gasses, i.e. Butane with a proportion of Propane mixed in, are available,
and may be used if straight Butane is unavailable. These come in a variety
of mixes ranging from 90/10 to 60/40 with one of the most common being
70/30. The figures refer to the proportions of the mix i.e. 70/30 contains
70% butane and 30% propane. If using mixed gasses, always choose the
one with the largest proportion of butane. The addition of propane slightly
alters the gasses properties. This can make the burner a little more
difficult to light when cold or after filling the gas tank. Always open the
regulator very slowly when lighting, and only just sufficient for ignition to
take place. Opening too much too soon may extinguish the flame until the
burner reaches normal operating temperature. The tiny jet in these units
can
become blocked by small particles of dirt making the burner difficult
to light, burn weakly at normal operating temperatures*, burn in the
smokebox or fail completely. If any of these should happen, clean out the
jet as follows. (* On very cold days, a burner may start off burning
weakly due to the temperature of the gas but should increase to its normal
level as the engine warms up. This is quite normal) . On Penrhyn versions,
it is necessary to remove the cab back. This is held on by two 8BA screws
and nuts at the top and two M2 nuts under the rear edge of the footplate.
Once all four have been removed, ease the top of the cab back gently
outwards until it clears the roof supports, then lift upwards to remove the
two threaded studs from the footplate.
Carefully, disconnect the gas pipe from the jet block using a 2BA spanner.
Note
when connecting or disconnecting the gas pipe and jet block, do not
use excessive force. Always hold the end of the gas burner near the air
holes to support it otherwise it is possible to cause damage by bending the
body. Slacken the screw retaining the jet block and slide it out to the rear.
Remove the jet from the jet block using a 4BA spanner. Wash out the jet
in fast evaporating thinner (Cellulose or similar).Blow through the jet
from the front, which should clear most blockages. Although the hole
through the jet is tiny, if you hold it up to the light you should be able to
see quite clearly if it is blocked or not. If in doubt, fit a new jet. A spare
gas jet is included with the toolkit. Do not use wire to clean the jet as this
can damage the precision hole and may upset the delicate balance of the
gas system. Reassemble in the reverse order, putting a small amount of
PTFE tape round the thread of the jet. Ensure all connections are tight.
15
