .0483 | 1290
20 | 5.3 | 228.0 | 1182.9 | .0507 | 1229
21 | 6.3 | 230.6 | 1183.7 | .0531 | 1174
22 | 7.3 | 233.1 | 1184.5 | .0555 | 1123
23 | 8.3 | 235.3 | 1185.2 | .0580 | 1075
24 | 9.3 | 237.8 | 1185.9 | .0601 | 1036
25 | 10.3 | 240.1 | 1186.6 | .0625 | 996
26 | 11.3 | 242.3 | 1187.3 | .0650 | 958
27 | 12.3 | 244.4 | 1187.8 | .0673 | 926
28 | 13.3 | 246.4 | 1188.4 | .0696 | 895
29 | 14.3 | 248.4 | 1189.1 | .0719 | 866
30 | 15.3 | 250.4 | 1189.8 | .0743 | 838
31 | 16.3 | 252.2 | 1190.4 | .0766 | 813
32 | 17.3 | 254.1 | 1190.9 | .0779 | 789
33 | 18.3 | 255.9 | 1191.5 | .0812 | 767
34 | 19.3 | 257.6 | 1192.0 | .0835 | 746
35 | 20.3 | 259.3 | 1192.5 | .0858 | 726
36 | 21.3 | 260.9 | 1193.0 | .0881 | 707
37 | 22.3 | 262.6 | 1193.5 | .0905 | 688
38 | 23.3 | 264.2 | 1194.0 | .0929 | 671
39 | 24.3 | 265.8 | 1194.5 | .0952 | 655
40 | 25.3 | 267.3 | 1194.9 | .0974 | 640
41 | 26.3 | 268.7 | 1195.4 | .0996 | 625
42 | 27.3 | 270.2 | 1195.8 | .1020 | 611
43 | 28.3 | 271.6 | 1196.2 | .1042 | 598
44 | 29.3 | 273.0 | 1196.6 | .1065 | 595
45 | 30.3 | 274.4 | 1197.1 | .1089 | 572
46 | 31.3 | 275.8 | 1197.5 | .1111 | 561
47 | 32.3 | 277.1 | 1197.9 | .1133 | 550
48 | 33.3 | 278.4 | 1198.3 | .1156 | 539
49 | 34.3 | 279.7 | 1198.7 | .1179 | 529
50 | 35.3 | 281.0 | 1199.1 | .1202 | 518
51 | 36.3 | 282.3 | 1199.5 | .1224 | 509
52 | 37.3 | 283.5 | 1199.9 | .1246 | 500
53 | 38.3 | 284.7 | 1200.3 | .1269 | 491
54 | 39.3 | 285.9 | 1200.6 | .1291 | 482
55 | 40.3 | 287.1 | 1201.0 | .1314 | 474
56 | 41.3 | 288.2 | 1201.3 | .1336 | 466
57 | 42.3 | 289.3 | 1201.7 | .1364 | 458
58 | 43.3 | 290.4 | 1202.0 | .1380 | 451
59 | 44.3 | 291.6 | 1202.4 | .1403 | 444
60 | 45.3 | 292.7 | 1202.7 | .1425 | 437
61 | 46.3 | 293.8 | 1203.1 | .1447 | 403
62 | 47.3 | 294.8 | 1203.4 | .1469 | 424
63 | 48.3 | 295.9 | 1203.7 | .1493 | 417
64 | 49.3 | 296.9 | 1204.0 | .1516 | 411
65 | 50.3 | 298.0 | 1204.3 | .1538 | 405
66 | 51.3 | 299.0 | 1204.6 | .1560 | 399
67 | 52.3 | 300.0 | 1204.9 | .1583 | 393
68 | 53.3 | 300.9 | 1205.2 | .1605 | 388
69 | 54.3 | 301.9 | 1205.5 | .1627 | 383
70 | 55.3 | 302.9 | 1205.8 | .1648 | 378
71 | 56.3 | 303.9 | 1206.1 | .1670 | 373
72 | 57.3 | 304.8 | 1206.3 | .1692 | 368
73 | 58.3 | 305.7 | 1206.6 | .1714 | 363
74 | 59.3 | 306.6 | 1206.9 | .1736 | 359
75 | 60.3 | 307.5 | 1207.2 | .1759 | 353
76 | 61.3 | 308.4 | 1207.4 | .1782 | 349
77 | 62.3 | 309.3 | 1207.7 | .1804 | 345
78 | 63.3 | 310.2 | 1208.0 | .1826 | 341
79 | 64.3 | 311.1 | 1208.3 | .1848 | 337
80 | 65.3 | 312.0 | 1208.5 | .1869 | 333
81 | 66.3 | 312.8 | 1208.8 | .1891 | 329
82 | 67.3 | 313.6 | 1209.1 | .1913 | 325
83 | 68.3 | 314.5 | 1209.4 | .1935 | 321
84 | 69.3 | 315.3 | 1209.6 | .1957 | 318
85 | 70.3 | 316.1 | 1209.9 | .1980 | 314
86 | 71.3 | 316.9 | 1210.1 | .2002 | 311
87 | 72.3 | 317.8 | 1210.4 | .2024 | 308
88 | 73.3 | 318.6 | 1210.6 | .2044 | 305
89 | 74.3 | 319.4 | 1210.9 | .2067 | 301
90 | 75.3 | 320.2 | 1211.1 | .2089 | 298
91 | 76.3 | 321.0 | 1211.3 | .2111 | 295
92 | 77.3 | 321.7 | 1211.5 | .2133 | 292
93 | 78.3 | 322.5 | 1211.8 | .2155 | 289
94 | 79.3 | 323.3 | 1212.0 | .2176 | 286
95 | 80.3 | 324.1 | 1212.3 | .2198 | 283
96 | 81.3 | 324.8 | 1212.5 | .2219 | 281
97 | 82.3 | 325.6 | 1212.8 | .2241 | 278
