t it is difficult to
accurately determine the areas of such small orifices. Further, small
orifices have a tendency to become partly closed by sediment that may be
carried by the steam. The more accurate method of determining the amount
of steam passing through the instrument is as follows:

[Illustration: Fig. 17. Separating Calorimeter]

A hose should be attached to the separator outlet leading to a vessel of
water on a platform scale graduated to 1/100 of a pound. The steam
outlet should be connected to another vessel of water resting on a
second scale. In each case, the weight of each vessel and its contents
should be noted. When ready for an observation, the instrument should be
blown out thoroughly so that there will be no water within the
separator. The separator drip should then be closed and the steam hose
inserted into the vessel of water at the same instant. When the
separator has accumulated a sufficient quantity of water, the valve of
the instrument should be closed and the hose removed from the vessel of
water. The separator should be emptied into the vessel on its scale. The
final weight of each vessel and its contents are to be noted and the
differences between the final and original weights will represent the
weight of moisture collected by the separator and the weight of steam
from which the moisture has been taken. The proportion of moisture can
then be calculated from the following formula:

100 w
x = ----- (7)
W - w

Where x = per cent moisture in steam,
W = weight of steam condensed,
w = weight of moisture as taken out by the separating
calorimeter.

Sampling Nipple--The principle source of error in steam calorimeter
determinations is the failure to obtain an average sample of the steam
delivered by the boiler and it is extremely doubtful whether such a
sample is ever obtained. The two governing features in the obtaining of
such a sample are the type of sampling nozzle used and its location.

The American Society of Mechanical Engineers recommends a sampling
nozzle made of one-half inch iron pipe closed at the inner end and the
interior portion perforated with not less than twenty one-eighth inch
holes equally distributed from end to end and preferably drilled in
irregular or spiral rows, with the first hole not less than one-half
inch from the wall of the pipe. Many engineers object to the use of a
perforated sampling nipple because it ordinarily indicat