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INSTALLATION MANUAL

How to size a hatch gas strut (F × S = G × ½ W), fitting advice, maintenance and the force, stroke and length of the Vetus GASSP25 to GASSP51 stainless steel gas struts.

DocumentVetus Gas Struts GASSP Installation Manual
FormatPDF · 8 pages · 1.0 MB
LanguageEnglish
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Vetus Gas Struts GASSP — Installation Manual

Technical Details

Type Force F Stroke S F × S Length L (closed) Length L+S (extended)
GASSP25 180 N (40.5 lbf) 74 mm (2 29/32") 13.3 Nm (9.8 ft.lbf) 180 mm (7 3/32") 254 mm (10")
GASSP30 135 N (30.3 lbf) 85 mm (3 11/32") 11.5 Nm (8.5 ft.lbf) 220 mm (8 21/32") 305 mm (12")
GASSP38 135 N (30.3 lbf) 140 mm (5 1/2") 18.9 Nm (13.9 ft.lbf) 240 mm (9 1/2") 380 mm (15")
GASSP44 180 N (40.5 lbf) 160 mm (6 5/16") 28.8 Nm (21.2 ft.lbf) 280 mm (11") 440 mm (17 5/16")
GASSP51 270 N (60.7 lbf) 205 mm (8 1/16") 55.3 Nm (70.8 ft.lbf, as printed) 305 mm (12") 510 mm (20 1/16")
  • Force tolerance during the extending stroke: −20 N to +30 N (4.5 lbf to 6.7 lbf).
  • Piston rod, cylinder and feet: stainless steel AISI 316; rod heads: plastic.
  • Temperature range: −30 °C to +80 °C (−22 F to 176 F).
  • End fittings: ø 18 mm (11/16") cylinder, ø 8 mm (5/16") rod; feet 63.5 × 18 mm (2 1/2" × 11/16"), holes ø 5 mm (13/64") at 51 mm (2") centres.

Selecting the Right Gas Strut

  • G = total hatch weight in N (≈ mass in kg × 10); W = hatch width.
  • For the usual arrangement: F × S = G × ½ W. Pick one strut with about that F × S, or two struts with about half the value each – always two of the same size.
  • Smaller F × S: the hatch never opens by itself. Larger F × S: the hatch opens by itself and must be secured.
  • Example: 11 kg hatch (G = 110 N), W = 600 mm = 0.6 m → F × S = 110 × ½ × 0.6 = 33 Nm. One GASSP44 (28.8 Nm) needs some force to open; two GASSP38 (2 × 18.9 = 37.8 Nm) need slight force to hold the hatch back.
  • Imperial: 25 lb hatch, W = 24 in = 2 ft → F × S = 25 × ½ × 2 = 25 ft.lbf. One GASSP44 (21.2 ft.lbf) or two GASSP38 (2 × 13.9 = 27.8 ft.lbf).

Fitting Advice

  • Fit in a dry, dust-free space; a corrosive atmosphere shortens the life.
  • Piston rod pointing downwards: the small oil charge lubricates the rod seal and damps the end of stroke.
  • Never fit too tightly: the rod heads must turn freely, the strut may only be loaded axially.
  • Fix the two supplied feet with suitable self-locking fasteners able to take the forces.
  • Keep welding and paint splashes off, and do not damage the piston rod – that ruins the seal.

Safety and Maintenance

  • Never open a gas strut: it holds nitrogen at very high pressure.
  • Hold the hatch until the struts reach their end position.
  • Store struts vertically, rod down. After a long idle period more force than specified may be needed at first.
  • Grease the rod heads lightly; wipe the piston rod with a clean cloth – no oil, grease or water.

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