AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

Freezing Points of Diesel Fuel

16th November 1962
Page 86
Page 86, 16th November 1962 — Freezing Points of Diesel Fuel
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

TOUR October 12 issue of The Commercial Motor, under the heading "Temperature Effects on Diesel Fuel," reports me as quoting freezing points in respect of diesel fuel which are unrealistic and with which I cannot be associated. This, I feel certain, is due to some confusion in the interpretation of temperature scales.

The substance of my observations on this subject referred to degrees of frost—not degrees Fahrenheit. Thirty degrees Fahrenheit was certainly quoted and associated with the presence of water in the fuel (and it should, of course, be free from this contamination) freezing and causing fuel filter blockage.

a48

With regard to the summer grade of automotive diesel fuel, I indicated that separation of wax may begin at four to five degrees Fahrenheit of frost (27°F to 28°F), not at 40°F to 45°F as reported. I also stated that winter grade fuel gave satisfactory performance down to about 20 degrees of frost, again not at 20°F as shown in your article.

With regard to the effect of changing from summer to winter grade fuel, I said that fuel consumption is related to specific gravity and that a reduction in specific gravity could be associated with increased fuel consumption. This did not refer to a difference in specific gravities between summer and winter grades, in fact automotive diesel fuel marketed by my company is guaranteed to exhibit the same specific gravity for both grades.

Finally, I notice that page 54 of the same issue of your . journal carries an item that quotes identical temperature figures to those attributed to myself. In this case the author is Mr. D. W. Jacquest of Diesel Smoke Control Ltd. Does this indicate an accidental typographical error?

Guildford, Surrey. L. P. F. DRAKE, Technical Sales Representative.

[I have read with interest Mr. L. P. F. Drake's letter in which he refers to "Temperature Effects on Diesel Fuel," published in the October 12 issue of The Commercial Motor. Mr. Drake's comments on diesel-fuel " freezing " temperatures which were quoted in the news item were made in reply to questions raised by me during the discussion of his paper, "Fuel Developments," at a meeting of the Institute of Road Transport Engineers on October 9, which I covered for The Commercial Motor.

In my first question I stated that "a well-known authority on diesel smoke" had given 30°F (-1.1°C) as the freezing point of diesel fuel and 40°F to 45°F (4.4°C to 7.1°C) as the temperature at which wax formed. I emphasized that the validity of these figures had been challenged by the London Office technical staff of The Commercial Motor (because 30°F appeared to be an unrealistically high freezing temperature) but had been confirmed by the authority in question.

I was, of course, referring to Mr. D. W. Jacquest, who was quoted in the article, "Causes of Diesel Smoke," published in the same issue. In the reference in his letter to Mr. Jacquest's claims, Mr. Drake suggested the figures might have been included in my report of the I.R.T.E. meeting by "accidental typographical error." This is not so, in fact I welcomed the opportunity to obtain confirmation of Mr. Jacquest's statements from an independent authority.

Mr. Drake may not have understood that I had in fact said " 30°F ", and "40°F to 45°F" and not referred to degrees of frost but his reply confirmed the statements I quoted and was as reported in the October 12 issue. The figure he gave for the freezing point of winter fuel of 20°F, I naturally assumed indicated a thermometer reading (which was the term in which my question was put) rather than 'degrees of frost.

Regarding the effect of changing from a summer to a winter grade fuel on consumption, I recall that a member of the Institute asked whether the use of Winter fuel increased consumption and that Mr. Drake's reply Was very short. It was definitely in the affirmative.

In a telephone conversation on November 2 with the chairman of the I.R.T.E. meeting, he stated that there was no doubt in his mind that my question referred to a " freezing " temperature of 30°F. He recalled that the question implied snrprise that such a high temperature should have been given by an authority on the subject. He assumed that I wished to obtain confirmation of the figures given by the authority quoted.

As there is such a large difference between Mr. Jacquest's figures and the corrected figures given by Mr. Drake, it seems desirable to obtain the ruling of a third authority on the subject. I understand that the lower the " freezing " point of diesel fuel the higher the cost per gallon, but I have been unable to authenticate this claim,—P,A.C.B.1


comments powered by Disqus