Jacoby Tarbox FM Dual Sight Windows — Hazardous Area Vessels — Northeast Controls Inc.

NORTHEAST CONTROLS INC.Serving Industry Worldwide Since 1937

Jacoby Tarbox — Sight Windows

FM Dual Sight Windows

FM Approved · Dual Window · Class I Div 1 & 2 · Redundant Containment · Hazardous Areas

Jacoby Tarbox FM-approved dual sight window for hazardous area vessels

FM-Approved Dual Sight Windows

FM-approved dual sight windows for classified hazardous locations. Redundant containment — if the inner window fails, the outer window maintains the pressure boundary. Prevents process fluid from reaching the hazardous atmosphere. Required for Class I Division 1 & 2 installations.

FM-approved dual sight windows are required in classified hazardous locations where flammable vapors, gases, or combustible dusts may be present. The dual window design provides redundant containment — if the inner window fails, the outer window maintains the pressure boundary and prevents process fluid from reaching the hazardous atmosphere.

Available Models

FM Dual Sight Window — Weld-PadFM Approved

FM-approved dual sight window with weld-pad mounting for vessels and pipelines in hazardous locations. The dual window design provides two independent glass windows — if the inner window fails, the outer window maintains containment. FM approval certifies the assembly for use in classified hazardous areas where flammable vapors or gases may be present.

Mounting

Weld-pad

Sizes

3/4" – 3" nominal

Pressure

Per FM approval and size

Temperature

Up to 450°F (borosilicate)

Body

Carbon Steel standard; 316 SS available

Glass

Dual borosilicate glass windows

FM Dual Sight Window — FlangedFM Approved

FM-approved dual sight window with ANSI flanged connections for hazardous area vessel and pipeline installations. The flanged design allows removal and replacement without welding. Both windows are independently sealed, providing redundant containment in the event of inner window failure.

Mounting

ANSI flanged (150# standard)

Sizes

1" – 4" nominal

Pressure

285 PSI @ 100°F (ANSI 150# P-T curve)

Temperature

Up to 450°F (borosilicate)

Body

Carbon Steel standard; 316 SS available

Glass

Dual borosilicate glass windows

How the Dual Window System Works

1.Inner window contacts the process fluid and provides primary containment

2.Outer window provides secondary containment if inner window fails

3.Space between windows is vented to atmosphere — any inner window leakage is visible

4.Outer window remains intact even if inner window fails, preventing process fluid release

5.Both windows are independently replaceable without removing the body from the vessel

6.FM approval certifies the dual-window assembly for classified hazardous locations

FM Approval Details

Approval Body	FM Global (Factory Mutual)
Classification	Class I, Division 1 & Division 2
Enclosure	NEMA 4 (weatherproof)
Documentation	FM certificate available upon request
Mounting Types	Weld-pad and ANSI flanged
Glass	Dual borosilicate glass windows

Typical Applications

→Petroleum refinery vessels

→Chemical plant reactors and tanks

→Offshore platform vessels

→Petrochemical storage tanks

→Flammable liquid storage

→Hazardous chemical process vessels

→Explosive atmosphere environments

→Classified area pipeline inspection ports

FM dual sight window sales & hazardous area compliance

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