Emerson Fisher MR98 Series - Overpressure Protection; Parts List

MR98 Series
4
Note
It is important that the relief valve or
backpressure regulator be installed
so that the vent hole in the spring
case is unobstructed at all times. For
outdoor installations, the relief valve
or backpressure regulator should be
located away from vehicular tra󰀩c and
positioned so that water, ice and other
foreign materials cannot enter the spring
case through the vent. Avoid placing the
relief valve or backpressure regulator
beneath eaves or downspouts and be
sure it is above the probable snow level.
Overpressure Protection
Maximum inlet pressure depend upon body materials
and temperatures. See Specications section or the
maximum inlet pressure of the valve and the maximum
spring case loading pressures stamped on the
nameplate of Types MR98LD, MR98HD, MR98HDP
and MR98HHD. The valve should be inspected for
damage after any overpressure condition. Fisher™
relief valve or backpressure regulators are NOT
ASME safety relief valves.
Startup
The relief valve or backpressure regulator is factory
set at approximately the midpoint of the spring range
or the pressure requested, so an initial adjustment
may be required to give the desired results. With
proper installation completed and relief valves properly
adjusted, slowly open the upstream and downstream
shuto󰀨 valves (if applicable).
Adjustment
To change the control pressure, remove closing
cap or loosen the jam nut and turn the adjusting
screw clockwise to increase control pressure or
counterclockwise to decrease pressure. Monitor
the control pressure with a test gauge during the
adjustment. Replace closing cap or tighten the jam nut
to maintain the desired setting.
Taking Out of Service (Shutdown)
▲
WARNING
To avoid personal injury resulting
from sudden release of pressure,
isolate the relief valve or backpressure
regulator from all pressure before
attempting disassembly.
Parts List
Key Description
1 Body
2 Spring Case
3* Orice
4* Valve Plug
5 Bottom Plug
7 Valve Plug Guide
8 Lower Spring Seat
9 Upper Spring Seat
10 Pusher Post
11 Control Spring
12* Diaphragm (2 required for metal, FKM and EPDM diaphragms)
13 Nameplate
14 Diaphragm Protector (not shown)
15 Adjusting Screw
16 Cap Screws
Types MR98L and MR98LD
1/4 NPT; DN 15 / 1/2 in. bodies - 10 required
DN 20 and 25 / 3/4 and 1 in. bodies - 12 required
Types MR98H, MR98HD, MR98HH, MR98HDP and MR98HHD
1/4 NPT body - 6 required
DN 15 to 50 / 1/2 to 2 in. bodies - 8 required
17 Jam Nut
18 Drive Screw (4 required)
19* Diaphragm Gasket (2 required for pressure loaded spring case)
21 Diaphragm Head
22 Adjusting Screw Assembly
23 Handwheel (not shown)
24 Machine Screw
25 O-ring Retainer
25 Seat Retainer
28 Lockwasher
29* Gasket
31 Locknut
32 Stu󰀩ng Box
*Recommended Spare Part
33 Adjusting Screw
34 Packing Follower
35 Stu󰀩ng Box Nut
36 Packing V-Ring (3 required)
37* Stu󰀨 Box Gasket
38 Handwheel / Handle
39 Internal Adaptor
40 External Adaptor
41 Machine Screw
41 Jam Nut
42 Spring
43 Washer
44 Washer
45* O-ring
47 NACE Tag (not shown)
48 Tag Wire (not shown)
49 Lockwasher (not shown)
50* Sealing Washer
51 Vent (not shown)
52 Plug
53* Valve Plug O-ring
57 Jam Nut (not shown)
58 Washer
59* O-ring
59* L-ring
62 Adaptor (not shown)
63* Bottom Plug Seal
64 Flow Arrow
65 Pipe Plug (not shown)
66 Pressure Gauge (not shown)
68 Restriction (not shown)
69 ATEX Tag (not shown)
70 PED Tag (not shown)
Key Description