98 | 83.3 | 326.3 | 1213.0 | .2263 | 275
99 | 84.3 | 327.1 | 1213.2 | .2285 | 272
100 | 85.3 | 327.9 | 1213.4 | .2307 | 270
101 | 86.3 | 328.5 | 1213.6 | .2329 | 267
102 | 87.3 | 329.1 | 1213.8 | .2351 | 265
103 | 88.3 | 329.9 | 1214.0 | .2373 | 262
104 | 89.3 | 330.6 | 1214.2 | .2393 | 260
105 | 90.3 | 331.3 | 1214.4 | .2414 | 257
106 | 91.3 | 331.9 | 1214.6 | .2435 | 255
107 | 92.3 | 332.6 | 1214.8 | .2456 | 253
108 | 93.3 | 333.3 | 1215.0 | .2477 | 251
109 | 94.3 | 334.0 | 1215.3 | .2499 | 249
110 | 95.3 | 334.6 | 1215.5 | .2521 | 247
111 | 96.3 | 335.3 | 1215.7 | .2543 | 245
112 | 97.3 | 336.0 | 1215.9 | .2564 | 243
113 | 98.3 | 336.7 | 1216.1 | .2586 | 241
114 | 99.3 | 337.4 | 1216.3 | .2607 | 239
115 | 100.3 | 338.0 | 1216.5 | .2628 | 237
116 | 101.3 | 338.6 | 1216.7 | .2649 | 235
117 | 102.3 | 339.3 | 1216.9 | .2674 | 233
118 | 103.3 | 339.9 | 1217.1 | .2696 | 231
119 | 104.3 | 340.5 | 1217.3 | .2738 | 229
120 | 105.3 | 341.1 | 1217.4 | .2759 | 227
121 | 106.3 | 341.8 | 1217.6 | .2780 | 225
122 | 107.3 | 342.4 | 1217.8 | .2801 | 224
123 | 108.3 | 343.0 | 1218.0 | .2822 | 222
124 | 109.3 | 343.6 | 1218.2 | .2845 | 221
125 | 110.3 | 344.2 | 1218.4 | .2867 | 219
126 | 111.3 | 344.8 | 1218.6 | .2889 | 217
127 | 112.3 | 345.4 | 1218.8 | .2911 | 215
128 | 113.3 | 346.0 | 1218.9 | .2933 | 214
129 | 114.3 | 346.6 | 1219.1 | .2955 | 212
130 | 115.3 | 347.2 | 1219.3 | .2977 | 211
131 | 116.3 | 347.8 | 1219.5 | .2999 | 209
132 | 117.3 | 348.3 | 1219.6 | .3020 | 208
133 | 118.3 | 348.9 | 1219.8 | .3040 | 206
134 | 119.3 | 349.5 | 1220.0 | .3060 | 205
135 | 120.3 | 350.1 | 1220.2 | .3080 | 203
136 | 121.3 | 350.6 | 1220.3 | .3101 | 202
137 | 122.3 | 351.2 | 1220.5 | .3121 | 200
138 | 123.3 | 351.8 | 1220.7 | .3142 | 199
139 | 124.3 | 352.4 | 1220.9 | .3162 | 198
140 | 125.3 | 352.9 | 1221.0 | .3184 | 197
141 | 126.3 | 353.5 | 1221.2 | .3206 | 195
142 | 127.3 | 354.0 | 1221.4 | .3228 | 194
143 | 128.3 | 354.5 | 1221.6 | .3250 | 193
144 | 129.3 | 355.0 | 1221.7 | .3273 | 192
145 | 130.3 | 355.6 | 1221.9 | .3294 | 190
146 | 131.3 | 356.1 | 1222.0 | .3315 | 189
147 | 132.3 | 356.7 | 1222.2 | .3336 | 188
148 | 133.3 | 357.2 | 1222.3 | .3357 | 187
149 | 134.3 | 357.8 | 1222.5 | .3377 | 186
150 | 135.3 | 358.3 | 1222.7 | .3397 | 184
155 | 140.3 | 361.0 | 1223.5 | .3500 | 179
160 | 145.3 | 363.4 | 1224.2 | .3607 | 174
165 | 150.3 | 366.0 | 1224.9 | .3714 | 169
170 | 155.3 | 368.2 | 1225.7 | .3821 | 164
175 | 160.3 | 370.8 | 1226.4 | .3928 | 159
180 | 165.3 | 372.9 | 1227.1 | .4035 | 155
185 | 170.3 | 375.3 | 1227.8 | .4142 | 151
190 | 175.3 | 377.5 | 1228.5 | .4250 | 148
195 | 180.3 | 379.7 | 1229.2 | .4357 | 144
200 | 185.3 | 381.7 | 1229.8 | .4464 | 141
210 | 195.3 | 386.0 | 1231.1 | .4668 | 135
220 | 205.3 | 389.9 | 1232.3 | .4872 | 129
230 | 215.3 | 393.8 | 1233.5 | .5072 | 123
240 | 225.3 | 397.5 | 1234.6 | .5270 | 119
250 | 235.3 | 401.1 | 1235.7 | .5471 | 114
260 | 245.3 | 404.5 | 1236.8 | .5670 | 110
270 | 255.3 | 407.9 | 1237.8 | .5871 | 106
280 | 265.3 | 411.2 | 1238.8 | .6070 | 102
290 | 275.3 | 414.4 | 1239.8 | .6268 | 99
300 | 285.3 | 417.5 | 1240.7 | .6469 | 96
-----------+-----------+-----------+----------+---------+-------------

