Metallisation MK 73, Operating Manual / Spare Parts List

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Page 32 of 64
4.5 The Gas Head & Main Valve
4.5.1 Removal & Dismantling
Referring to DIAG 5 and DIAG 6, use the following procedure to
dismantle the Gas Head and Main Valve Assembly, when necessary:

Remove the Gas Head (V) and Valve as a unit, by unscrewing the 2 Gas
Head Fixing Screws (A) .

Slide the Front Wire Guide (B) from the Gas Head (V) , discardin
g ‘O’
Rings if damaged.

To separate the Gas Head from the Valve, unscrew the Air Union (C) and
Oxygen Union (D) from the Valve and remove the Valve to Gas Head
Fixing Screws (E) . Discard the Gasket (X) .

Remove the four Diaphragm Housing Screws (G) (2 not shown), located at
the front face of the valve and separate the Diaphragm Housing (H) from
the Cam Spindle Housing (I) .

Remove and discard the Valve Diaphragms (J) .

Slide the Air, Oxygen, and Gas Plungers (K) including the Pilot Gas
Plunger (S) from the Cam Spindle Housing (I) .

Gently extract the Valve Lever Plug (L) from the Cam Lever (M) . Unscrew
the exposed Valve Lever Screw (N) and remove it. Remove the Washer
(O) , Cam Lever (M) and Lever Return Spring (P) , taking care not to lose
any of these parts.
DIAG 6
WHEN & WHY?
The Gas Head and Main
Valve Assembly should
only be dismantled when it
is absolutely necessary.
For example:

When replacing the
Front Wire Guide.

When the Pistol
Valve needs
inspecting.

The Heat Shield
needs attention.

The Drive Box needs
repairing.

When changing Wire
Diameters.

If difficult to turn or in
case
of Spindle
binding.

Gas leaking through
Valve.

Valve is sticking.

Periodically for
inspections (every 6
months).

After a flashback.

If gas flows are low.
DIAG 5
C
D
H
G (2x Screw)
E (2x Screw)
I
J
(3x Valve Diaphragms)
K
(3x Plungers)
L
N
M
O
P
R
Q
T
U (3x Seals)
S
Y
X
A
B
W
V