Fire or smoke barrier

1. A smoke or fire barrier having a curtain comprising:

a head box for housing the curtain, open at its underside to allow the curtain to be deployed and withdrawn;

a roller, housed in the head box, for the curtain to be rolled from for deployment and rolled back onto for withdrawal; and

a bottom bar attached to a bottom of the curtain for weighing down the curtain when deployed, wherein the bottom bar closes the open underside of the head box when the curtain is withdrawn;

the head box having:

two air duct end fittings for passing clean air;

two apertures for clean filtered air circulation, one of the two aperture for admission of clean air to the head box and the other aperture of the two apertures for withdrawal of the air from the head box,

wherein each said aperture is provided on a topside of the head box with a spring loaded trap also fitting to the topside of the head box,

wherein each said spring loaded trap is normally held open by a fusible link, the link fusing in event of fire; and

wherein each said spring loaded trap and each said aperture are provided within each said air duct end fitting.

2. A smoke or fire barrier as claimed in claim 1 , including a supply of clean air to be circulated through the head box to keep the head box clean.

3. A smoke or fire barrier as claimed in claim 1 , wherein air ducts route the air to and from the two apertures.

4. A smoke or fire barrier as claimed in claim 3 , wherein the air ducts are connected to a clean air circulation via a filter.

5. A smoke or fire barrier as claimed in claim 1 , wherein the fusible link will be such as to rupture between 57-150° C.

6. A smoke or fire barrier as claimed in claim 1 , wherein each said spring loaded trap has a fixed guide, typically formed as a sheet metal pressing, for a moveable trap member, with at least one spring acting between the guide and the trap member.

7. A smoke or fire barrier as claimed in claim 1 , wherein each said spring loaded trap will include at least two springs.

8. A smoke or fire barrier as claimed in claim 6 , wherein the guide has an upstand at one end with each said spring loaded trap having a complementary upstand and a plurality of springs acting between them.

9. A smoke or fire barrier as claimed in claim 6 , wherein the guide has:

an abutment for regulating the closed position in each said spring loaded trap; and/or

an aperture complementary to the aperture on the head box; and/or

C-shaped channels along edges of the guide to guide each said spring loaded trap over the two apertures.

10. A smoke or fire barrier as claimed in claim 6 , wherein the fusible link can be attached to the fixed guide and movable trap member.

11. A smoke or fire barrier as claimed in claim 6 , wherein the fusible link can be formed of two portions attached by a fusible material, one of the two portions being attached to the guide and the other portion attached to the trap member to allow closure of the trap member on a rise in temperature,

the two portions of the fusible link are normally held together, but on sufficient temperature rise, the material will melt, releasing the two portions of the fusible link and allowing the trap member to close the two apertures in the head box.

12. A smoke or fire barrier as claimed in claim 11 , wherein the two portions can be held together by a material having a low melting point range typically between 57-150° C.