What text must be displayed by the indicating bolt?

The mechanism must clearly display 'VACANT' when unlocked and 'ENGAGED' when locked.

What materials are acceptable for these bolts according to the code?

Typical acceptable materials include brass, aluminum alloys, and mild steel, provided they have appropriate anti-corrosive finishes.

Are there specific dimensional tolerances?

Yes, the standard specifies dimensions for the base plate, bolt slide, and indicator dial, typically found in Table 1 of the code.

IS 4621

: 1975

Specification for indicating bolts for use in public baths and lavatories

CurrentSpecializedSpecificationArchitectural · Builder Hardware

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This standard lays down the requirements regarding materials, dimensions, manufacture, and finish for indicating bolts (showing 'VACANT' or 'ENGAGED') meant for use on the doors of public baths and lavatories.

Specification for indicating bolts for use in public baths and lavatories

Quick Reference Values

indicating text optionsVACANT and ENGAGED

base plate thickness steelMin 1.25 mm

base plate thickness non ferrousMin 1.6 mm

Practical Notes

Ensure the hardware finish specified is highly resistant to moisture, as public baths and lavatories are damp, corrosive environments.

Verify the door thickness prior to installation to ensure the spindle of the indicating mechanism can engage fully without binding.

Avoid mixing incompatible metals (e.g., steel screws on aluminum plates) in damp environments to prevent galvanic corrosion.