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By Westech Industrial Ltd. (in partnership with United Electric Controls)
Rim-seal fires on floating-roof storage tanks can escalate fast. A typical rim-seal fire protection system (RSFPS) detects incipient fire and pressure-discharges an extinguishing agent along the roof perimeter to arrest flame spread. That response hinges on one thing: reliable pressure at the moment of discharge—and a pressure switch you can trust in a cramped, hazardous location.
The application challenge on tank roofs
Tank-top equipment fights for inches. Your fire package has to be compact, yet high-reliability because discharge effectiveness depends directly on pressure. Add in the reality that climbing tanks for upkeep is hazardous and labor-intensive, and you have three competing pressures: space, reliability, and maintenance burden.
The proven answer: UE’s 12 Series pressure switch
For RSFPS OEMs and operators, United Electric Controls’ 12 Series has become a go-to pressure switch because it solves all three constraints:
- All-316 stainless, compact enclosure that fits on agent tanks and instrument panels where real estate is tight.
- Hermetically sealed SPDT/DPDT contacts and a snap-acting Belleville mechanism for vibration resistance, stable setpoints, and long life.
- Hazardous-location approvals (UL, cUL, ATEX, IECEx) with Type 4X / IP66 environmental protection for harsh refinery roofs.
- Dual-seal compliance (ANSI/ISA 12.27.01 & NEC 501.17) to prevent process media from migrating into conduit—no extra sealing hardware or labor.
- SIL 2 certified for use in Safety Instrumented Systems.
Left: Rim Seal Fire Protection System on top of a storage tank – Right: Compact 12 series fitted on extinguishing agent tank
This is precisely why RSFPS manufacturers have standardized on the 12 Series in many installations: it’s compact enough for the tank roof, robust enough for the environment, and proven-in-use for 20+ years, reducing costly service trips.
What this means for your rim-seal system
Space savings: The cylindrical 316SS form factor leaves room for agent tanks, manifolds, and foam hardware—without creative mounting gymnastics.
Reliability at the moment that matters: The switch’s snap-action Belleville disc delivers fast, positive contact transfer despite vibration and temperature swings—maintaining setpoint stability so your agent discharges at the pressure you specify.
Less maintenance on the roof: With sealed contacts and a corrosion-resistant enclosure, routine interventions are minimized—meaning fewer climbs and lower exposure for your team.
Compliance confidence: From Div 1 / Zone 1 approvals to dual-seal requirements and Type 4X/IP66 enclosure ratings, the 12 Series slots into refinery standards without add-ons or workarounds.
Selection quick-guide (12 Series)
When we size a 12 Series for a rim-seal package, we typically look at:
- Setpoint & range: Align the adjustable setpoint with the higher end of the model’s range to minimize deadband on snap-acting mechanisms.
- Process connection & sensor type: 316/316L diaphragms and ¼–½” NPT female options are standard; Hastelloy®/Monel® are available for aggressive media.
- Contacts: SPDT (standard) or DPDT on pressure models; choose gold vs. silver contacts based on your load.
- Conduit & wiring: ½” NPT or M20 with 72″ lead wires for easy routing.
- Mounting: Brackets are available for retrofit to existing agent tanks and rails.
Field-proven on tank roofs
In a recent application, an RSFPS OEM selected the 12 Series as the FPS pressure monitor because of its compact footprint, stainless construction, and proven reliability versus low-cost alternatives—ultimately cutting maintenance and improving system availability.
Why work with Westech
As Westech Industrial, we support fire-protection teams and tank-farm operators across Canada with application engineering, stocking, and startup support for UE’s 12 Series and complementary devices. We help you:
- Specify the correct range and setpoint for discharge integrity
- Match approvals and sealing to site standards
- Streamline mounting/wiring to shorten turnaround
- Build a spares strategy that keeps critical paths covered
Ready to harden your rim-seal fire protection?
Westech can help you evaluate your RSFPS instrumentation and recommend a compact, compliant 12 Series configuration for your tank roofs.
Contact Westech Industrial to discuss your site and get a quotation or demo.
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