DFT® Vacuum Breakers provide effective protection against collapse of pressure vessels, tanks and rolls. They prevent condensate "back-up" when equipment is shut down or inlet steam is reduced by modulating control valves. In piping systems, DFT® Vacuum Breakers are used to break siphons, prevent pipe collapse during transient pressure drops, and to provide addition of air on the downstream side of check valves to dampen water hammer.
Unit of Measure

Specifications

Series

N/A Vacuum Breaker

Style

N/A BSSV

Size

N/A DN 25
1 in

Nominal Size (MNPT) A

N/A 1.00 in

Unthreaded Inlet Bore B

N/A 0.56 in
14 mm

Cv

N/A 5.8

Friction Loss (Feet of Pipe)

N/A 7

Friction Loss (Meter of Pipe)

N/A 2.1
Valve Cracking Pressure1 N/A 0.60 psi
0.041 bar
16.7 in.water
424 mm.water
31.1 mmHg

Valve Cracking Pressure Tolerance

N/A ±10%

Approx. Net Weight Each

N/A 0.38 lb
0.2 kg
Cold Working Pressure2
N/A 0 psig
2500 psig
0 barg
172 barg

Materials of Construction

Seat

N/A 303 SS

Disc

N/A 316 SS

Guard

N/A 303 SS

Spring

N/A 316 SS

Retaining Ring

N/A 316 SS

Soft Seat Materials

Soft Seat Materials3 N/A Buna-N (-70 to 250°F)
EPDM (-75 to 300°F)
TFE®-Viton (-40 to 400°F)
Viton® (-40 to 400°F)
Zelon® (37 to 400°F)

Springs

Springs

N/A Inconel® X-750 (-460 to 700°F)
316 SS (-460 to 450°F)

Valve Selection Specifications

ENDS

N/A NPT

ASME

N/A 2500 CWP

Materials

N/A 303 SS

Codes and Standards

ANSI

N/A B1.20.1

MSS

N/A SP-25

Options

N/A Inconel® 750 Spring
Soft Seat

Features

N/A

  • 1" to 4" size
  • 450 to 6000 CWP
  • Threaded O.D. (MNPT)
  • Unthreaded inlet bore
  • Stainless Steel Construction
  • Spring-assisted silent closing
  • Horizontal or vertical installation
  • Tight shut-off - lapped disc & seat
  • Easy maintenance
  • Versatile

Options

N/A

  • Inconel® 750 Spring
  • Soft seat

  • 1 Cracking pressure for vertical flow will be slightly different: upward flow, slightly higher; downward flow, slightly less.
  • 2 Contingent on service ratings of matching pipe and fittings.
  • 3 Buna-N and Viton are not suitable for steam service.