Bulletin Volume 4, Nos. 1-3 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...The variation in steam pressure is very great; we find plants in different localities operating with pressures as low as 80 pounds and as high as 200 pounds per square inch. Other things being equal, the higher the steam pressure, the greater the economy. In connection with the subject of type of prime movers, one of the most reputable concerns in the market for feed-water heaters has said that it does not make so much difference what type of prime mover is selected as it does what type of feed-water heater. While this statement ought to be taken with a grain of salt, yet upon analysis of same with a view of the relative qualities of heat extracted from the working fluid by the two while performing their respective work with best economy, it will be seen that there is much truth in the statement. Specifications. It is necessary in securing machinery for a plant to write general and sometimes detailed specifications. It is best practice to make specifications as general as possible. For the prime movers and auxilliaries, they can, perhaps, be so general as to state only type, capacity and speed and a concise statement of conditions under which they are to operate, leaving all details to the bidders. This allows each one in the market for such work to quote upon their standard sizes and such quotations will in all probability be the lowest to meet the requirements. A policy like this assumes, and rightly, too, in the majority of cases, that the manufacturers know best the various working peculiarities and conditions the machines have to meet and can supply a more suitable and perhaps cheaper unit than if the purchaser specifies minute details. The purchaser or engineer representing some have a wide field to select from when all bids come under his scrutiny. H...