Shell BP stack-loss slide rule

Rule 1 Based on an oil with C.V. of 18500 B.t.u./lb - 10260 Kgcal/Kg. Gross 17700 B.t.u./LB - 9860 Kgcal/Kg. Net	Rule 2 Based on an oil with C.V. of:- 20,000 B. t. u./LB - 11,111 Kg Cal/Kgm. Gross 18,700 B. t. u./LB - 10,389 Kg Cal/Kgm. Net

full-size images: 111 kB (above) and 52 kb (below)	full-size images: 107 kb (above) and 62 kb (above)

For how to use this slide rule see Ron Manley's web site here.	Transcription of the instruction leaflet that accompanied the above rule.
	COMBUSTION EFFICIENCY SLIDE RULE SCALES Face: Gross stack loss % (red) CO2 % in flue gases (black) Temperature of flue gases, nett deg F (red) Temperature °C (green) C D for general calculations (black) Nett stack loss % (green) Reverse side of slide: Excess air % (red) CO2 % (black) O2 % (green) TO DETERMINE STACK LOSS Set the hairline on the cursor against CO2 % reading, move the slide until the nett stack temperature in deg F (gross stack temperature minus temperature of air entering the burner) coincides with the cursor hairline and the CO2 reading set. Then move the cursor until the hairline registers with the engraved arrows (red and green) on the slide and read off the stack loss, gross or nett on the top or bottom scale. The combustion efficiency can then be assessed from the stack loss. TEMPERATURE CONVERSION Using the cursor, read directly across between the red and green temperature scales on the slide. NOTE: These scales should only be used for converting spot temperatures and not nett stack temperatures. GENERAL CALCULATIONS Use the logarithmic C and D scales. DETERMINATIONS OF EXCESS AIR % AND OXYGEN % IN THE FLUE GASES Reverse the rule and set % CO2 on the hairline - read off % excess air and % oxygen direct. J. D. MACLEAN & CO. LTD. Slide Rules, Mathematical Instruments etc. LONDON W.C.2

This page was last updated on 14 December 2002.