• Spring-operated, modulating at low flow
  • Soft seatedFully balanced against backpressure without bellows
  • Pressure assisted drag seal for smooth operation
  • Full lift at 7.5% overpressure
  • Leak tight seating and re-seating
  • Fixed blowdown
  • Integral / full nozzle, 316/316L corrosion resistant trim
  • Packed lift lever available on most sizes


  • Lube oil systems
  • Water systems
  • Chemical processing
  • Thermal relief
  • High-pressure temper quench systems
  • Installations with high outlet backpressures
  • Positive displacement pumps

Service Envelope

Connection Sizes

Larger sizes available on request
½” x 1” - 2” x 3”
(13mm x 25mm - 50mm x 75 mm)

Set Pressure Ranges

See F84L Catalog for orifice specific ratings
30 – 24,277 psig
(2.1 - 1674 barg)

Temperature Ranges

-65 to 525°F
(-54 to 274°C)

Orifice Area Range

.015 – 1.689 in2
(9.7 – 1089 mm2)

End Connections

Custom types available on request
Threaded: NPT, SAE, MS33649/AS5202, AN 37° Flare
Welded: ASME / DIN / API / SAE flanged, Grayloc
Specialty: Swagelok® Tube / VCR, Threaded & Coned

Materials of Construction

Custom available for service or on request
Carbon Steel, Stainless Steel, Monel, Hastelloy C / C22 / C276, Duplex 22% or 25% Cr

Seat/Seal Materials

Custom available for service or on request
Seat Material (Plastic):Teflon®, Ekonol-filled PTFE, Kel-F (PCTFE), PI/PAI (Vespel®, Duratron®, or equal), PEEK

Spindle Seal Material (Elastomer):Buna-N, Viton® (FKM) or equal, EPR/EPDM, FFKM (Chemraz®, Kalrez®, etc), Polyurethane, HNBR