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Big Hermet Explosion-Proof Hermetically Sealed Pressure Switch (BL / U8 Series)

Name: Big Hermet Explosion-Proof Hermetically Sealed Pressure Switch (BL / U8 Series)
Brand: SOR

The SOR Big Hermet Explosion-Proof Hermetically Sealed Pressure Switch (BL Housing / U8 Diaphragm Series) is an ultra-rugged, agency-certified pressure control instrument engineered for hazardous industrial environments, oil refineries, offshore platforms, chemical processing plants, and power generation facilities. Utilizing SOR's field-proven Static O-Ring force-balance sensing architecture paired with an all-welded U8 fire-safe diaphragm and a hermetically sealed steel capsule snap switch, the entire unit carries UL Listing and CSA Certification for Class I, Groups A, B, C, D and Class II, Groups E, F, G; Divisions 1 & 2. The U8 fire-safe diaphragm system integrates the sensing diaphragm, cylinder disc, and pressure port into a single continuous weld tested to survive 1,900 °F flames for 30 minutes at rated overrange pressure without rupture or leakage. Equipped with external calibration adjustments that permit set point tuning in the field without declassifying the hazardous area or disconnecting electrical power, SIL 2 functional safety certification according to IEC 61508, and backed by SOR's 3-year limited manufacturer warranty.

Full unit UL Listed and CSA Certified for Class I, Groups A, B, C, D and Class II, Groups E, F, G, Divisions 1 & 2 hazardous locations

Hermetically sealed steel capsule protects SPDT/DPDT switching contacts from corrosive atmospheres, moisture, and hydrogen sulfide

Patented U8 fire-safe welded diaphragm system survives direct flame exposure at 1,900 °F (1,038 °C) for 30 minutes under rated overrange pressure

Field-adjustable set point with self-locking adjustment nut allows calibration without declassifying the hazardous area or opening enclosures

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Big Hermet Explosion-Proof Hermetically Sealed Pressure Switch (BL / U8 Series)

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Operating Pressure Ranges30 in Hg Vac to 7,000 psi (1 bar Vac to 480 bar) across 15 piston/spring spans

Repeatability±1% of full adjustable span

Explosion-Proof CertificationUL Listed / CSA Certified Class I, Groups A, B, C, D; Class II, Groups E, F, G; Div 1 & 2

Enclosure Ingress RatingNEMA 4, 4X, IP65 (Copper-Free 356 Cast Aluminum BL Housing)

Switching CapsuleHermetically sealed steel capsule (KB SPDT: 15A @ 250 VAC, EB DPDT: 5A @ 250 VAC, JR/JB Gold)

Fire-Safe DiaphragmU8 Welded Fire-Safe Diaphragm in 316SS (1,900 °F / 30 min flame-tested per US Patent 4,438,305)

Process Connection1/2" NPT Female standard (1/4" NPT Female optional) in 316SS, Monel, or Hastelloy

Conduit Connection3/4" NPT Female with 18" 18 AWG color-coded wire leads (or optional TB junction box)

Ambient Temperature-40 °F to 167 °F (-40 °C to 75 °C)

Safety Integrity LevelIEC 61508 SIL 2 Certified for SIS loops

Standard WarrantySOR 3-Year Limited Manufacturer Warranty

Engineering Specifications & Ordering Matrix

SOR Big Hermet Explosion-Proof Pressure Switch Technical Guide

Select your piston/spring range, switching element, fire-safe diaphragm metallurgy, process port connection, and optional accessories for hazardous location service.

Operating Range30 in Hg Vac to 7,000 psi (480 bar)

Hazardous RatingClass I, Groups A, B, C, D; Div 1 & 2

Diaphragm SystemU8 Fire-Safe Welded (1,900 °F / 30 min)

Safety IntegritySIL 2 Certified / UL & CSA Listed

Piston & Spring Adjustable Range Selection

12-4Piston 12, Spring 4: 0.5 to 6 psi (35 to 415 mbar) [Proof 400 psi / 27 bar]

4-4Piston 4, Spring 4: 2 to 25 psi (0.14 to 1.7 bar) [Proof 1,000 psi / 70 bar]

6-3Piston 6, Spring 3: 12 to 100 psi (0.8 to 7 bar) [Proof 2,500 psi / 175 bar]

5-3Piston 5, Spring 3: 25 to 240 psi (1.7 to 16 bar) [Proof 6,000 psi / 410 bar]

9-5Piston 9, Spring 5: 200 to 1,000 psi (14 to 70 bar) [Proof 6,000 psi / 410 bar]

9-45Piston 9, Spring 45: 200 to 1,750 psi (14 to 120 bar) [Proof 6,000 psi / 410 bar]