Here we see that at 212° the total quantity of heat in the steam is 1178.1°, which gives a difference of 966.1°. This heat, usually termed latent, is absorbed in performing the work of expanding the particles of water from the liquid to the gaseous state. Now, suppose the water is evaporated at 60 lbs. pressure, the steam will have a temperature of 307°, and a total heat of 1207°. If the feed has been introduced at 60°, it is evident that 1147° of heat have been imparted. As the amount evaporated is inversely proportional to the quantity of heat required, we have 1147 ÷ 966 = 1.2. Multiplying by this factor, the quantity evaporated at 60 lbs. pressure from 60°, we obtain the amount that would be evaporated at 212° by the same quantity of fuel.

By the same table can be ascertained the comparatively small increase of heat required to evaporate water at higher pressures. Suppose we take water evaporated at 45 lbs. pressure from a feed temperature of 60°, then each lb. of water will require 1202.7-60 = 1142.7 for its conversion into steam. If we take the pressure at 100 lbs., we shall have 1216.9-60 = 1156.9° as the quantity required. The difference between these two total quantities is only 14.2°, and is so small as to be scarcely worth considering. Leaving out of account the loss due to the slight reduction of the conducting power of the material, the increased amount of heat required for the higher pressure will be only 1/36 of the total heat required at 60 lbs. With an evaporation of 7 lbs. of water from 1 lb. of coal, it will be obtained by using 1/563 more fuel, or about 1 lb. in about 556 lbs., a quantity not appreciable to the ordinary modes of weighing coal. The economy is then manifest of using steam of high pressures when at the same time advantage is taken of the facilities it offers for working the steam more expansively to the engine cylinders.

