Maintenance; Main Valve - Emerson Fisher OS2 Instruction Manual

Type OS2
Because the Type OS2 mounted on the
Types 627-OSX, EZH-OSX, EZL-OSX and
EZR-OSX is turned 180°, the following
directions apply to the Type OSE only,
however, the reset procedure for the
Types 627-OSX, EZH-OSX, EZL-OSX
and EZR-OSX is the same. When a
specific direction is given (i.e. top left),
the Types 627-OSX, EZH-OSX, EZL-OSX
and EZR-OSX direction will be reversed
(i.e. bottom right).
To reset the Type OS2, close the upstream block valve.
Open the front cover of the mechanism box.
Detection Stage (First Stage)
The reset pin with white dot is at the top center location of
the mechanism box, see Figure 8. Push this pin up and to
the right (Type OSE only, see note above). This action will
lock in the detection stage (see step A in Figure 7).
Power Stage (Second Stage)
The reset tool (key 3) is keyed and will only
fit on the second stage releasing shaft in one
orientation. Be sure the tool securely fits
onto the shaft before turning.
To reset the power stage, use the square reset tool (key 3)
located on the lower left corner of the mechanism box. Place
the square end of the tool on the second stage releasing
shaft at the center of the box and slowly rotate clockwise
(see step B in Figure 7).
When movement is started on the stem, the internal bypass
in sizes from NPS 1 through 6 / DN 25 through 150 will open
and equalize the pressure on each side of the valve plug
before the valve plug can be moved off the seat. For NPS 8
and 10 / DN 200 and 250, external bypass valve (key 97)
should be opened.
CAUTION
Wait for the pressure on each side of the
valve plug to equalize before proceeding to
the following steps. Never use an extension
with the reset tool when resetting the
second stage. Failure to do so may result in
equipment damage.
After the pressure has equalized on each side of the valve
plug, continue turning the reset tool. This action will raise the
valve plug, compress the closing spring and latch the second
stage (power stage) mechanism. Replace the reset tool on
its holder and replace the cover. Slowly open the upstream
block valve.
*For further instructions on Types 627, EZR, EZH and EZL, refer to the corresponding instruction manual of these products.
10
Note
Note
Shutdown*
WARNING
!
To avoid personal injury or property damage
due to explosion or damage to shutoff
device, regulator or downstream components
during shutdown, release downstream
pressure to prevent an overpressure
condition on the regulator diaphragm.
Installation arrangements may vary, but in any installation it
is important that the valves be opened or closed slowly. The
steps below apply to the typical installation.
1. Slowly close the downstream shutoff valve.
2. Slowly close the upstream shutoff valve.
3. Slowly open the vent valves downstream of the
slam-shut valve.
4. Slowly open the vent valves upstream of the
slam-shut valve.

Maintenance

Instructions are given for complete disassembly and
assembly. Key numbers are referenced in Figure 12 for
NPS 1 through 6 / DN 25 through 150 body sizes and
Figure 13 for NPS 8 and 10 / DN 200 and 250 body sizes
unless otherwise noted.
WARNING
!
Avoid personal injury or damage to
property from sudden release of pressure
or uncontrolled gas or other process fluid.
Before disassembling, carefully relieve
all pressures. Use gauges to monitor
inlet and outlet pressures while releasing
these pressures.
The seat ring on the Type OSE is pressed
into the body and is not field removable.

Main Valve

Disassembly for NPS 1 through 6 / DN 25 through
150 Body Sizes (Refer to Figure 12)
The position of the travel stop (Figure 13)
depends on the Type of assembly and
body size. The travel stop must be in the B
position (Figure 12) for NPS 1 and 2 / DN 25
and 50 body sizes. For all other body sizes,
the travel stop must be in the C position
(Figure 12).
Note
Note