Why the pressure inside a gas strut is not the same thing as the force your lid, hatch, cover or access panel actually feels.
Gas strut pressure is not one fixed PSI value; it is set by the force target, rod area, internal gas volume, stroke position and temperature. A buyer should normally specify gas strut pressure as a required force rating, such as 300 N (67 lbf), rather than asking for a generic PSI number.
That distinction matters on real equipment. A service door may need to lift smoothly, stay open without drifting, and close without bending a hinge. The pressure inside the cylinder helps create that behavior, but the installed result depends on the rod diameter, gas charge, mounting geometry, temperature and whether the design uses one spring or a matched pair.
This guide is written for OEM engineers, procurement teams and aftermarket distributors who see PSI, bar, N and lbf used in the same conversation and want a clean way to specify the correct part.
- 1 How gas strut pressure becomes force
- 2 Why gas strut pressure is not the right purchasing spec
- 3 The common mistake: asking for more PSI when the geometry is wrong
- 4 F1, stroke position and why the force is not perfectly constant
- 5 Stop specifying PSI: specify the force curve the application actually sees
- 6 Temperature changes pressure before anything has leaked
- 7 Mounting details that change the result more than PSI
- 8 Material and seal choices for pressure stability
- 9 Newtone specification quick reference
- 10 Why source pressure-rated gas springs from Newtone
- 11 Related Newtone products
- 12 Gas strut pressure FAQ
- 13 The useful answer is force, not just pressure
How gas strut pressure becomes force
Gas strut pressure becomes useful push force when the internal pressure differential acts on the rod cross-sectional area. The simple relationship is:
F = ΔP × A
Where F is force, ΔP is the pressure differential across the rod, and A is the rod cross-sectional area.
A = π × d² ÷ 4
Where d is rod diameter.
Worked example: take an 8 mm (0.31 in) rod. Its area is π × 8² ÷ 4 = 50.3 mm² (0.078 in²). If the effective pressure is 80 bar (1160 psi), the theoretical force is 8 N/mm² × 50.3 mm² = 402 N (90 lbf). In inch units, 1160 psi × 0.078 in² gives the same 90 lbf (402 N) result.
That is the clean physics. The delivered force can be lower after seal friction and internal losses, and the force will rise slightly as the rod is pushed into the cylinder because the available gas volume gets smaller.
This is why rod diameter is not a cosmetic catalogue dimension. A larger rod area gives more force at the same internal pressure. It is also why two gas springs with the same PSI are not automatically interchangeable if the rod size, stroke, tube volume or construction is different.
Why gas strut pressure is not the right purchasing spec
Gas strut pressure is mainly a manufacturing charge variable; the useful purchasing spec is the force rating in N (lbf) at a defined condition. In normal replacement and OEM sourcing, the number printed on the body is the force rating, not the internal pressure.
For example, a 250 N (56 lbf) gas spring and a 600 N (135 lbf) gas spring may both be built from similar-looking cylinders. The difference is not only “more PSI.” It may include a different rod diameter, gas charge, internal volume, stroke, seal package and force progression. If you ask for PSI alone, the supplier still has to reverse-engineer the actual job the spring must do.
A better request is practical: “The hatch is 18 kg (40 lb), the hinge-to-center-of-gravity distance is 420 mm (16.5 in), we use two springs, the open angle is 70 degrees, the closed length available is 285 mm (11.2 in), and the equipment works down to −20°C (−4°F).” With that information, the pressure can be charged to produce the correct force rather than guessed.
The common mistake: asking for more PSI when the geometry is wrong
If a panel drops, slams or refuses to stay open, the fix is not always higher pressure. The spring may be mounted with a poor moment arm, installed off-plane, paired with a mismatched second spring, or sized at room temperature for a colder field environment.
Adding force can hide the symptom and create a new failure. A spring that is too strong can overload hinges, make closing uncomfortable, keep seals under high static load, or twist a wide door when only one side is doing the work. Get this wrong and the hinge pays for it.
F1, stroke position and why the force is not perfectly constant
The force rating on a gas strut is a reference value, not a promise that the same force exists at every millimeter of stroke. Gas springs are often described by F1, the extension force measured near full extension under defined conditions, commonly around 20°C (68°F).
As the rod enters the cylinder, it displaces gas volume. Smaller volume means higher pressure, so the spring force rises toward the compressed position. This is called force progression or K-factor. A typical gas spring does not behave like a perfect constant-force device; it behaves like a sealed gas volume with a controlled, relatively low force rise across the stroke.
For the buyer, this explains a lot of field confusion. A gas strut that measures 400 N (90 lbf) near extension may feel firmer near the closed position. A hatch that is easy to start moving may still need a careful closing force check near the last part of travel. That is not a defect by itself. It is part of the pressure-volume behavior.
Stop specifying PSI: specify the force curve the application actually sees
The strongest RFQ is not “give me a 900 psi gas strut”; it is a short description of the movement, load and environment. Pressure belongs inside the manufacturing process. Application behavior belongs in the specification.
| Send this information | Why it matters |
|---|---|
| Required force in N (lbf), if known | Sets the target output force instead of guessing from PSI. |
| Panel weight in kg (lb) | Defines the load that must be assisted or held. |
| Hinge and pivot geometry in mm (in) | Changes the moment arm more than many force changes do. |
| Stroke, extended length and compressed length in mm (in) | Confirms that the spring can fit closed and reach the open position without bottoming. |
| End fittings and brackets | Controls alignment, articulation and side-load risk. |
| Temperature and environment | Pressure changes with temperature, and corrosion risk changes material choice. |
| Single or paired springs | Paired springs should be force-matched, typically within ±5% and from the same production batch. |
For a wide cover, two lower-force matched springs are often better than one stronger spring. They split the load, reduce twisting and give a more balanced feel. For prototypes, adjustable force can be useful, but production programs should settle on a stable force value once the geometry is proven.
