549
OF ENGINEERING FORM ULÆ.
Experiments on Steam Jets.
(Siemens, ‘Trans. Ihst. Meeh. Engrs.,’ 1872.)
Compression of air into a closed vessel 225 cube feet capacity.
Pressure of steam in steam boiler, 50 lbs. per square inch.
Pressure of air in inches of mercury.
Area of
Circular
Orifice.
Time of Action of Jet in Minutes.
8.
•07*
•12*
•Off
JO
9
11
12
12
14
13 I3f 14 i
16 19 121+
15 15i 16 J 16f 16f i 12
15
24
151
25
15
24i
14J
241
Hi
23|
14j
, 231
101I 10
6
9
3
4
5
6
* With condensing water. -j- Without condensing water.
Final temperature of air in vessel: 1st experiment, 113° Ft.
2nd, 158° Ft.
Exhaustion from closed vessel, 225 cube feet capacity.
Pressure in steam boiler, 45 lbs. per square inch. Vacuum
in inches of ihercury.
Area of Circular Orifice. Sq. Ins. Time of Action of Jet in Minutes.
1 2 3 4 5 6 7
•05 9 13 14i 151 15} — —
•10 10 13i 15 154 15^ — —
•15 9i 13-i ] 6| 1U 18 J8i
•20 * 13 15| 17 174 18i 18i
1. The quantity of air delivered by a steam jet depends on
the extent of surface contact between stir and steam up to the
limits of exhaustion aud compression the jet is capable of
producing.
2. The maximum degree of vacuum or pressure attainable
increases in direct proportion to the steam pressure employed.
3. The quantity of air delivered per minute within effective
limits is in inverse proportion to the weight of the air acted
upon. Better result is obtained in exhausting than in com-
pressing.
4. The limits of air pressure attainable with a given pressure
of steam are the same in compressing and exhausting within
the limit of a perfect vacuum in the latter case.