248 mm plastic slide rule for chemical engineers
(Click on the small pictures to see full-size images.)
 |
| (full-size
image: 240 kB) The front of this slide rule has a conventional set of scales: LnI-1 LnI0 LnI1 A1 [Lg1-1 T S CI C] D Ln1 Ln0 Ln-1 The model number is on the slide but is hidden in the picture by the right-hand of the two brackets holding the two halves of the stock together. |
 |
| (full-size
image: 223 kB) This side has two log-log scales and the special scales for chemical engineering. Most of these scales are identical to those on the Hemmi 257 and 257L rules. |
| Scales | Purpose of Scale | |
LnI-2 |
log-log scale | |
| Ch | two scales for setting atomic (and a few molecular) weights | |
| Mz | Xz | density unit conversion |
| M | X | density unit conversion |
| °F | Fahrenheit temperature scale | |
| °C | Celsius temperature scale | |
| F(t) | Two
scales for the calculation of the adiabatic compression
and expansion of a gas: left-hand scale for air and right-hand scale for CO2. |
|
Kg/cm2 |
pressure scale | |
mmHg |
atm |
pressure scale |
tw |
vapour pressure of water | |
| Ln-2 | log-log scale | |
The C scale can be used as a °K scale and has the following gauge marks.
| R1 | 1.986 | cal deg-1 mole-1 | molecular gas constant |
| R2 | 62.36 | litre mmHg deg-1 mole-1 | molecular gas constant |
| R3 | 0.08205 | litre atm deg-1 mole-1 | molecular gas constant |
| V0 | 22.414 | litre mole-1 | standard molecular volume of an ideal gas |
| F | 26.8 | amp hr g-equiv-1 | Faraday constant |
| K | 0.3594 | °K mmHg-1 | volume correction factor of an ideal gas |
| J | 4.185 | joule cal-1 | work equivalent of heat |
The complete instruction manual for the Hemmi 257 slide rule can be found on the Sphere Research Slide Rule Site by clicking here.
This page was last updated on 8 June 2000.