When Is a 30N or 50N Gas Strut Sufficient? Solutions for Lightweight Flaps

A gas strut rated at 30 N or 50 N is designed for lightweight furniture flaps weighing approximately 3 kg to 5 kg with a maximum flap height of 300 mm to 400 mm.

When constructing wall units or shallow storage solutions, selecting the correct force rating for the fittings is a frequent challenge. A gas strut assists with opening the flap, holds it securely in the open position, and cushions the closing movement. If the strut is too weak, the flap drops shut. If it is too strong, the flap can barely be closed, or the hinges risk being torn from the cabinet carcass. For small, lightweight fronts, models with 30 N (Newtons) or 50 N provide the technical standard solution.

Key Purchasing Criteria for Lightweight Flaps

Choosing the right fitting depends on physical factors. The nominal force in Newtons indicates how much weight the cylinder can lift. As a rule of thumb: 10 N corresponds to a lifting capacity of roughly 1 kg. A 50 N strut can therefore support around 5 kg. However, the pure weight of the front is not the only decisive factor.

Flap Weight and Material

The weight of the front is calculated from the volume and density of the material. A standard front made from 18 mm chipboard weighs approximately 12 kg to 13 kg per square metre. An 18 mm MDF front comes in at around 14 kg to 15 kg per square metre. As a calculation example: an MDF flap measuring 600 mm wide and 300 mm high has a surface area of 0.18 m². Multiplied by 14 kg/m², this results in an unladen weight of 2.52 kg. Adding the weight of the furniture handle (approx. 0.2 kg) brings the total weight to roughly 2.7 kg.

Flap Height and the Law of the Lever

Alongside weight, the height of the flap is crucial. The principle works just like a playground seesaw: the longer the lever arm (the flap), the more force is required at the pivot point to hold the weight. A flap that weighs 3 kg and is 300 mm high requires less force than a flap that also weighs 3 kg but is 500 mm high. For flap heights exceeding 400 mm, 30 N or 50 N ratings are generally no longer sufficient, even if the front is lightweight. In these cases, fitters turn to gas struts for heavy flaps rated at 80 N, 100 N, or more.

Opening Angle

Standard gas struts are designed for opening angles of 75°, 90°, or 110°. The desired angle is not determined by the strut itself, but by the drilling pattern — namely the distance between the fixing points and the hinge axis. Manufacturers specify exact dimensions in mm in their technical data sheets, showing where the mounting brackets must be screwed to the carcass and the front to achieve the intended angle.

Overview of Types and Options

Even within the category of lightweight flap fittings, there are distinct variations that must be considered during planning.

• Standard gas struts: These cylinders support upward opening. When fully extended, they typically measure between 245 mm and 270 mm in length. The stroke (the travel distance of the piston rod) is typically 90 mm.
• Braking flap stays: These look visually similar but are engineered for flaps that open downwards (such as a drop-down bar cabinet). They brake the descent of the flap. A gas strut designed for upward-opening flaps must never be used on downward-opening drop flaps.
• Colour variations: Since the fittings are visible when the flap is open, they are chosen to match the interior carcass. Common options include gas struts in silver for technical contrast, gas struts in white for light-coloured cabinets, and gas struts in black for dark wood decors or anthracite carcasses.

Which Strut for Which Application?

The choice between 30 N and 50 N is made based on specific dimensions. As a general recommendation, always install two struts per flap (left and right) to prevent warping of the front panel and unbalanced strain on the hinges.

Choose 30 N (2x 30 N = 60 N total force) if:

• The front consists of lightweight materials, such as a narrow aluminium frame with a glass insert.
• The flap is very narrow and low in height (e.g. 400 mm x 250 mm).
• The application involves compact bathroom wall units where the front panel adds minimal self-weight.

Choose 50 N (2x 50 N = 100 N total force) if:

• The front is made from 18 mm MDF or chipboard and measures approximately 600 mm in width and 300 mm to 350 mm in height.
• A heavy solid stainless steel bar handle is fitted, which increases the levered weight at the bottom edge of the flap.
• The flap rests with a full overlay and the complete material weight must be supported.

If dimensions significantly exceed 600 mm in width or 400 mm in height, the 50 N range will no longer suffice. In such cases, stronger gas struts must be selected.

Installation Advice for Fitters

The correct operation of a gas strut relies entirely on precise installation. A deviation of just 5 mm in the drilling pattern can prevent the flap from closing completely or stop it from reaching the designated opening angle.

Required Tools:

• Tape measure or folding rule
• Bradawl or 2 mm wood drill bit for pilot holes
• Cordless screwdriver with a PZ2 bit
• Euro screws or 3.5 mm wood screws (typically included with the fittings)

Installation Steps:

1. Fit the hinges: The strut does not hold the flap to the carcass; it only moves it. Concealed cup hinges must be mounted first. For smooth closing, soft-close cabinet hinges are recommended.
2. Mount the carcass bracket: Secure the round or oval mounting plate to the inside of the cabinet. For a 90° opening angle on overlay fronts, the pilot hole is usually positioned approx. 250 mm to 260 mm from the hinge axis, with a 37 mm setback from the front edge (compatible with the System 32 standard).
3. Mount the front bracket: Screw the second bracket to the inside face of the flap. The distance from the hinge axis here is typically around 90 mm to 100 mm.
4. Click the cylinder into place: The piston rod (the thinner section) should generally point downwards when the flap is closed. This ensures continuous lubrication of the internal seals inside the cylinder housing. The strut simply clips onto the ball studs of the mounting plates.

FAQ – Frequently Asked Questions About Light Flap Stays

Can I install a single 50 N strut centrally instead of two 30 N struts? While technically possible, this is not recommended for wooden fronts. A single-sided or central load leads to panel warping over time on wider flaps. Always fit two lower-rated struts symmetrically on the outer sides.

What happens if I install an 80 N strut on a very light flap? The force of the cylinder will exceed the weight of the front. As a result, the flap will spring upwards forcefully when opened and will require considerable effort to close. Furthermore, the hinges will remain under constant tension and may pull out of the chipboard.

Are gas struts and soft-close dampers the same thing? No. A gas strut actively lifts and supports a flap using compressed gas. A dedicated furniture damper (often supplied as a silicone buffer or small piston cylinder) merely cushions the momentum of a closing door. These are categorised under door dampers.

How do I calculate the exact weight of my front? Multiply height (in m) × width (in m) × material thickness (in m) × material density (in kg/m³). Chipboard has a density of approx. 650 kg/m³, while MDF has a density of approx. 750 kg/m³. Finally, add the weight of the handle.

Why does my flap fail to close flush in the final centimetres? This is almost always due to an installation misalignment. If the carcass bracket is positioned too close to the back panel, or the front bracket is mounted too close to the hinge axis, the cylinder reaches its internal travel limit before the flap makes contact with the cabinet carcass. Adjust the mounting plates by 3 mm to 5 mm according to the manufacturer guidelines.