The Mine Foreman's Handbook of Practical and Theoretical Information; Questions and Answers on Practical and Theoretical Mining, Designed to Assist Students and Others in Passing Examinations for Mine Foremanships

The Mine Foreman's Handbook of Practical and Theoretical Information; Questions and Answers on Practical and Theoretical Mining, Designed to Assist Students and Others in Passing Examinations for Mine Foremanships

By (author) 

List price: US$22.40

Currently unavailable

Add to wishlist

AbeBooks may have this title (opens in new window).

Try AbeBooks

Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1887 edition. Excerpt: ...on top and the water from the condensed steam falling down the shaft has a very injurious efiect on the upcast current. lf the jet is arranged to blow down, this objection is overcome, but in winter the cold air coming directly in contact with the steam condenses it and greatly reduces the efiect. The best result isobtained by the steam issuing from an annular orifice, thus increasing the surface in contact with the air. The jet should be inserted in the bottom of an expanding chimney like the discharge of a fan. By this arrangement the speed of air in passing through the contracted opening is brought much nearer the velocity of the steam, and the loss of steam momentum is less in overcoming the inertia of the air. Then the current being slowed in the expanding chimney has the same effectas with the fan, the velocity being changed to pressure at the pointof expulsion into the surrounding atmosphere. 'l.he steam jet, although not an economical ventilator, may often be used to advantage for temporary purposes. Experiments with the steam jet have led to the following conclusions: 1. That the quantity of air put in motion by a steam jet depends upon the extent of surface in contact between the air and steam. 2. The intensity of the vacuum increases in direct proportion to the steam pressure. 3. The volume of air moved is in inverse proportion to the density of the air acted upon. 4. That the ventilating pressure obtained by forcing or exhausting are equal with equal steam pressure. It is evident that the lower the temperature of the air against which the steam acts, the greater will be the effect of condensation; therefore, the efiiciency will be greatest where the inside temperature is the highest and the jet placed in the upcast. Where a...show more

Product details

  • Paperback | 76 pages
  • 189 x 246 x 4mm | 154g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236787307
  • 9781236787309