RE: Olive Oil & Spica

[Hirsch <Catenary@domain.elided>]

Rich McCarty wrote:

>> ... but Wes Ingram told me that the best guess for the fluid inside
the thermostatic actuator on the Spica cars is a highly refined olive
oil! He said that nobody knows for sure, but a few chemists have looked
at it and olive oil is their best guess... <<

I've read some pretty weird things on the Alfa Digest, but this has
to one of the strangest.

First of all, think of what a TA does. A TA is two metal bulbs
connected by a small diameter tube. One of the bulbs is bathed in engine
coolant. The other bulb contains a piston. The length the piston extends
beyond the bulb is dependent on the temp. of the engine coolant. For a cold

engine, piston extension is small. As the engine warms the piston extension

increases.

Here are three reasons I can think of as to why the engineers
that designed the Spica injection system would not use olive oil
(even highly refined olive oil) in a thermostatic actuator (TA).

1) Olive oil freezes at about 21 deg F (-6 deg C). The TA must operate
over a wide temperature range, ca. -10 deg F to 140 deg F. Why use a
fluid that would not be effective at a temp. slightly below freezing?

2) In many ways the piston half of the TA acts like a tiny hydraulic slave
cylinder, so why not just use hydraulic fluid? It meets the temp.
requirement
given in 1) above and the price is certainly right. How well would olive
oil
work well as hydraulic (brake) fluid?

3) The TA contains rubber seals that must stand up to the TA fluid. Can you

imagine asking a counter man for an O-ring resistant to olive oil?

Finally, some years ago at an AROC convention I was at a tech session given
by Wes
Ingram where Wes asked people what they thought was inside a TA. One guy
suggested
mercury (!!!), another suggested water. Wes told us it was hydraulic
fluid -- essentially brake fluid. It made perfect sense to me then, it
makes
sense to me today.

Rich Hirsch
St Louis MO

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