The saving that may be effected by heating the feed water may be shown as follows:

If we take the normal temperature of the feed water at 60°, the temperature of the heated water at 212°, and the boiler pressure at 20 lbs., the total heat imparted to the steam in one case is

1192.5° - 60° = 1132.5°
and in the other case 1192.5° - 212° = 980.5°
152°
the difference being 152°, or a saving of -------
1132.5°

which is 13.4 per cent. If the pressure be taken at 120 lbs., instead of 20 lbs., the saving will be 13.1 per cent, showing a slight diminution in the economy effected by heating the feed water when a high boiler pressure is employed.

THE CARE AND MANAGEMENT OF STATIONARY ENGINE BOILERS.

The first thing to do in taking charge of a stationary engine boiler is to know from personal inspection that the safety fittings and the boiler-feeding apparatus are in good order.

The safety valve is the first thing to inspect, as it is liable to stick in its seat, especially in cases in which it is set at a greater pressure than is got up in the boiler, because in that case it is not lifted from the seat and in time sticks fast there.

In such cases it is proper to lift the valve at least once a day while steam is on. For this purpose a cord may be attached to the lever, passing over a pulley directly above the lever, and thence to some convenient place near the boiler, but where it is not liable to get caught and pulled accidentally.

Before lighting the fire, see that there is sufficient water in the boiler. If there is a gauge glass on the boiler, it should show three-quarters full, or three-quarters of a glass, as it is called.

The gauge glass may show a false water level, and to be sure that such is not the case, open the top gauge cock and the cock at the bottom of the gauge glass, letting the water run through the gauge glass. Open and close the cock below the gauge glass two or three times to see that the water comes to the same level each time.

If the steam pressure has been allowed to fall in the boiler without any of the cocks being opened, there will be a partial vacuum in the boiler, and air must be let in before the true water level will be shown either by the gauge glass or by the gauge cocks.

Opening the upper gauge cock will let in the air, and it should not be closed again until enough steam has been got up in the boiler to expel the air again, or in other words, until steam begins to issue from it.

The grate bars and ash pit should be cleaned of clinker, ashes, etc., and it should be seen that the tubes are clear of ashes, etc., before the fire is laid; if the grate is a shaking one, the lever should be applied to see that the grate will shake properly.

TO LIGHT THE FIRE--In the case of anthracite or hard coal, as it is sometimes termed, first cover the bars with a thin layer of coal and then put in pieces of lighted greasy waste (if it is at hand) distributed about the furnace, taking especial care to light the fire at the fire-door end and in the corners, because the fire will spread from the front end towards the back easier than it will from the back end towards the front.

The fire should light from the bottom and not from the top, hence the thinnest pieces of the wood should be put in first.

If there is any soft coal at hand, a small quantity of it will accelerate lighting the fire, as it burns easier and quicker than hard coal.

Before putting on the coal the wood should be well lighted, the bottom portion of it having ceased flaming.

This causes the lighted wood to spread over the bars and the fire to light evenly.

Charge the coal lightly, first covering the places that have burned up the most.

FIRING.--The fire door should be kept open as little as possible, as it admits cold air that is detrimental to the combustion, as well as to the draught, hence firing should be done quickly.

A good fireman will maintain as even a temperature as possible in the fire box by charging the coal lightly and quickly.

Some firemen will, after the fire is at its proper depth all over the grates, charge the fire in the front end, that is, at the fire-door end, and push it back as it burns up, to keep up the thickness of the fire at the back.

The thickness of the fire depends upon the size and kind of coal.

With small coal a fire from 4 to 6 inches deep will answer, while, if the lumps are five or six inches in diameter, a fire from a foot to 15 inches deep may be maintained, as is done in some locomotives.

The object is to have the fire thick enough to prevent it from burning through in spots or letting cold draughts of air pass through it.

The sides of the furnace require particular attention, not only because cold air is more likely to get through there, but also in boilers having fire boxes the cool sides of the box keep the temperature of the fuel down, hence a thicker fire is necessary around the sides than in the middle of the furnace or fire box.

Three things are to be considered in cleaning a fire--first, that the boiler pressure will fall during, and for a short time after, the cleaning; second, that the depth of fire will be diminished by the cleaning; and third, that the temperature of the fire will fall during the cleaning.

