Shand & Jurs 94116 Snap Action Vacuum Breaker

For petroleum terminal engineers, tank designers, and storage specifiers, the Shand & Jurs 94116 addresses vacuum protection in atmospheric storage tanks where rapid pressure drops can exceed the response capability of conventional weight-loaded vents.

Unlike weight-loaded vacuum vents that lift progressively and can allow transient vacuum overshoot during rapid pump-out, the 94116 opens instantly at the specified setpoint via a magnetic-latch snap-action mechanism, achieving full lift without additional over-vacuum.

Vacuum settings are available as low as 0.4 in. W.C., allowing high-capacity air admission at minimal differential pressure. The body is rated for static pressure up to 1.5 PSIG, supporting installations where moderate positive pressure may exist between cycles. A vertical-hinged pallet and self-draining body reduce condensate accumulation at the seat interface.

Designed using API 2000 sizing methodology and supported by Shand & Jurs WinSize (EZ-Flow), the 94116 is supplied in 16″–42″ sizes with ANSI, API 650, or API 605 flat-face flange drilling for atmospheric storage applications.

Features

Maintains tight closure below setpoint and delivers instant full opening at calibrated vacuum, eliminating gradual preload behavior common to weight-loaded vacuum vents.

Achieves 100% opening immediately at the calibrated vacuum threshold, providing full airflow capacity without additional over-vacuum during rapid inbreathing events.

Vacuum settings from 0.4–1.5 in. W.C. support tanks with narrow allowable vacuum design margins, enabling high-capacity airflow at minimal differential pressure.

Vent body tolerates moderate positive pressure between vacuum cycles, supporting installations where tank static pressure may exceed strict atmospheric conditions.

Hinged pallet configuration promotes stable lift and repeatable reseating during cyclic operation, maintaining consistent sealing behavior across repeated transient events.

Body geometry directs condensate away from the seat interface, reducing seat fouling and preserving sealing integrity in wet-vapor and cold-weather service conditions.

Applications

Rapid Pump-Out Systems: Delivers instantaneous full-lift vacuum relief during rapid liquid withdrawal where conventional weight-loaded vents allow transient vacuum overshoot that threatens tank integrity.
Thermal Contraction Events: Admits high-volume airflow during rapid cooling and thermal contraction, preventing structural damage on atmospheric tanks exposed to sudden ambient temperature drops.
Atmospheric Storage Tanks: Protects atmospheric tanks with narrow allowable vacuum design margins where setpoint overshoot or delayed response would exceed structural tolerance limits.
Rupture Disc Replacement: Provides a reusable snap-action alternative to single-use rupture discs on large-diameter vacuum relief applications, eliminating disposable-element replacement cycles.
Petroleum Terminals: Suits petroleum terminal storage exposed to rapid pump-out and aggressive thermal cycling where snap-action response outperforms conventional weight-loaded vacuum vents.
High Airflow Demand Systems: Large 16" to 42" body sizes deliver vacuum airflow capacity required by large-diameter atmospheric tanks during sustained withdrawal or bulk transfer operations.

Specifications

Parameter

Specification

Device Type

Snap-action vacuum breaker

Vacuum Setting Range

0.4–1.5 in. W.C.

Static Pressure Rating (MAWP)

1.5 PSIG

Sealing Method

Magnetic-latch pallet assembly

Loading Method

Permanent magnet snap-action mechanism

Nominal Sizes

16″, 20″, 24″, 30″, 36″, 42″

Connection Types

FF ANSI; FF API 650; FF API 605

Body and Seat

Aluminum or 316 Stainless Steel

Pallet

Aluminum or 316 Stainless Steel (316 SS pallet not available for lowest vacuum settings)

Diaphragm

NBR

Screen

Galvanized Steel or 316 Stainless Steel

Weights

Lead counterweight

Hardware

Stainless Steel

Sizing Basis

API 2000 (Shand & Jurs WinSize / EZ-Flow)

Options

316 Stainless Steel body and internals; API 650 or API 605 flange drilling; Teflon-coated stainless seat and pallet; low-range vacuum calibration (0.4–0.6 in. W.C.); explosion-proof open-position limit switch; left or right access panel orientation

2026 COST ESTIMATE

Contact Support

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

How does the snap-action mechanism differ from a weight-loaded vacuum vent?

−

Weight-loaded vacuum vents lift progressively as vacuum approaches the setpoint, often allowing transient vacuum overshoot before the pallet opens fully. The 94116 uses a magnetic-latch mechanism that holds the pallet closed until the exact setpoint, then releases for instant 100% opening. This limits peak vacuum duration and reduces transient structural loading during rapid pressure-drop events.

What vacuum settings are available?

Standard vacuum setting range is 0.4 to 1.5 in. W.C. A low-range calibration option extends from 0.4 to 0.6 in. W.C. for tanks with extremely narrow allowable vacuum limits. Note: 316 stainless pallet is not available for the lowest vacuum settings per the original specification.

What is the static pressure rating?

The vent body is rated for a maximum allowable working pressure (MAWP) of 1.5 PSIG static pressure between vacuum cycles. This supports atmospheric tanks that may experience moderate positive pressure without compromising snap-action operation.

What sizes and flange drilling patterns are offered?

The 94116 is available in 16″, 20″, 24″, 30″, 36″, and 42″ sizes. Flat-face flange drilling includes ANSI, API 650, and API 605 patterns, matching common tank nozzle bolt circles on petroleum storage vessels.

Is an explosion-proof position indicator available?

Yes. An explosion-proof open-position limit switch is offered as an option. This provides remote indication when the pallet reaches the fully open position, supporting monitoring on regulated and hazardous-area installations.

How is relief capacity sized?

Capacity is sized using API 2000 methodology supported by Shand & Jurs WinSize (EZ-Flow), based on anticipated vacuum demand and allowable pressure drops. WinSize sizing supports defensible vent selection aligned with the site code-of-construction.

Can the body be supplied in stainless steel?

Yes. 316 stainless steel body and internals are available for aggressive vapor or wastewater environments where aluminum corrodes. Teflon-coated stainless seat and pallet are also offered for sticky or fouling service conditions.

Summary

With over a century of tank-safety heritage inside Cognesense, the Shand & Jurs 94116 Snap Action Vacuum Breaker is chosen when atmospheric tanks require full-lift vacuum relief at the exact setpoint without overshoot. A magnetic-latch snap-action mechanism, low-range vacuum settings, 1.5 PSIG static pressure capability, and 16″–42″ body sizes deliver predictable high-volume airflow and spec-ready protection on rapid pump-out and thermal contraction service. For snap-action vacuum protection, it is trusted wherever you need to measure, monitor, and protect what matters most.

94116 Snap Action Vacuum Breaker