Fire Protection Pressure Relief Valve

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  • UL / ULC Listed
  • Factory Mutual Approved
  • Fast Opening to Maintain Steady Line Pressure
  • Accommodates Wide Range of Flow Rates
  • Closes Gradually for Surge-Free Operation
  • Adjustable Pressure Settings, Not Affected by Pressure At Valve Discharge
  • Now Available in Grooved Ends Sizes 3″-6″

The Cla-Val Model 50B-4KG1 Globe / 2050B-4KG1 Angle
Pressure Relief Valve is designed specifically to automatically
relieve excess pressure in fire protection pumping systems.
Pilot controlled, it maintains constant system pressure at the
pump discharge within very close limits as demands change.
The 50B-4KG1 and 2050B-4KG1 can be supplied with optional
internal and external epoxy coating of the main valve wetted
surfaces. On ductile iron valves, epoxy coating is standard.

Type Approved

UL / ULC Listed . . . . . . . . . . Sizes 3″ thru 8″
FM Approved . . . . . . . . . . . . Sizes 3″ thru 8″

Typical Application

"Fluid Control at Its Best"

Operation Sequence

At pump start, Cla-Val Relief Valve modulates to relieve
excess pump capacity, maintaining positive system pressure
at the pump discharge.
When fire demand slows or ceases, Cla-Val Model 50B-4KG1
opens, diverting entire pump output to discharge, allowing fire
pump to be stopped without causing surges in the lines.
Please note that if the Model 50B-4KG1 is to be used on a
continuous duty basis to maintain fire-system pressure, suitable back pressure must be provided on the valve to prevent
cavitation damage. Consult the factory for details.
For anti-cavitation model, see E-50B-4KG1KOl.

Optional UL Listed Materials for Seawater and Severe Service Applications:

  • Nickel Aluminum Bronze (NAB) – ASTM B148 Alloy C95800
  • Monel – QQ-N-288 Comp B – ASTM A494 Grade M30H
  • Cast Steel – ASTM A216 Grade WCB
  • 316 Stainless Steel – ASTM A743 Grades CF3M and CFM8
  • Super Austenitic Stainless Steel – ASTM A351 Grade CK3MCuN (SMO 254)
  • Super Duplex Stainless Steel – ASTM A890 Grade 5A (CE3MN)

Typical Application

Valve Capacity

All Sizes UL, FM and ULC

Model 50B-4KG1 Globe

Model 2050B-4KG1 Angle

We recommend providing adequate space around valve for maintenance work.

Specifications

Standard Materials

Main Valve Body & Cover
Ductile Iron ASTM A536 Grade 65-45-12
Standard Main Valve Trim:
Stainless Steel Seat
Stainless Steel Dura-Kleen Stem
Standard Pilot Control System:
Cast Bronze with
Stainless Steel Trim

Pressure Ratings

Class 150 (250 psi Max)
Class 300 (300 psi Max)
Water, to 180°F Max

End Details

150, 300 ANSI B16.42 and Grooved Ends

Sizes

Globe: 3″ – 8″ flanged or grooved
Angle: 3″ – 8″ flanged
Angle: 3″ – 6″ grooved

Standard Materials

Available in the Following Relief
Pressure Ranges:
20-200 psi (150 Class)
100-300 psi (300 Class)

Specifications

Sizes

Globe: 3″ – 8″ flanged or grooved
Angle: 3″ – 8″ flanged
Angle: 3″ – 6″ grooved

Consult factory for flange ratings.
See page 1 for seawater service materials options.