SHAKING GRATE BARS.

When a furnace has shaking grate bars, the cleaning of the fire is greatly facilitated, and with bars that shake singly (and good coal) the fire is often not disturbed during the day, except to shake the bars occasionally, passing the poker through it and using the hoe to keep it evenly spread.

If the grate shakes in sections, more cleaning will be required to break up the clinker, while, if the bars do not shake, the cleaning assumes greater importance.

Before cleaning, therefore, see that there is sufficient water in the boiler, that it need not be fed while cleaning, nor just after cleaning the fire.

Prepare for cleaning by having a thick fire on the grate, so that after cleaning it will burn up quickly, and let the cleaning be done as quickly as possible.

The tools used for cleaning the fire are the slice bar, Fig. 3288, which is pushed along the top of the fire bars to loosen up the fire, and let the ashes fall through the bars.

The hoe, Fig. 3289, which is used to push the fire to the back of the furnace and to pull it forward. The poker, Fig. 3290, which dislodges any clinker that may be between the bars, and lets the ashes fall through.

The clinker hook or devil's claw, Fig. 3291, which is used to haul clinker out of the fire, and the rake, Fig. 3292, which is used to spread the fire evenly over the bars after it is cleaned.

In cleaning a fire, first use the slice bar to loosen up the fire and let the ashes fall through, and also dislodge clinkers from the surface of the bars. Then push the fire to the back of the furnace. Next use the poker to clean out clinker from between the exposed part of the bars. Then with the hoe pull a part of the fire forward and pull out the clinker that may be in this part, doing so with the hoe as far as possible, as that will save time, but if it should be necessary, use the clinker hook.

Then pull forward a second portion of the fire, and spread it on the bars, removing the clinker as before. When all the fire has thus been cleaned, use the rake to spread it evenly over the bars, and put on a light charge of coal, covering the brightest parts of the fire first, and taking care that no part of the fire bars is left uncovered.

The cleaning should be done quickly.

DRAUGHT.--The draught should be decreased while the fire is being cleaned, but the damper should never be entirely closed, as this might cause an explosion in the fire box and tubes.

During a temporary interruption, as in the case of the engine stopping, partly close all the dampers, as it is wasteful to make steam and blow it off through the safety valve.

COMBUSTION.--A blue flame is evidence of incomplete combustion, but there may be a blue flame and imperfect combustion at the back end of the furnace, and a white flame and perfect combustion at the other end.

This is likely to occur with heavy firing near the fire door, and a thin fire at the tube sheet end of the fire box. In this case the unconsumed gases produced near the fire door (as evidenced by the blue flame) are consumed in passing over the bright fire at the tube plate end of the furnace.

AT NIGHT.--Always leave plenty of water in the boiler when leaving it for the night, not only to allow for any leak, but also because it gives a fair start in the morning and more time to remedy any defect in the feed pump if it arise.

By plenty of water, very nearly a full gauge is meant, or if there is no gauge glass to the boiler, let the water stand above the second or middle cock.

The usual method of leaving the fire for the night is to bank it. There is an element of danger, however, in banking a fire, unless it is done to suit the circumstances, because steam may generate very rapidly, and perhaps more rapidly than the safety valve can carry it off.

A safe method is to clean the fire, leaving the clinker and ashes covering the front half of the grate and the fire piled up on the back half.

The damper and ash pit door should be closed tight, the fire door open, and the fire well covered with fresh coal, choosing small rather than large coal.

If this method is found not to keep up the fire sufficiently, the same plan may be employed, except that the ashes and clinker may be removed, and if this still leaves too cold a boiler, and too poor a fire in the morning, the fire may be left spread over the grate, but heavily covered with fresh coal, the draught being stopped as much as possible by closing the dampers and opening the furnace door.

To further insure safety, the weight on the safety valve lever should be pushed towards the valve, so as to cause the safety valve to blow off at a less pressure than during the day.

IN THE MORNING.--In starting up a banked fire in the morning, first close the fire door and open the damper, so as to give the fire all the draught possible, and let it burn up a little; then, if it has been piled up at the back of the furnace, clean out the ashes by passing the T bar beneath the fire, and spread it over the grate, letting it burn up a little before making up a fire.

