Hi all, i'm looking for a defini

[phex]

Hi all,

i'm looking for a definition text on the term "blending RVP"(RVP = Reid Vapor Pressure).

It is used in conjunctioon with fuel blends, especially when its about oxygenated fuels. Although i do know its meaning, i need to know a technical standard (API, ASTM, DIN, EN...) as a trusted source.

i'll explain what i'm talking about in a short example:

RVP (if measured after ASTM D5191) of Ethanol is about 2.3 psi. when blended into fuel, it has a blending RVP of 18 psi. this comes from polarity of the ethanol molecule and describes: if i blend 90 vol-% fuel stock and 10 vol-% ethanol, the ethanol would have to have 18 psi RVP to reach the real mixture RVP IF the mixture rvp would result from linear correlation.

and i need that above from "official source" as basis for guarantees.

thanks for your help,
chris

 

[25362]

Coud this be of help ?

http://www.ec.gc.ca/transport/publications/ethgas/ethgas4.htm

 

[phex]

thanks alot, this is a first step =)

although it doesn't really speak of regulations or standards, it comes from official side, and as such should be of help.

again, thanks,
chris

 

[hotgas]

Who was Reid and how is petroleum Reid Vapor Pressure (RVP)any different from "normal" vapor pressure? All the environmental standards for reformulated gasoline refer to RVP.

I thought I was on to something when I borrowed The Properties of Gases and Liquids, 5th edition by Bruce Poling, John Prausnitz and John P. O'Connell, published in 2001. The original author was Robert Reid. He elected not to participate in the 5th edition. Is he the inventor of RVP? The book does not talk about RVP.

Please give me a history lesson.

 

[25362]

We all know that spark-ignition engine fuels are mixtures of many HCs, sometimes including oxygenates(reformulated gasolines) and have a range of BPs and VPs.

VPs can be measured in different ways. One of the most common measures of fuel volatility was the VP at 100^oF measured in a chamber having an air to liquid fuel ratio of 4:1 aka the Reid Method.

The ASTM D 323 (aka Reid Method) was used for hydrocarbon-only gasolines and their blends, but not for gasoline-alcohol blends because of water traces effects on the alcohol leading to incorrect results. Even for only hydrocarbons the RVP results aren't in agreement with the true VPs as calculated from HC analysis. This is due to evaporation of light HCs during the determination of the RVP. A true VP is about 5-9% higher than the figures obtained by this test.

Specification D 4814 for Automotive Spark-Ignition Engine Fuels doesn't list the Reid Method as acceptable.

A new method D 4953 maintaining dry conditions has been developed for gasoline and gasoline-oxygenate blends (Dry Method).

When dealing with just gasolines D 323 and D 4953 don't show any statistically different results. Two other methods used with gasolines and gasoline-oxygenates blends using advanced instrumentation are D 5190 and D 5191, both being more precise (repeatability and reproducibility) than
D 4953.

As for history, I believe the Reid Method was adopted in the early 1950s following work by a chemist named Clement Reid, but I'm not entirely sure about that.

A reasonable tutorial on the gasoline subject can be found in:

http://www.geocities.com/TimesSquare/Alley/7026/autos_gasoline-faq_part1.html

 

[Mutt]

Some calculation methods and bit of background given in "How to estimate RVP of blends", Hydrocarbon Processing, August 1992, Vazquez-Esparragoza et al.

I used their methodology for estimating RVPs of various'exotic' blends as a VBasic insert into spreadsheet as I don't have access to fancy software like Aspen - does not handle polar compounds well, to be expected!

Specifically want data on ethanol blending, I found following quite good :

http://www.ec.gc.ca/transport/publications/ethgas/ethgas4.htm