Fritz et al,
I previously mentioned the sight glass on the Merlin Hunslet--it is a
plastic "plate' glass sandwiched between two brass plates, with gaskets
and fastened with screws. The tubes from the boiler to the sight glass are
straight and oversize--5mm outer dia. There is no problem with
bubbles--there is a red line in the back making reading easy--and the glass
is positioned where it is easy to read., So Merlin loco works knew how to
do it almost 20 yrs ago! Perhaps another manufacturer can do the same
today--more expense--yes, but worth it, wish every loco I have had the
same arrangement. More advantages; easy to take apart and clean and no
breakage problems!
Geoff.
>Has anyone considered using plastic in lieu of glass? In one of our biology
>lab experiments we have our students measure water in a glass graduated
>cylinder and then repeat the measurement in a plastic (Nalgene,TM) graduated
>cylinder. With glass you need to read the "bottom" of the curve, called the
>meniscus. With plastic this is not necessary as there is no "wetting" and
>therefore no capillary action. Clearly (no pun intended) such a plastic
>tube would have to be able to withstand the heat and pressure of steam.
>Here I can offer no information. Any "materials" experts out there should
>be able to provide the right info. May save a lot of headaches!
>
>Keep your steam and sap up!
>
>Fritz Brohn
>