BOILER-FEED.--The fireman should endeavor, if possible, to so regulate the boiler feed that it is kept going as nearly continuously as possible while maintaining a uniform quantity of water in the boiler, and this, with uniform firing, will give the greatest economy.

When pumps are used to feed with, the amount of the lift of the valves can be regulated by a screw, so as to vary the amount of water the pump will deliver, and in this case it is comparatively easy to set them so that the pump may be kept going without putting too much water in the boiler.

When injectors are used, however, the feed will be intermittent, and a uniform quantity of water in the boiler is best obtained by feeding at short intervals, stopping the feed when the fire door is opened much, as when cleaning the fire.

If the feed water is dirty, the gauge glass should be kept clean by first shutting off the upper cock and opening the lower one, so as to let the water blow through the lower cock, and then shutting off the lower cock from the boiler, and opening the upper one, which will let the steam blow all the water out of the glass. This should be done two or three times a day, so as to keep the holes in the boiler and those in the cocks from closing up with fur or scale.

If the water falls in the glass, or if the gauge cocks show the water to be falling, notwithstanding that the feed pump has been started, it is evident that the pump is not working.

This may occur from a stuck valve, a leak in the suction pipe, from the feed water being too hot, or from the pump failing to start in action from leaky or choked valves.

A stuck valve may generally be relieved by striking a few blows on the outside of the pump with a hammer and a block of wood, or if this does not answer, with the hammer only. Check valves are the ones most likely to stick.

If a pump fails to work by reason of the feed water being too hot, the remedy is to open the pet cock to let the steam out of the pump, but if this does not succeed, cold water may be poured on the outside of the pump, which will start it, after which, in most cases, the pump will keep going and the pet cock may be closed.

If the suction pipe has a joint, a leak there will impair the action of the pump, and, if the leak is great enough, will stop it; the remedy is to make the joint tight.

Plunger pumps sometimes fail to act because the plunger has worn so small in diameter that there is sufficient air between the plunger and the pump barrel to expand and compress without lifting the valve; the remedy is obviously a new plunger of as large diameter as the pump gland will admit of, boring the gland out to admit the new plunger.

All the impurities in the water are left in the boiler when the water has evaporated, and it is obvious these impurities must be blown off or they will form scale on the internal surface of the boiler and the external surface of the tubes or flues.

This scale obstructs the passage of the heat from the iron to the water, and if let get thick enough will cause the iron to rapidly burn out.

To prevent the formation of scale, two principal methods are employed, one being to purify the feed water, and the other to occasionally blow the impurities out of the boiler.

Feed-water heaters generally serve also as purifiers, and their effectiveness is increased in proportion as the water can pass quietly through them, and has a large area on which the impurities can settle. Horizontal heaters have the advantage that they have a large settling area, and a less distance for the impurities to fall through. The water-gauge glass and the lower gauge cock are usually set so as to have a margin of about three inches of water above the tubes or crown sheet of the fire box, hence if it is known that the water is but just below the bottom of the gauge glass or gauge cock, there is no positive danger, although it is improper to let it get so low.

If the water is out of sight, and it is not known exactly how low it is, then it is dangerously low, and every minute is of vital importance.

Should the water get dangerously low in the boiler, the most dangerous thing to do is to lift the safety valve or pump in cold water, especially if it is not known how much water there is in the boiler.

As quickly as possible cover the fire with ashes, coal, earth, sand, or anything that is at hand that will smother the fire, then close the draught to the fire, leaving the fire door and the chimney damper open.

Leave all the steam outlets just as they are, and also the feed.

PRIMING.--Priming, which is also called "foaming," is that the steam carries up water into the steam space. This may arise from several causes, but it is well known that what will stop priming in some cases will cause it in others.

The known causes of priming are--first, too little room for the steam in the boiler, and it follows that a high water level may cause priming; second, it may be caused by a difference of temperature between the water and the steam in the boiler. Suppose, for example, that the pressure of the steam and water in the boiler is 160 lbs. by gauge, and its sensible temperature will be 370 degrees. Suppose then that enough steam is permitted to escape from the boiler to reduce the steam pressure to 140 lbs., and its temperature will be reduced to 361 degrees. But the water will remain at 270 degrees, and the result will be that it will pass into steam so rapidly that it will carry up the water and hold it in suspension among the steam. The water will pass with the steam into the engine cylinder, and the boiler will be said to "prime," "foam," or "work water." The same thing may happen if the water is heated very rapidly.

