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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Summary of comparative and pressure tests carried out on oil coolers in connection with Ph.III.

Identifier  ExFiles\Box 131\1\  scan0160
Date  7th December 1935
  
To E.{Mr Elliott - Chief Engineer}

Hs{Lord Ernest Hives - Chair}/Std.19/KW.7.12.35.

Summary of Tests Carried out on Oil Coolers
in connection with Ph.III.

(1) Cooler matrices to LeC.3756 and LeC.4386, and also a Buick matrix have been compared on a cooling basis. The ratio of the heat dissipations are respectively LeC.3756 - 1.0, LeC.4386 - 0.64, Buick - 1.04, the heat dissipation in the case of LeC.4386 matrix being considerably less than the other two.

(2) LeC.3756 and LeC.4386 coolers have been compared for back pressure. Under similar conditions the back pressure of the latter is approx. 50% of that of the former. This effect is of no importance with the oil hot. With the oil cold it results in a drop of maximum pressure on cooler from 135 lbs/sq.in. to 125 lbs/sq.in., i.e., 7.5%.

(3) The maximum pressures to which the coolers are subjected are (a) hot - 60 lbs/sq.in. (b) cold - 135 lbs/sq.in.

(4) Original cooler to LeC.3756 was tested for pressure and leakage occurred at three points, at the joint between the outer ring of tubes and the case at 100 lbs/sq.in. - this is not really representative of this cooler's strength as it was hand soldered and not dipped.

(5) New type cooler to LeC.4386, which had been properly soldered (dipped) was pressure tested. Leakage occurred at 180 lbs/sq.in. (oil cold) at junction of outer ring of tubes to case.

(6) New type cooler to LeC.4386 (similar one to that tested in (5) was pressure tested with hot oil. Leakage occurred at 100 lbs/sq.in. with oil temp. of 130°C. This time the leakage was at the centre of the matrix at the junction between two adjacent tube ends. This may have been due to poor soldering or to the fall of Solder strength with temperature rise.
  
  


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