|
1. Background
Chlorinated alkanes have been commonly used by far and proven
to be the most cost effective industrial cleaner/degreaser.
But most of the chlorinated alkanes have been banned or restricted
to use since 1990s with respect to health and environmental
considerations. NPB (n-propyl bromide) comes as a suitable
sustitute which is similar to trichloroethane in terms of
physiochemical properties and cleaning power. It has no flash
point, low ODP (ozone depletion potential) and GWP (global
warming potential). DF100A is NPB based which in many ways
approximates chlorinated alkanes, particularly regarding overall
performance and cost-effectiveness.
2.
Physiochemical Properties of NPB
NPB was regulated by DOT (US Department of Transportation)
as non-flammable liquid. It shows no flash point by TCC (Tag
closed cup) or COC (Cleveland open cup) tests. Besides it
has very narrow explosion limit, 4-7.8% in the open air, significantly
lower than other solvents save HCFC-225.
Table 1. Physiochemical properties of NPB and other cleaning
solvents
| |
NPB |
1,1,1-trichloroethane |
trichloroethylene |
HCFC-141b |
HCFC-225 |
| bp (°C) |
71 |
74 |
87 |
32 |
54 |
| Density, 25°C |
1.35 |
1.32 |
1.46 |
1.24 |
1.55 |
| Viscosity, cps,25°C |
0.49 |
0.79 |
0.54 |
0.43 |
0.59 |
| Vapor pressure, 20°C |
110.8 |
100 |
57.8 |
593 |
285 |
| Specific heat, 25°C |
0.27 |
0.25 |
0.22 |
0.26 |
0.25 |
| Latent heat, (cal/g) |
58.8 |
57.5 |
57.2 |
52.3 |
33 |
| Solubility in water, (g/100gH2O) |
0.24 |
0.07 |
0.11 |
0.18 |
0.033 |
| Solubility of water in solvent, (g/100g solvent) |
0.05 |
0.05 |
0.03 |
0.042 |
0.03 |
| Surface tension, (dyne/cm,20°C) |
25.9 |
25.6 |
26.4 |
19.3 |
16.2 |
| fp, TCC(°C) |
none |
none |
none |
none |
none |
| Explosion limits (w/w), % |
4-7.8 |
7-13 |
8-10.5 |
7.6-17.7 |
none |
Next
|
