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201/203/205/207 Series Flowmeters and Controllers Instruction Manual
3.7.1.
HFC-203/207 Orifice
To change the orifice in the HFC-203/207 instrument, the valve must be dismantled. Remove the four ¼"
Allen head machine screws in the top of the main valve. Lift off the valve top, exposing the spring and
diaphragm. Note that a small brazed ball bearing is on the downstream side of the valve top. Remove the
spring and diaphragm assembly. The orifice is located at the bottom of the valve body and can be removed
with a 9/16 socket wrench. See the figure on right.
To re-install an orifice, first install the gasket onto
the orifice (replacement gaskets can be obtained
from the factory). Next screw the orifice into the
valve base. Snug up the orifice but do not
overtighten. Place diaphragm assembly into the
base. Line up the two small holes in the diaphragm
with the two small holes in the valve base. Place
the spring on top of the diaphragm. Examine the O-
ring on the valve top for damage if required. Install
the valve top (bonnet), ensuring the bleed screw is
on the upstream side. Tighten down the valve top
evenly to ensure a proper seal at the diaphragm.
EAR99 Technology Subject to Restrictions Contained on the Cover Page
Page 23 of 28
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