1-45Piston 1, Spring 45: 500 to 4,000 psi (35 to 275 bar) [Proof 6,000 psi / 410 bar]

Explosion-Proof Housing

BLUL Listed / CSA Certified Explosion-Proof Housing for Class I Div 1 & 2, Groups A, B, C, D (Copper-free aluminum, NEMA 4X, IP65)

Hermetically Sealed Switching Element

KBSPDT Hermetically Sealed Capsule: 15A @ 250 VAC, 0.4A @ 125 VDC, 5A @ 30 VDC

EBDPDT Hermetically Sealed Capsule: 5A @ 250 VAC, 0.5A @ 125 VDC, 5A @ 30 VDC

JRSPDT Gold Contacts for low-power digital DCS/PLC circuits: 1A @ 125 VAC, 1A @ 28 VDC

JBDPDT Gold Contacts for low-power digital DCS/PLC circuits: 1A @ 125 VAC, 1A @ 30 VDC

Diaphragm System (Wetted Parts)

U8U8 Fire-Safe Welded Diaphragm System in 316SS (Survives 1,900 °F for 30 min, required for full UL/CSA listing)

U9U9 Welded Metal Diaphragm in 316SS, Monel, or Hastelloy C (No elastomer O-ring)

U7U7 Welded Flush Diaphragm in 1" NPT(M) 316SS for viscous media and slurries

Pressure Port Connection & Material

C2A1/2" NPT Female, 316 Stainless Steel (CF-8M Casting) [Standard for U8]

C1A1/4" NPT Female, 316 Stainless Steel (CF-8M Casting)

A2A1/2" NPT Female, Monel

J2A1/2" NPT Female, Hastelloy C

Optional Accessories

CVCanadian Registration Number (CRN) Documentation

DSCSA Dual Seal Certified Construction

HTUniversal Stainless Steel Terminal Junction Box (1/2" NPT)

NCNACE MR0175 / ISO 15156 Sour Gas Compliance

PKPipe / Stanchion Mounting Kit for 1-1/2" to 2" Pipe

PY316 Stainless Steel Tag with 304SS Wire

YYExterior Polyimide Epoxy Coating with 316SS Pigment

SOR Model Architecture

6BL-KB3-U8-C2A-YY

6PistonPiston #6 (12 to 100 psi span)

BLHousingUL/CSA Explosion-Proof Housing

KBSwitchSPDT Hermetically Sealed 15A Switch

3SpringRange Spring #3

U8DiaphragmU8 Fire-Safe Welded Diaphragm System

C2APressure Port1/2" NPT Female 316SS

YYAccessoriesPolyimide Epoxy External Coating

Technical specifications

Adjustable Range Span30 in Hg Vac to 7,000 psi (1 bar Vac to 480 bar)

Repeatability±1% of full adjustable span

Hazardous Location RatingUL / CSA Class I, Groups A, B, C, D; Class II, Groups E, F, G; Div 1 & 2

Enclosure ProtectionNEMA 4, 4X, IP65 (Copper-Free 356 Cast Aluminum)

Switching CapsuleHermetically sealed steel capsule SPDT or DPDT

Fire-Safe RatingTested at 1,900 °F for 30 minutes under overrange pressure (US Pat. 4,438,305)

Process Connection1/2" NPT Female (316SS, Monel, Hastelloy)

Conduit Connection3/4" NPT Female with 18" wire leads

Ambient Temperature-40 °F to 167 °F (-40 °C to 75 °C)

Safety CertificationIEC 61508 SIL 2 Certified for SIS loops

WarrantySOR 3-Year Limited Manufacturer Warranty

Application & Field Safety Notes

Field set point adjustment is safely performed under live power without declassifying the hazardous area.

The U8 welded diaphragm system is mandatory for the complete switch assembly to carry full UL and CSA certification.

A sintered stainless steel breather drain plug prevents moisture accumulation inside the enclosure in humid environments.

Use the HT accessory when screw terminals inside an explosion-proof junction box are required instead of flying wire leads.

Product Overview & Explosion-Proof Architecture

The SOR Big Hermet Explosion-Proof pressure switch represents the benchmark for rugged process switching in severe and hazardous industrial environments. Combining the reliability of SOR's force-balance Static O-Ring piston mechanism with a hermetically sealed steel switching capsule and the patented U8 fire-safe welded diaphragm, this unit delivers maximum safety ratings without compromising ease of field service.

