Metallisation MK 73, Operating Manual / Spare Parts List

Page: 47 / 64

Page 47 of 64
Note (b)
This type of reading, with both floats equally low and pressures correct can be due to:

Restricted nozzle holes or undersized air nipple or dirty air nipple or too much air
pressure.

Restricted mixing block holes.

Pressure gauges reading too high or extra-long hose lengths being used.
In all cases the pistol will be quite usable if flowmeter readings are within 15% of
recommended readings. Spray throughput may be slightly reduced.
Note (c)
Readings of this type show an incorrect ratio of oxygen/gas mixture. With standard
type nozzle assemblies, i.e. 1015, 1020, 1010 etc., the imbalance can be easily
corrected by raising or lowering the oxygen pressure by a small amount. With other
nozzle assembly types, the mixing block holes should be checked for restrictions.
Note (d)

Procedure for Fine Spray

Set the flowmeter markers to: Gas 1.5, Oxygen 1.5

Set air to 50 psi, propane to 20-30 psi, oxygen to 34-45 psi
(Note: The higher gas and oxygen rates give slightly higher spray rates, however this does
lead to hotter deposits).

Open valve and check that gas float is spinning:
(A vertical tube and slow valve opening may be needed) (If gas float are not spinning freely,
then reading will be approximately 0.2 divisions too high)

Adjust oxygen pressure to bring to top of the oxygen float to the same position (relative
to the top of the gas float is to the gas marker).
Note : If the tops of the floats are higher than 2.0 on the tube scale then lighting may
be difficult.
NB: If the top of either float is lower than 1.5 then check mixing block for restricted gas holes.

Light the Pistol and start the Wire Drive.

If gas float is spinning freely, adjust oxygen pressure to position top of
oxygen float to same relative position as top of gas float.

Adjust wire speed if necessary

Close valve and stop wire
NB:
This pistol may be re-lit and used without further as adjustments through an occasional
check on the flowmeter reading, while spraying, is advisable.
NOTE: Excessively HIGH or LOW flows may indicate leaks or blockages in the Supply
lines to the pistol.