Priming is wasteful because it rapidly empties the boiler of its water, and dangerous because it may cause the piston to knock out the cylinder head or cover.

When the safety valve blows off, priming may be induced, especially if the engine is at work, because in this case the boiler is being forced, or, in other words, is making steam more rapidly than it is designed to do, and the passage of so large a body of steam through the water is apt to lift it.

Muddy water will sometimes cause foaming or priming, as will also insufficient circulation of the water in the boiler or sometimes the presence of grease or oil.

Priming may be detected from the discharge of water with the steam when the gauge cock is opened, the steam looking white and fluttering as it escapes, and also by violent motion of the water in the gauge glass, or by a thump or pound at the ends of the piston stroke.

To stop priming, the steam from the boiler should be decreased by slackening the speed of the engine, or if necessary, by stopping it. The true water level can then be seen, and if there is too much water in the boiler some of it may be blown off, while if the quantity of water in the boiler will permit it, the feed may be put on.

If the boiler has a surface blow-off cock, or a mechanical boiler cleaner, it is best to blow off from that, as it carries off the scum at the same time as relieving the boiler.

To prevent priming, a steady and uniform rate of boiler feed, the use of pure water, a clean boiler, and steady firing are the best means, turning on the steam slowly so as not to violently disturb the water in the boiler.

The engine as well as the boiler requires attention when the boiler primes. Thus the cylinder cocks should be opened to let out the water from the cylinder and prevent breakage of the cylinder cover.

SCALE IN BOILERS.--The steam leaves behind it all the impurities that the water contained, and these impurities deposit in form of mud and scale, which must be got rid of because it causes a loss of fuel, and if allowed to get thick enough will cause the boiler to burn.

The use of boiler compounds or scale preventatives may be resorted to with advantage, providing they are of a nature to suit the water, but mechanical cleaning must also be resorted to at periods determined by the nature of water.

Boilers are cleaned in two ways--first, by blowing off the impurities before they have formed into scale; and second, by removing at certain intervals whatever scale has formed.

Blowing down may be done in two ways--first, from the surface of the water by means of mechanical cleaners; and second, by blowing out from the bottom of the boiler.

The first draws off the impurities as they are thrown to the surface, the second draws them off after they have become more condensed and sink to the bottom.

How often a boiler should be blown down depends upon the kind of water fed to the boiler; where purifiers are used, less blowing down is obviously needed.

It is best to blow off from the bottom of the boiler when no steam is being used, as during dinner time, letting the water blow down about a quarter of the glass, or from the upper to the middle gauge cock.

As no steam is being used, the feed can then be put on to restore the quantity of water without reducing the temperature of the boiler so much. The feed should be gradual and the fire regulated to keep the steam pressure even.

How often a boiler should be washed out and cleaned depends upon the quality of the water it uses, and varies from about once a week to once a month, according to whether bad and unpurified water or purified water is used.

The first thing to do is to draw the fire, leaving the chimney damper open and closing all the other dampers so that as little cold air as possible can get into the boiler, while the heat can pass away up the chimney.

Let the steam and water all remain in the boiler until there is a gauge pressure of about 5 lbs. in the boiler.

Then open the blow-off cock and let out the water. If the water is blown off under a high pressure, then after the waste is all out the iron is hot enough to dry up the scale, making it hard and very difficult to remove.

After all the water is blown off, take out all the mud plugs and the man-hole and hand-hole covers, and wash out the boiler under as much water pressure as can be had, directing the hose so to reach all parts of the boiler and tubes, and continuing the washing until the water leaves the boiler clean.

Then with a wooden hoe on a piece of gas-pipe of small diameter for a handle, and small enough to pass through the hand-hole, draw all the loose scale to the hand-hole and remove it, letting the water run slowly, so as to carry the small pieces of scale towards the hand-hole as fast as the hoe disturbs it.

Then get inside the boiler, and a few blows with a light ball-pened hammer will loosen the scale, and a steel scraper will remove more, which must be washed down and drawn out with a hoe.

After the cleaning and scaling are complete, the engineer, with lamp in hand, should carefully examine the interior of the boiler and of the fire box, paying especial attention to the stays to see that they are not broken.

The hammer test should also be applied. It consists of sounding the boiler by light blows given by a light ball-pened hand hammer, the sound indicating defective places.