Western Electric 407A-4, Инструкция по эксплуатации

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to the cover plate of the low-pressure chamber and extending
down into the mercury. The volume of this "stick" is s o
distributed that the dis placement o f mercury at any point
wil l be such as to produce the proper reading on the chart .
THEREFORE, FOR ANY GIVEN POSITION OF THE INDICATOR ARM
THERE IS ONE POS ITION ONLY OF THE MERCURY IN THE TWO LEGS
OF THE 11U11 TUBE TO GIVE THE CORRECT READING FOR THE CORRE­
SPONDING DIFFERENTIAL.
For this reason it is vitally important in s etting up
the instrument and putting it into calibration that the cor ­
rect quantity of mercury b e put into the chambers . Foll ow
these instructions very caref'ully. Remove needle point
s crew in center of fill ing plug
(
s ee Fig. 10) . Pour mer­
cury into instrument through open filling plug until pen
rests s l ightly below z ero line . It is well to rap instru­
ment wfth the hand during this operation to insure the
prompt s ettling of the mercury. Replace s crew in filling
plug.
Filling Chambers and Piping with Water
Close L . H. and R. H. valves on manifold .
Open center valve on manifold.
Open bleeder valves on top of vapor traps .
Remove plug from high-pressure chamber and fill chamber
with water . Replace plug.
Remove plug from low-pressure chamber and fi ll chamber
with water . Replace plug.
With L.H. and R. H. valves on manifold c l os e d, s tart
water c irculating through the venturi .
Close center valve on manifold.
Crack L.H. valve and b leed air from top of L. H . vapor
trap. Close L.H. blee der and L. H. valve .
Open center valve on manifold.
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