Temperature changes pressure before anything has leaked
A cold gas strut can feel weak because gas pressure changes with temperature, not necessarily because the spring has lost gas. A practical estimate is:
FT ≈ F20 × [1 + 0.003 × (T − 20°C)]
Example: a 500 N (112 lbf) spring rated at 20°C (68°F) used at −20°C (−4°F) changes by 0.003 × (−40) = −0.12. Estimated cold force is 500 N × 0.88 = 440 N (99 lbf).
That 60 N (13 lbf) difference is large enough for a technician to feel on a hatch or service door. Newtone gas springs are specified for −40°C to +100°C (−40°F to +212°F), but the force at the operating temperature still has to be considered during sizing.
A representative case we see in winter-service equipment starts with a simple complaint: “The struts lost pressure.” After reviewing the temperature and door geometry, the correction is often not to add raw force blindly. The better fix is to size the 20°C (68°F) rating so the panel still behaves properly at the cold operating point, without becoming overpowered when the equipment returns to a warm workshop.
Mounting details that change the result more than PSI
Installation geometry can make the same gas spring feel correct, weak or aggressive. The pressure inside the cylinder has not changed, but the mechanical advantage has.
Keep the load axial
Gas springs are designed for axial load. Keep both pivots in the same plane of motion and use suitable ball sockets, eyelets or brackets so the rod is not side-loaded through the stroke.
Mount rod-down where practical
The normal best practice is to mount the rod pointing down in the at-rest or closed position. This helps keep oil near the seal and supports smoother damping and seal lubrication.
Do not use the gas spring as a hard stop
The stroke and brackets should allow the spring to reach the open position without bottoming or carrying impact load as the mechanical stop.
Move the pivot before blaming pressure
A few millimeters of pivot change can alter the effective moment arm. On a hinged cover, that may change the opening feel more than a small pressure increase.
Material and seal choices for pressure stability
Pressure stability depends on the charge, but long service life depends heavily on rod finish, seals and environment. For standard industrial and vehicle applications, Newtone’s black nitrided rod surface and HNBR sealing are normally the correct baseline.
Newtone rods use black nitriding at 900–1000 HV with a 20–30 µm (0.020–0.030 mm / 0.0008–0.0012 in) treated layer, and HNBR seals are selected for UV and ozone resistance. For coastal, marine, washdown or high-humidity equipment, stainless steel gas springs are the better route. For service covers that must hold safely during maintenance, locking gas springs may be more appropriate than simply raising force.
The job is to choose a construction that keeps the rated force useful over time. Low-grade seals, side load, rod pitting and over-force specs are more likely to create trouble than a small difference in catalogue pressure language.
Newtone specification quick reference
For most general gas strut pressure replacement work, the typical catalogue force band sits around 50–1300 N (11–292 lbf), while Newtone’s production capability covers 20–7500 N (4–1686 lbf). OEM and aftermarket supply can be built from the same platform, which helps distributors replace an original behavior instead of only matching a similar-looking cylinder.
Why source pressure-rated gas springs from Newtone
Manufacturer, not distributor
Newtone manufactures gas springs in Turkey and exports to 60+ countries, giving OEMs and distributors direct access to force, stroke and end-fitting configuration.
Engineering-led RFQ review
Instead of treating PSI as the part number, Newtone reviews the load, geometry, environment and target behavior before recommending a force.
Matched pairs available
For double-spring installations, force matching within ±5% and same-batch supply help reduce uneven lift and one-sided hinge wear.
Fast technical response
Newtone responds within 5 business hours, so buyers can move from incomplete pressure questions to a usable specification quickly.
Related Newtone products
For standard lift and counterbalance applications, start with standard gas springs. If the project needs special material protection, review stainless steel gas springs. If the panel must remain locked open during service, consider locking gas springs. Correct mounting brackets are just as important as force, because poor alignment can shorten service life.
Gas strut pressure FAQ
There is no single gas strut pressure value. Internal pressure is set by the required force, rod diameter, stroke volume, temperature and product series, so two gas struts with the same PSI can produce different force ratings.
No. For buying or replacing a gas strut, specify the force rating in N (lbf), stroke, extended length, compressed length, end fittings and mounting geometry. PSI is mainly a manufacturing charge parameter.
Use F = ΔP × A, where F is force, ΔP is pressure differential and A is rod cross-sectional area. For example, 80 bar (1160 psi) acting on an 8 mm (0.31 in) rod area produces about 402 N (90 lbf) before friction and seal load.
Gas pressure changes with temperature, so force changes by about 0.3% per °C. A gas strut rated at 20°C (68°F) can feel noticeably weaker at −20°C (−4°F), even if it has not leaked.
Send the required force if known, panel weight, pivot geometry, stroke, extended and compressed lengths, end fittings, operating temperature, environment and whether one or two gas springs are used. Newtone can then match the correct force and construction.
The useful answer is force, not just pressure
Gas strut pressure explains how the spring creates force, but it should not be treated as the full specification. The correct part is chosen by force rating, geometry, stroke, temperature, fittings, material and service behavior. PSI is only one internal piece of that engineering picture.
Send Newtone the application details and the team can help turn a pressure question into a force-controlled, production-ready gas spring specification.
