Relative Density
A relative density of 1 is equivalent to a density of 1g per cm
The following table shows the relative density of water and steel compared to materials commonly used in the manufacture of fibe ropes.
| Relative Density |
| Material |
Relative Density
|
| Nylon |
1.14 |
| Polyester |
1.38 |
| Polypropylene |
0.91 |
| HMPE |
0.97 |
| Aramid |
1.44 |
| Vectran |
1.41 |
| Zylon |
1.54 |
| Fresh Water |
1 |
| Sea Water |
1.03 |
| Steel |
7.85 |
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| Derived S1 Units |
| Quantity |
Name |
Unit Symbol |
Expressed
As Basic
SL Units |
Expressed
As Basic
SL Units |
| Force |
newton |
N |
kg m s¯²
|
N/m² |
| Pressure Stress |
pascal |
PA |
kg s¯²m ˉ¹ |
Nm |
| Energy Work |
joule |
J |
m¯²kg s‾²
|
|
| Power |
watt |
W |
m²kg s ־³
|
J/s |
| Electrical Charge |
coulomb |
C |
A S |
|
| Electrical Potential |
volt |
V |
m²kg s ־³A ˉ¹
|
J/C |
| Electrical Capacitance |
farad |
F |
F |
CV |
| Frequency |
hertz |
Hz |
sˉ¹
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Characteristics of Fibres |
| Comparative Charactersistics of various Fibres |
|
Nylon
|
Polye-ster |
Poly-rene |
PP/Poly-steel |
Polyth-ylene |
Cotton |
| Strength: |
| Tenacity of dry fibre (in grams/denier) |
9.0 |
8.5 |
7.5 |
7.2 |
5 - 6.0 |
2 - 3.0 |
| Wet strength compared to dry strength |
85 -90% |
100% |
100% |
100% |
100% |
Up to 120% |
| Rope shock load absortion abilit |
Excellent |
Good |
Very Good |
Very Good |
Very Good |
Very Poor |
|
| Weight |
| Specific gravity of fibres or filaments |
1.14 |
1.38 |
1.14 |
0.91 |
0.95 |
1.54 |
| Able to float |
No |
No |
No |
Yes |
Yes |
No |
| Rope Strength/wgt.ratio (average) |
3,0 |
2,25 |
2,5 |
2,5 |
2,1 |
0,50 |
|
| Elongation |
| Typical per cent of rope elongation @ Break |
20-30% |
12-18% |
12-18% |
18-22% |
20-25% |
10% |
| Creep (extention under sustained load) |
Moderate |
Low |
Low |
High |
High |
Low |
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Unreeling New Rope Remove rope properly from reels to prevent kinking. The rope should be removed by pulling it off the top while the reel is free to rotate. To proceed in any other manner may cause kinks or strand distortion. Never unreel rope from the side of the drum.
Handling Never stand in line with rope under tension. If a rope fails it can recoil with lethal force. Synthetic rope has higher recoil tendencies than natural fibre rope. Reverse rope ends regularly. This permits even wearing and assures a longer, useful life.
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