MAR. 5.

THE NEW ZEALAND GAZETTE.

The following three questions are for Ordinary Examination only :—

10. The flat crown plate of the combustion-chamber of a multitubular boiler is supported by double girder-plates and stay-bolts, the thickness of each girder-plate being ¾ in. and the distance between the girder centres 8 in. The pitch of the stay-bolts is 10 in., and the outer stays are 10 in. from the tube-plate and back plate of the combustion-chamber respectively. The maximum working-pressure is 200 lb. per square inch, and the distance between the tube-plate and the back end plate 40 in. Find the depth of the girder-plates, allowing a safe stress in the material of 11,000 lb. per square inch.

11. A steamship is fitted with three single-ended multitubular boilers, each having three furnaces. The grate area per furnace is 20 square feet, and 20 lb. of coal having a calorific value of 12,000 British thermal units per pound are burned per square foot of grate per hour. The efficiency of the boilers is 70 per cent., and dry steam is generated at 380 degrees F. from feed-water at 140 degrees F. What is the horse-power of the engines if 16 lb. of steam are used per indicated horse-power per hour ?

12. At the commencement of a voyage the boiler of a steamship contained 8,000 gallons of fresh water. In the course of the voyage, sea water which entered the hot well owing to a defective condenser tube was delivered with the condensed steam to the boiler, the leakage being equal to the quantity of fresh make-up feed supplied prior to the occurrence of the leak. Two days after the leakage occurred the density of the water in the boiler was found to be 1 oz. per gallon. If 900 gallons of feed-water were pumped into the boiler every hour, what was the number of gallons of sea water admitted per hour, assuming that blowing down was not resorted to, and that the level of the water in the boiler remained constant throughout the voyage ?

The following three questions are for Motor Examination only :—

13. The fuel valve of a Diesel engine closes at 0·1 of the stroke, and the clearance volume is 0·1 of the volume swept by the piston. The pressure of the gases during combustion, which takes place at constant pressure, is 600 lb. per square inch (gauge), and thereafter the gases expand adiabatically. The index to the expansion curve is 1·4 and the exhaust valve opens at 0·9 of the stroke. What is the pressure of the gases when exhaust begins ?

14. In an oil-engine 32 per cent. of the total heat of the fuel is lost in the exhaust gases, 28 per cent. in the cooling-water, and 5 per cent. in radiation. The mechanical efficiency of the engine is 80 per cent. and the calorific value of the fuel 19,000 British thermal units per pound. What is the fuel consumption per brake horse-power per hour ?

15. The area of the low-pressure cylinder of a two-stage single-acting air-compressor is 400 square inches, the length of the stroke 20 in., the speed 100 revolutions per minute, and the clearance volume 0·005 of the volume swept by the piston. Air enters the low-pressure cylinder during the induction stroke at atmospheric pressure (15 lb. per square inch), and is delivered to the intercooler at 120 lb. per square inch. Find, neglecting all losses, the output of the compressor in cubic feet of free air per minute. (Note.—The index to the compression and expansion curves is 1·4.)

EXAMINATION IN ENGINEERING KNOWLEDGE.

Form to be filled up by all candidates at the examination :—

Port:…………… Class for which examined :………………
Date:…………… Candidate’s name.………………

Give a brief account of your technical education, stating what science and engineering subjects you have studied, and what certificates you hold in these subjects.

Mention the technical schools you have attended, and the length of time spent at each.