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OPW 178S Series External AST Emergency Shut-Off Valve

The OPW 178S Series External AST Shut-Off Valve is designed to shut off product flow from an aboveground storage tank, bulk loading rack or any place in the fuel supply line in the event of a fire. The 178S installs in-line on fuel supply piping. A fusible link attached to a spring-operated lever holds the poppet normally open. In the event of a fire, the fusible link melts at 160°F, allowing the spring-actuated poppet to shut off the flow of product in the fuel supply line. The 178S is available in 2" female NPT connections.

178S Valve (Open Position)


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  • Viton® Main Disc - Compatible with gasoline, diesel, kerosene, ethanol, methanol, MTBE, fuel oil, mogas, motor oil and various other blends of fuel.
  • Full-Bore Inside Diameter for Superior Flow Rates - Maximizes flow rates in the fuel supply lines.
  • Easy Service Entry - Threaded cap assembly allows removal, replacement or servicing of the carrier, disc or disc holder.
  • Rated Normal Pressure Limit - 125 psi (8.6 bar).
  • Cold Non-Shock Pressure Limit - 200 psi (13.8 bar)
  • Temperature Limit - 225° F


  • Body: cast iron
  • Seat ring: brass
  • Disc: Viton®
  • Cap: bronze

Ordering Specifications

Product # in. mm lbs. kg
178S-6130 2 51 5.35 2.43


in. mm
A 5-17/32 140
B 3-1/16 78
C 3-1/16 62

Replacement Parts

Key Part No. Description
1 H05973M Spring
2 H12070M O-ring (Viton®)
3 H7635RB Packing Nut
4 H10445M O-ring (Viton®)
5 H01344M Fusible Link Sub-Assy
6 H01505RB Pin
7 C01533RB Stem
8 H07644M Set Screw
9 H07642ZA Lever
10 H03295M Washer
11 H04035M Disc Nut
12 H12071R Disc (Viton®)
13 H10004A Disc Holder
14 H11293M Compensating Ring
15 C03144M Carrier
16 H11547DI Cap
17 H10003M Retaining Ring

Feaures & Benefits

  • Pre-Engineered turn key system
  • Environmentally safe Double wall systems
  • Portable- Lifting lugs set up for future relocation
  • Factory installed components- system ships fully assembled, just provide power
  • Spill Containment- Built in spill containment for fill and dispenser
  • Fire Resistent or Protected Tanks UL142 & UL2085
  • Custom Sizes from 250 gallons to 30,000 gallons
  • Single or Dual product tanks
  • Systems set up for gas, diesel, E-85, Jet-A, Avgas, Oil, lube & Chemical
  • Multiple options for pumps or dispensers to match your needs

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Our engineered systems are delivered to you completely assembled and ready to deploy for use, simply attach to a power source or you can upgrade to our totally self contained, self powered top of the line FleetFuel Tank System which is used by our military in combat zones and emergency fueling situations around the globe. Our system is trusted by the United States Military, FEMA, and some of the worlds’ largest corporations because of its rugged construction, reliability, embedded technology and the fact that our systems are engineered to be fire and ballistic rated if necessary.