RV, RL and RM Series

FITOK relief valves open when systems pressure reaches the set pressure and close when system pressure falls below the set pressure.


  • Working Temperature: -40°F to 300°F (-40°C to 148°C)
  • Variety of end connections
  • Liquid or gas service
  • Adjustable bonnet cap and adjustable set pressure
  • Lead seal lock wire through lock wire holes to lock proportional relief valve so as to secure a set pressure effectively
  • Variety of seal materials
  • Label identifies the set pressure range

Set Pressure:

  • RV Series: 7 colour-coded springs available for a wide range of set pressures, 50 to 6000 psig @ 70°F (3.4 to 414 bar @ 20°C)
  • RL Series: 10 to 225 psig @ 70°F (0.68 to 15.5 bar @ 20°C)
  • RM Series: 3 colour-coded springs available for a wide range of set pressures, 50 to 1500 psig @ 70°F (3.4 to 103 bar @ 20°C)

Maximum Outlet Pressure:

  • RV Series: 1500 psig (103 bar)
  • RL Series: 225 psig (15.5 bar)
  • RM Series: 1500 psig (103 bar)

Orifice Size:

  • RV Series: 0.14″ (3.6 mm)
  • RL Series: 0.19″ (4.8 mm) and 0.25″ (6.4 mm)
  • RM Series: 0.25″ (6.4 mm)

Back Pressure

  • Back pressure is the pressure of the outlet of valves. It increases the set pressure of proportional relief valves.
  • RV and RM Series: balanced stem design to eliminate the effect of the system back pressure.
  • RL Series: Pre-set pressure = Desired pressure – 0.8 x back pressure


Relief valves are proportional relief valves that open gradually as the pressure increases. Consequently, they do not have a capacity rating at a given pressure rise, and they are not certified to ASME or any other codes. Some system applications require relief valves to meet specific safety codes. The system designer and user must determine when such codes apply and whether these relief valves conform to them. FITOK proportional relief valves should never be used as ASME Boiler and Pressure Vessel code safety relief devices. FITOK proportional relief valves are not “Safety Accessories” as defined in the Pressure Equipment Directive

Pressure-Temperature Rated Value

Set Pressure and Resealing Pressure

Set pressure: the set pressure is the upstream pressure at which the first indication of flow occurs. The repeatability of set pressure of each valve after initial relief is ±5% at room temperature. From 60 to 80°F (15 to 26°C), ±3.0 psig (0.20 bar) or ±5% of the initial set pressure (whichever is higher). Below 60°F (15°C) and above 80°F (26°C), ±6.0 psig (0.40 bar) or ±20% of the initial set pressure (whichever is higher). Resealing pressure: the resealing pressure is the upstream pressure at which there is no indication of flow. Resealing pressure is always lower than set pressure. For valves not actuated for a period of time, the initial relief pressure may be higher than the set pressure.

SeriesTest Set Pressure psig (bar)Percentage of the Set pressure as the Minimum Resealing Pressure, %
Rl10 to 20 (0.7 to 1.3)
175 to 225 (12.0 to 15.5)
RV/RM100 to 200 (6.8 to 13.7)
850 to 1000

Ordering Number Description

The “Ordering Number Description” is a reference to understand the combination rules of FITOK product part number. Not all combinations are available. Standard thread pitch for metric threads are as follows: M10 and below – 1 mm, M12 to M24 – 1.5 mm, M27 and above – 2 mm. Standard thread pitch should be ignored in the ordering number, others should be specified. Cleaning and Packaging: FC-01 = standard cleaning and packaging for general industrial procedures. FC-02 = special cleaning and packaging for wetted components to ensure compliance with product cleaning requirement of ASTM G93 Level C. For proportional relief valve with a specified set pressure and a nameplate , set pressure value can be added as suffix to the part number. The set pressure value should be within the set pressure range of the selected spring, and the following requirements should be followed;