Doosan D20G, Service Manual

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G424F(FE) Service Manual Chapter 6. LPG FUEL DELIVERY SYSTEM 183
Figure 34. Secondary Stage Test Connection
Pressure Test
Primary Stage Test Hardware
1.
Shop air pressure regulator adjusted to 100 psi
2. Shop air hose fitting (1/4” NPT to air hose)
3. Air hose
4. Test gauge fitting (1/16” NPT x 1/4” hose barb)
5. Vacuum hose or vinyl tubing
6. 0-60” WC Magnehelic gauge (inches of water
column)
Primary Stage Pressure Test
1.
Remove the primary test port plug from the side
of the regulator and install the 1/16” NPT hose
barb fitting (Figure 35).
2. Connect a compressed air line (shop air ~100psi)
to the liquid propane fuel inlet of the N-2007
regulator (Figure 35).
Figure 35. Primary Stage Test Connection
3. Apply compressed air, wait for air to exit the hose
barb in the test port, and then connect the
Magnehelic gauge (Figure 36) to the hose barb
using the vacuum hose or vinyl tubing. This
prevents the gauge from reading maximum
pressure due to the large velocity of compressed
air entering the primary chamber.
4. Make sure there is no leakage at any of the
fittings. The static pressure should read between
40-60” of water column on the Magnehelic gauge
and maintain a constant pressure for 60 seconds.
Figure 36. Magnehelic Gauge Connection to Hose
Barb
5. If the pressure reading begins to increase, a leak
is most likely present at the primary valve, either
the primary valve o-ring or the valve itself. If a leak
is present the regulator should be replaced.
6. If the pressure begins to decrease, the secondary
seat is probably not making an adequate seal and
is leaking. The regulator should be replaced.
7. If the test is successful, re-install the primary test
port plug and check the fittings for leaks. See
Chapter 5 for installation of the N-2007 regulator.
NOTE : The N-2007 primary stage pressure can
also be tested at idle on a running engine. The N-
2007 primary pressure should be between 40 inH20
(99.6mbar) and 55 inH20 (137 mbar) at 750 rpm,
idle.