ESI Technologies Group
The Fisher MR98 series is used for backpressure or relief applications in liquid, gas, air, and steam service. The Types MR98L, MR98H, and MR98HH are direct-operated and spring-loaded. The Types MR98LD, MR98HD, and MR98HHD use additional pressure loading to maintain relief differential pressures, backpressures or for remote setpoint adjustment.
Available Backpressure Constructions
MR98L: 2 to 38 PSIG / 0.14 to 2.6 bar set pressure range
MR98H: 15 to 200 PSIG / 1.0 to 13.8 bar set pressure range
MR98HH: 150 to 375 PSIG / 10.3 to 25.9 bar set pressure range
Available Pressure Differential Constructions
MR98LD: 2 to 38 psi / 0.14 to 2.6 bar set pressure range; max differential 150 psi / 10.3 bar
MR98HD: 15 to 200 psi / 1.0 to 13.8 bar set pressure range; max differential 300 psi / 20.7 bar
Available High-Pressure Differential Constructions
MR98HDP: 15 to 200 psi / 1.0 to 13.8 bar set pressure range; max differential 600 psi / 41.4 bar
MR98HHD: 150 to 375 psi / 10.3 to 25.9 bar set pressure range; max differential 400 psi / 27.6 bar
Body and Spring Case Materials
Gray Cast Iron
WCC Steel
LCC Steel
Stainless Steel
Special Alloys: Monel®, Hastelloy® C, Aluminium-Bronze
Body Size and End Connection Styles
1/4-inch
1/2-inch / DN 15
3/4 and 1-inch / DN 20 and 25
1-1/2 and 2-inch / DN 40 and 50 (not available for Types MR95L and MR95LD)
End Connection Styles
NPT, SWE, and Welded and Integral CL150 RF, CL300 RF, CL600 RF, and PN 16/25/40 RF; all with 14-inch face-to-face (EN flanged-356 mm face-to-face)
Maximum Inlet Pressure
600 PSIG / 41.4 bar
Maximum Outlet Pressure
400 PSIG / 27.6 bar
Pressure Registration
Internal or External
MR98H Series Approximate Weights
1/4 NPT body: 5 lb / 2.3 kg
1/2-in / DN 15 body: 10 lb / 4.5 kg
3/4 and 1-in / DN 20 and 25 bodies: 22 lb / 10 kg
1-1/2 and 2-in bodies / DN 40 and 50: 55 lb / 25 kg
MR98L Series Approximate Weights
1/4 NPT body: 7 lb / 3.2 kg
1/2-in / DN 15 body: 15 lb / 6.8 kg
3/4 and 1-in / DN 20 and 25 bodies: 35 lb / 16 kg
Typical applications include control and maintenance of backpressure on pumps, the differential pressure across lubricated seals, steam header pressure, fuel and oil lines pressure, air supply systems pressure, pump bypass applications for API general and special purpose lube and seal oil systems, relief applications for flash tanks and accumulators and other process and industrial uses.