Process media acts on the welded diaphragm assembly, transferring force to the range spring and moving the piston shaft just thousandths of an inch to actuate the enclosed snap switch. Because the electrical contacts are sealed inside a heavy-gauge steel capsule with glass-to-metal electrical feedthroughs, explosive gases and corrosive vapors cannot contact the switching contacts. This permits external set point adjustments in the field under live power without opening the explosion-proof housing or requiring a hot work permit.

UL/CSA certified for Class I, Groups A, B, C, D (including acetylene and hydrogen atmospheres) and Class II dust ignition-proof

U8 fire-safe welded construction eliminates elastomer O-rings, ensuring process containment during catastrophic plant fires

Self-locking micrometer set point adjusting nut with visual reference scale enables rapid, repeatable set point verification

Sintered stainless steel breather drain facilitates internal moisture venting in humid coastal and offshore installations

High proof pressure ratings protect against severe pressure surges, hydraulic hammers, and pump starts

Adjustable Ranges & Piston/Spring Combinations

Piston 12 (12-4 / 12-45)0.5 to 6 psi (35 to 415 mbar) / 1 to 16 psi (70 to 1100 mbar) | Overrange: 200 psi | Proof: 400 psi

Piston 4 (4-2 / 4-4 / 4-45)2 to 8 psi (0.14 to 0.55 bar) / 2 to 25 psi / 4 to 75 psi (0.3 to 5 bar) | Overrange: 750 psi | Proof: 1,000 psi

Piston 6 (6-2 / 6-3 / 6-45)7 to 30 psi (0.5 to 2 bar) / 12 to 100 psi / 25 to 275 psi (1.7 to 19 bar) | Overrange: 1,500 psi | Proof: 2,500 psi

Piston 5 (5-3 / 5-5 / 5-45)25 to 240 psi (1.7 to 16 bar) / 35 to 375 psi / 45 to 550 psi (3.1 to 38 bar) | Overrange: 2,500 psi | Proof: 6,000 psi

Piston 9 (9-4 / 9-5 / 9-45)100 to 500 psi (7 to 35 bar) / 200 to 1,000 psi / 200 to 1,750 psi (14 to 120 bar) | Overrange: 2,500 psi | Proof: 6,000 psi

Piston 1 (1-45)500 to 4,000 psi (35 to 275 bar) | Overrange: 5,000 psi | Proof: 6,000 psi

Vacuum 54 & 5654-118: 30 inHg to 0 Vac | 56-216: 30 inHg Vac to 20 psi | 56-316: 30 inHg Vac to 160 psi

Switching Element Options & Electrical Ratings

KB Element (Standard SPDT)SPDT Hermetically Sealed Steel Capsule: 15A @ 125/250 VAC, 0.4A @ 125 VDC, 5A @ 30 VDC (Deadband x1.0)

EB Element (DPDT)DPDT Hermetically Sealed Steel Capsule: 5A @ 125/250 VAC, 0.5A @ 125 VDC, 5A @ 30 VDC (Deadband x3.5)

JR Element (Gold SPDT)SPDT Gold Contacts for low-power PLC/DCS inputs: 1A @ 125 VAC, 1A @ 28 VDC (Deadband x1.0)

JB Element (Gold DPDT)DPDT Gold Contacts for redundant low-power circuits: 1A @ 125 VAC, 1A @ 30 VDC (Deadband x3.5)

Wiring Leads18" (450 mm) 18 AWG color-coded wire leads exiting through 3/4" NPT(F) conduit opening

Model Number Architecture & Ordering Guide

SOR Big Hermet pressure switches use a 6-position ordering nomenclature: [1. Piston] [2. Housing] - [3. Switching Element] [4. Spring] - [5. Diaphragm] - [6. Pressure Port] - [Accessories].

Example Model: 6BL-KB3-U8-C2A-YY represents Piston 6 (12-100 psi), BL Explosion-Proof Housing, KB SPDT Hermetically Sealed Switch, Spring 3, U8 Fire-Safe Welded 316SS Diaphragm, C2A 1/2" NPT(F) 316SS Pressure Port, and YY Polyimide Epoxy Coating.

Housing DesignatorBL: UL Listed / CSA Certified Explosion-Proof for Class I Div 1/2 with U8 Diaphragm

Diaphragm DesignatorU8: Fire-Safe Welded Diaphragm System in 316SS, Monel, or Hastelloy (eliminates elastomer O-ring)

Pressure PortC2A: 1/2" NPT Female 316SS | C1A: 1/4" NPT Female 316SS | J2A: 1/2" NPT Hastelloy C | A2A: 1/2" NPT Monel

Popular AccessoriesCV (CRN), DS (Dual Seal), HT (SS Junction Box), NC (NACE MR0175), PK (Pipe Mount Kit), PY (316SS Tag), YY (Epoxy Coat)