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REPORT OF PROJECTION COMMITTEE*
VENTILATION OF LAMPHOUSE AND RHEOSTAT ROOMS
In its initial report to the Society last Spring the Projection Committee stated that the ventilation section of the report was far from complete, but promised to go more thoroughly into the matter in the succeeding six months.
Some progress has been made, but the section is still incomplete. No definite data has been secured regarding the volume of smoke and gas that may be expected in the case of a film fire. Until this is done all recommendations as to the ventilation necessary to remove these fumes would be purely guesswork.
With regard to the ventilation of the lamphouses and rheostat room, however, the problem is much more simple. Starting with the reasonable assumption that the vent flue temperature should not exceed 300 °F., it becomes merely a problem of calculating the air volume necessary to carry away the wattage dissipated at the temperature rise of 230°F.
Considering the case of the large de luxe theater, it is not unreasonable to assume that within a few years the connected load will be about as follows:
4 H. I. Arcs, each 150 amps, and 80 volts 48,000 watts
2 Stereo Arcs, each 50 amps, and 50 volts 5,000 watts
2 Effect Arcs, each 100 amps, and 60 volts 12,000 watts
2 Spot Arcs, each 100 amps, and 60 volts 12,000 watts
Total 77,000 watts
It is, of course, not likely that all of this load will be connected at any one time, but the draft adjustment for best results is quite critical; consequently, it is impractical to install a system having capacity less than sufficient to care for all equipment simultaneously. Such a system then should be capable of removing 77,000 watts continuously with a temperature rise of 230°F. This 77,000 watts is equivalent to 4380 Btu. per minute and, assuming a temperature rise of 230° F. and a specific heat of 0.25 for the flue gas, we find the
* October, 1929. 444