Full Details

Name and Model Number Williams Compressor HP calculator
Country of Origin USA
Date of Manufacture  
Front Scales Compression ratio, horsepower, discharge pressure, suction pressure, cubic feet to be pumpted
Back Scales Tables of piston displacement for various compressors
Scale Length 7 ⅝
Type of Rule Disc
Construction Plastic
Area of Use Chemical
Comment From the advertisment:
A handy device for quick solution of problems relative to GAS COMPRESSORS, Capacity,
Horsepower, Suction, Intermediate and Discharge pressures, Compression Ratio, Efficiency, etc.
Designed primarily for use by Compressor operators in the rapid solution of practical compressor
and horsepower problems which arise in Gas Industry operation.s
Rarity RRR
Donor Collection of Wayne Harrison
Match Number 408
(Click Picture for Details)

In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen
(1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD.
• RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace.
• RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale.
• RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale.