STANDARD LUBRICATING OIL SYSTEM FOR GEARED TURBINES. 249 



(e) Temperature — Viscosity curves for approved lubricating oils. Drawing 

 E-iiooo-ii. (Plate 109.) 



A. General. — i. Technical Order No. 75, as issued on September 16, 1918, 

 and its amendment of November 8, 19 18, provided for certain features which were 

 necessary precautionary measures while the country was at war, and which the 

 attached specifications and other enclosures will eliminate. It has also been found 

 that there has been a tendency in some quarters to follow the diagrammatic plan, 

 document d, as though it were a working drawing, and not merely an outline, as 

 it was intended. 



2. Due to the urgency of the situation, and for the sake of brevity, little space 

 was devoted in the first issue of Technical Order No. 75, and its amendment of No- 

 vember 8, to explanations or reasons why certain provisions were made. It is be- 

 Heved that the documents hereto attached will not only set forth requirements 

 clearly but will satisfactorily explain the reasons for their necessity. 



B. Departure from Previous Order. — The departures in this amendment from 

 Technical Order No. 75, and its amendment of November 8, are in general as 

 follows : — 



1. Suction strainer has been omitted. This strainer was originally intended as 

 a precautionary measure against sabotage, and to prevent foreign matter, left in the 

 system through carelessness, from entering pumps, and thereby causing serious 

 damage. The ending of the war, and the general adoption of an effective method 

 of cleaning the system, before trials, have rendered the use of this strainer un- 

 necessary. 



2. Two reserve tanks have been omitted. Extra reserve tanks were required 

 so that, in the event of the two gravity tanks being rendered useless by gun fire, 

 the reserve tanks could be used as gravity tanks. Another reason was the neces- 

 sity for carrying a large oil reserve due to the impossibility of securing suitable 

 oil in foreign ports. 



3. By-pass in oil line for the purpose of by-passing gravity tanks, and pumping 

 direct to supply line, has been omitted. This connection was provided so that, in 

 the event of gravity tanks being shot away, oil could be pumped directly from drain 

 tank to system, but it is no longer necessary. 



4. Gauge type indicator with electric contacts in discharge line, between pumps 

 and discharge strainer, has been omitted. With increasing familiarity of the oper- 

 ating force with the system, this additional safeguard is now believed unnecessary. 

 Ordinary pressure gauges reading from o to 100 pounds should be installed in their 

 place. Float switches in gravity tanks and accompanying electrical arm system have 

 also been omitted. 



5. The overflow from top of gravity tanks has been changed to side of tanks 

 as near the top as possible. Experience with systems installed with overflow dis- 

 charging from the top of tank proved that the air was not satisfactorily released 

 through the vent, due to lack of space at the top of tank for this purpose. The new 

 arrangement has been found to work satisfactorily in service. 



6. Sight flows and direction indicators of any kind have been eliminated from 

 supply line inasmuch as a practical device is not generally procurable. 



