Shand & Jurs 94250 Spring-Loaded Emergency Vent

For storage tank operators, refinery engineers, and EHS leaders managing tanks where fire-case set pressures exceed the practical range of weight-loaded vents, the Shand & Jurs 94250 is the spring-loaded emergency relief device that combines high-pressure emergency capacity with tight reseating.

Unlike conventional weight-loaded emergency vents — which become impractical above a few ounces per square inch as the required pallet weight grows unmanageable — the 94250 uses calibrated springs to deliver consistent emergency relief at set pressures from 1 to 15 PSIG, covering pressurized atmospheric tank applications that weight-loaded designs cannot serve.

Constant spring force immediately reseats the pallet after the overpressure event subsides, minimizing VOC and odor emissions during normal operation while delivering full relief capacity when needed. Available in 16″, 20″, and 24″ sizes with ANSI Class 125/150, API 650 roof manhole, and EN 1092-1 flange compatibility.

Body and cover materials span aluminum, carbon steel, and 316 stainless steel; spring and hardware options span plated steel and 316 stainless steel; NBR, FKM, and EPDM seal options match the stored product chemistry. CE marking for ordinary EU service and ATEX II 1 G Ex h IIB T1–T6 Ga for hazardous-area installations are available on lower-pressure configurations.

Features

Calibrated springs deliver consistent emergency relief at 1 to 15 PSIG set pressures, covering ranges weight-loaded vent designs cannot reach.

Constant spring force immediately reseats the pallet after an overpressure event subsides, minimizing VOC and odor emissions during normal operation.

Set pressures up to 15 PSIG enable use on pressurized tanks beyond the reach of conventional weight-loaded emergency vent designs.

Body, cover, spring, and hardware options span aluminum, carbon steel, and 316 stainless steel for diverse process chemistries.

NBR, FKM, and EPDM seal options accommodate hydrocarbons, aggressive chemicals, and elastomer-sensitive process fluids across a wide temperature range.

CE marking for ordinary EU locations and ATEX II 1 G Ex h IIB T1–T6 Ga for hazardous-area service available on specified configurations.

Applications

High-Pressure Liquid Storage: Atmospheric tanks operating at elevated working pressures where set points exceed the practical range of weight-loaded emergency vent designs.
Petroleum & Chemical Storage: Pressurized tanks storing flammable hydrocarbons or aggressive chemicals requiring high-set-point fire-case overpressure protection.
Refinery Process Tanks: Process intermediate and finished-product tanks held at pressures above the range conventional atmospheric venting can serve.
Pressurized Wastewater Digesters: Anaerobic digesters operating at elevated headspace pressures needing biogas overpressure relief at PSIG-range set points.
Tank Farms with VOC Controls: Sites where low fugitive emissions during normal operation matter and tight pallet reseating is required between relief events.
Hazardous-Area Installations: Service at facilities where ATEX II 1 G Ex h IIB T1–T6 Ga marking is required on emergency vent equipment.

Technical Specifications

Parameter

Specification

Function

Emergency overpressure relief (spring-loaded)

Pressure Setting Range

1.0 to 15.0 PSIG (15 discrete ordering ranges)

Nominal Sizes

16″, 20″, 24″

Flange Standards

ANSI Class 125 / 150 FF; ANSI 150 RF (steel & SS only); API 650 FF (20″ and 24″ only); EN 1092-1 FF

Base Material

Aluminum, Carbon Steel, or 316 Stainless Steel

Cover Material

Aluminum, Steel, or 316 Stainless Steel

Spring &Hardware

Plated Steel (standard); 316 Stainless Steel optional

Seal Material

NBR (Nitrile-Butadiene), FKM (Fluoroelastomer), or EPDM (Ethylene Propylene Diene Monomer)

Process Temperature Range

−20°F to +400°F (body and seal options selected per tank product chemistry)

Approvals

CE marking for ordinary EU service; ATEX II 1 G Ex h IIB T1–T6 Ga for hazardous-area service (limited to set pressures ≤ 7.5 PSIG / 0.5 Bar)

Quality System

Manufactured under an ISO 9001-certified quality system

Standards Alignment

Sized per API 2000 fire-case methodology; supports NFPA 30 emergency-venting programs; conformance determined at the site level

2026 COST ESTIMATE

Contact Support

If you have questions not covered here, please contact the Cognesense support team for assistance.

When should I specify the 94250 instead of the 9420X Series weight-loaded design?

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Specify the 94250 when the required set pressure exceeds the practical range of a weight-loaded pallet — typically above a few ounces per square inch. The 94250 covers 1 to 15 PSIG, where weight-loaded designs become impractical because pallet mass grows unmanageable. For lower-set-point fire-case relief, the 9420X Series weight-loaded design is the right choice.

What set pressure ranges does the 94250 cover?

Fifteen discrete ordering ranges from 1.0 PSIG up to 15.0 PSIG, in 1-PSIG increments. CE and ATEX certified configurations are limited to set pressures at or below 7.5 PSIG (0.5 Bar) per the certification scope.

What materials are available for body, cover, and seal?

Base and cover options are aluminum, carbon steel, or 316 stainless steel. Spring and hardware are plated steel by default with stainless steel optional. Seal material is selected from NBR, FKM, or EPDM based on the stored product chemistry. Specify the tank product when ordering to ensure correct seal selection.

Is the 94250 available for hazardous-area installations?

Yes. CE marking for ordinary EU locations and ATEX II 1 G Ex h IIB T1–T6 Ga marking for hazardous-area service are available, both limited to set pressures ≤ 7.5 PSIG (0.5 Bar). For higher-pressure service, non-certified configurations are available.

How does the 94250 reseat after a relief event?

The calibrated springs deliver constant downward force on the pallet across the relief cycle. When tank pressure drops below the set point, the springs immediately return the pallet to the seat, restoring vapor containment and minimizing VOC and odor emissions between events.

What flange standards are supported?

ANSI Class 125 / 150 flat-face is standard. ANSI Class 150 raised-face is available on steel and stainless steel bodies. API 650 roof-manhole flange drilling is available on 20″ and 24″ sizes. EN 1092-1 flat-face is available for European installations. Custom drilling can be specified.

Does the 94250 also serve as a tank manway?

The 94250 is configured primarily as a spring-loaded emergency vent rather than a combined vent-and-manway. For combined fire-case emergency relief with personnel access on the same tank opening, see the 9420X Series weight-loaded emergency vent and manhole cover or the 94225 Series pressure-and-vacuum design.

How is the 94250 sized for fire-case overpressure relief?

Sizing follows the API 2000 methodology for fire-case vapor generation rates and tank wetted-surface area. Shand & Jurs WinSize (EZ-Flow) software supports the calculation. Final selection must account for tank design pressure, contents volatility, and any other concurrent venting paths; site-level conformance is the operator’s determination.

How does the 94250 compare to a pressure relief valve (PRV)?

A PRV is sized for a specific defined relief scenario at a defined set pressure, often used on pressure vessels rated to ASME Section VIII. The 94250 is an emergency relief device for atmospheric tanks designed to discharge large vapor volumes during fire-case events with a tight reseating spring-loaded pallet — a different category from a PRV and not interchangeable with one.

94250 Spring-Loaded Emergency Vent