Emerson Process Management 99 - Manual (Page 11)

Type 99
11
8. Four machine screws (key 130) hold both yoke
caps (keys 37 and 116) to the yoke legs (key 31).
Separate these parts to expose the pilot valve.
9. Unscrew the inlet orifice (key 38) to inspect its
seat, the inlet valve plug (key 117), and valve
spring (key 124).
note
Make certain that the yoke assembly is
square with respect to the cross member
of the body casting so that it will not
bind on the body.
10. When reassembling, screw in the inlet orifice all
the way and secure the yoke caps to the yoke
legs. Replace two diaphragm plates, the
diaphragms, and inserts, two more diaphragm
plates, the hex nut, and the relief valve assembly.
11. Assemble the control spring and spring seat
into the body and spring case, being careful
that the diaphragms are free of wrinkles and
properly in place, and evenly installing the cap
screws in a crisscross pattern to avoid placing a
strain on the unit. Install the body flange adapter
with seal washers and cap screws. Install a new
gasket and secure the pilot to the lower casing
with eight cap screws. Set the control spring
according to the adjustment information in the
Startup section.
Converting the Pilot
note
a complete pilot assembly rather than
individual parts may be ordered for
the following conversion procedure.
When a low pressure pilot is ordered
for field conversion of a high pressure
pilot or vice versa, the replacement pilot
assembly comes complete with a pilot
cover (key 132, Figure 9). Remove this
cover before installing replacement pilot
on the existing regulator. The cover can
then be installed on the removed pilot
to form a complete Type 61 (low or high
pressure) pilot for use elsewhere.
When changing one pilot construction (low pressure, high
pressure, or extra high pressure) for another, all parts
attached to the lower casing (key 29, Figure 9) may need
to be replaced with those appropriate for the desired
construction. At the very least, when changing from a
low to high pressure pilot or vice versa, everything below
the lower pilot diaphragm (key 40, Figure 9) except the
cap screws and the hex nut (keys 47 and 13, Figure 9)
will need to be replaced. Actuator and main valve parts
may remain unchanged unless a change in service
conditions requires a change in seat construction, main
spring, or main spring seat. See the Parts List sections
for obtaining the appropriate conversion parts.
Main valve Trim with Disk or O-ring Seat
This procedure is to be performed if inspecting,
cleaning, or replacing trim parts. Part key numbers
for a Type 99 regulator with disk or O-ring seat are
referenced in Figure 9, and part key numbers for
the disk seat unique to the 1000 psig (69,0 bar)
maximum inlet regulator are referenced in Figure 11.
note
all trim maintenance may be performed
with the valve body (key 17, Figure 9
or 11) in the line and with the elbow
(key 23, Figure 9 or 11), pilot supply
tubing (key 24, Figure 9 or 11), and pilot
supply regulator (key 155, Figure 11, if
used) attached to the valve body unless
the valve body itself will be replaced.
1. Disconnect the pilot supply tubing and downstream
control line.
2. Loosen the union nut (key 14, Figure 9) and
remove the lower casing (key 29, Figure 9) with
the cap screw (key 22, Figure 9) or disk and
holder assembly (key 18, Figure 11) on
disassembly or reassembly. A thin-walled socket
may be used to remove the orifice.
3. Access to the disk or O-ring (key 19, Figure 9) can
be gained by removing the cap screw and retainer
(key 21, Figure 9), while on the 1000 psig
(69,0 bar) maximum inlet regulator the entire
disk and holder assembly is removed as a unit.
If necessary, the holder (key 18, Figure 9 or 11) or
adapter (key 157, Figure 11) can be removed by
taking out the cotter pin (key 25, Figure 9 or 11).
4. Install a new body gasket (key 16, Figure 9) and
a new disk, O-ring, or disk and holder assembly
as necessary. Then slide the entire assembly into
the valve body and secure with the union nut.
5. Connect the pilot supply tubing and downstream
control line, then refer to the Startup section for
putting the regulator into operation.