Floor springs (hydraulically regulated) for heavy doors
1992 Edition

Per the standard, the essential components of floor springs should be made from the following materials:

• Foundation box, main body, and half cover: Cast brass with at least 60% copper content and a minimum thickness of 2 mm, brass sheet not less than 1.25 mm thick, mild steel sheet of minimum 1.25 mm, cast iron, aluminium alloy die-castings with thickness not less than 2 mm, aluminium alloy sheets with minimum 1.25 mm thickness, and zinc-based alloy die-castings at least 2 mm thick.
• Spring tension guard and spring rod: Mild steel.
• Piston: Mild steel adhering to IS 226:1975.
• Cylinder and governing pivot: Mild steel or cast iron conforming to IS 226:1975 and IS 210:1978.
• Rollers: Mild steel or tempered carbon steel.
• Roller box and inner cover sheet: Mild steel sheet, inner cover with minimum 2 mm thickness.
• Top cover: Brass or brass sheet (minimum 1.25 mm), aluminium alloy die-casting (minimum 2 mm), or aluminium alloy sheet (minimum 2 mm).
• Piston player and spring: Gun metal or steel, spring steel per IS 4454 (Part 2).
• Hydraulic oil as per IS 3098:1983.

The floor spring's closing speed can be adjusted within the range of 3 to 20 seconds using a hydraulic control mechanism. This is typically achieved by manipulating a control valve screw that regulates the hydraulic fluid flow. Additionally, the spring tension can be fine-tuned by rotating the capstan nuts clockwise or counterclockwise to increase or decrease tension. For operation in low temperatures, changing the grade of hydraulic oil may be necessary to maintain proper performance. The opening force for a door leaf weighing up to 125 kg should not exceed 20 Newtons measured at 1 meter from the frame.

Floor springs must undergo rigorous testing including:

1. Endurance Test: The floor spring installed on a door leaf of 125 kg must complete 50,000 opening and closing cycles at a rate of 6 to 8 cycles per minute without showing any deterioration in function.

2. Double-Action Test (if applicable): For springs with double-action capability, 25,000 cycles of opening to 90 degrees clockwise and 25,000 cycles anticlockwise are required.

3. Functional Test: The door should open beyond 90 degrees and remain open until manually closed. If opened less than 90 degrees, the door must automatically swing back to the closed position.

Yes, the standard mandates that the shoe must fit onto the governing pivot with a square profile to ensure horizontal alignment parallel to the floor spring's top plate, allowing for precise final door leaf adjustment via screws. The top centre pivot must be securely mounted to enable smooth circular door movement, with the ability to adjust both horizontally and vertically, and allow removal of the door leaf when necessary. Materials for these components include cast brass with gun metal elements, mild steel, zinc or aluminium alloys, and brass or mild steel pins, all ensuring durability and correct function.

The floor springs specified by the standard are designed to support door leaves weighing up to 125 kilograms each without the need for additional door units. They must allow opening of the door with a force not exceeding 20 Newtons at a distance of 1 meter from the frame through a 90-degree arc. Durability testing requires that the floor spring withstands 50,000 operational cycles on such a door leaf without performance degradation.