The plants contained in the two power-houses were almost identical, there being only slight differences in the details of arrangement due to local conditions. A list of the main items of the plant at one power-house is shown in [Table 2].
TABLE 2.—Plant at One Power-House.
| No. of items | Description of item. | Cost. |
|---|---|---|
| Three | 500-h.p. water-tube Sterling boilers | $15,186 |
| Two | Feed pumps, George F. Blake Manufacturing Company | 740 |
| One | Henry R. Worthington surface condenser | 6,539 |
| Two | Electrically-driven circulating pumps on river front | 5,961 |
| Three | Low-pressure compressors, Ingersoll-Sergeant Drill Company | 33,780 |
| One | High-pressure compressor, Ingersoll-Sergeant Drill Company | 6,665 |
| Three | Hydraulic power pumps, George F. Blake Manufacturing Company | 3,075 |
| Two | General Electric Company's generators coupled to Ball and Wood engines | 7,626 |
| Total cost of main items of plant | $79,572 | |
| Sumary of Cost of One Plant. | ||
| Total cost of main items of plant | $79,572 | |
| Cost of four shields (including installation, demolition, large additions and renewals, piping, pumps, etc.) | 103,560 | |
| Cost of piping, connections, drills, derricks, installation of offices and all miscellaneous plant | 101,818 | |
| Cost of installation, including preparation of site | 39,534 | |
| Total prime cost of one power-house plant | $324,484 | |
The following is a short description of each item of plant in [Table 2]:
Boilers.—At each shaft there were three 500-h.p., water-tube boilers, Class F (made by Sterling and Company, Chicago, Ill.). They had independent steel stacks, 54 in. in diameter and 100 ft. above grate level; each had 5,000 sq. ft. of heating surface and 116 sq. ft. of grate area. The firing was by hand, and there were shaking grates and four doors to each furnace. Under normal conditions of work, two boilers at each plant were able to supply all the steam required. The average working pressure of the steam was 135 lb. per sq. in.
The steam piping system was on the loop or by-pass plan. The diameter of the pipes varied from 14 in. in the main header to 10 in. in the body of the loop. The diameter of the exhaust steam main increased from 8 in. at the remote machines to 20 in., and then to 30 in., at the steam separator, which in turn was connected with the condensers. A pipe with an automatic relief valve from the exhaust to the atmosphere was used when the condensers were shut down. All piping was of the standard, flanged extra-heavy type, with bronze-seated gate-valves on the principal lines, and globe-valves on some of the auxiliary ones. There was an 8-in. water leg on the main header fitted with a Mason-Kelly trap, and other smaller water traps were set at suitable intervals.
PLATE XXIX.
TRANS. AM. SOC. CIV. ENGRS.
VOL. LXVIII, No. 1155.
HEWETT AND BROWN ON
PENNSYLVANIA R. R. TUNNELS: NORTH RIVER TUNNELS.
