Kubota DG972 E2, Applications Manual, Page: 32 / 93

2-4
3. CAUTIONS
[1] For safety (WG752 − GL, WG972 − GL, DG972)
• All fuel connections added to this engine must be installed by qualified personnel utilizing recognized procedures
and standards.
• The non-KUBOTA installed parts, such as hoses, fittings, piping, shutoff solenoid valve should be approved for
LPG (Natural gas) use and conform to UL, CSA, NFPA, MSHA and all other applicable standards.
• An approved, listed fuel filter (gas filter) and shutoff solenoid valve (for safety purpose for DG972, two valves)
must be installed between the LPG tank and Kubota LPG regulator with vaporizer before the Kubota gas
regulator.
• Two shutoff solenoid valves must shut off the gas when engine stalls (DG972).
• The following standards must be followed prior to installation: UL, CSA, NFPA and MSHA standards.
(1) Tightening torque and leak check for vaporizer and gas regulator
Each fitting must be sealed with approved joint sealant compound the joint must be installed to the gas entrance
of the regulator by screw with O-ring. And fittings and screw are tightened to the specified torque using a wrench
(driver), and leak check by a soap solution or its equivalent must be performed as shown in the below table.
Bubbles will indicate a loose connection.
TIGHTENING TORQUE AND LEAK CHECK PRESSURE
* NOT KUBOTA supplied
(2) Change the angle of LPG fitting of dual fuel carburetor and Gas fitting of
gas mixer
The fitting may be mounted on any position since it is not sealed. The nut may by loosened using a wrench. Fitting
may be changed to any specified angle. The nut should be tightened to the specified torque using a wrench as shown
in the below table.
TIGHTENING TORQUE
(3) Setting and vibration limits
Install the LPG regulator (gas regulator) in UPRIGHT position, it must be installed within 4G vibration level. If not,
it may not supply necessary LPG fuel to the engine.
DO NOT connect the extension hose with the air vent pipe of the gas regulator.
If do this, it may not supply necessary fuel to the engine.
(4) Starting the engine (WG752 − GL, WG972 − GL)
Do not move the choke lever, when LPG starting.
Otherwise, the vaporizer might brake down.
Fitting Qty. Size
Tightening torque Leak check pressure
Nm kgfm ft-lb kPa kgf/cm
2
psi
GL
LPG OUT
(VAPOR)
1 R3/8 29.4 to 58.8 3.0 to 6.0 21.7 to 43.4 > 9.8 > 0.1 > 1.42
LPG IN
(LIQUID) *
1 R1/4 19.6 to 39.2 2.0 to 4.0 14.5 to 28.9 > 1471 > 15 > 213
WATER
IN/OUT
2 R3/8 29.4 to 58.8 3.0 to 6.0 21.7 to 43.4 > 245 > 2.5 > 35.6
DG SCREW 2 M4 1.9 to 2.9 0.2 to 0.3 1.5 to 2.2 > 4.9 > 0.05 > 0.7
Fitting Qty. Size
Tightening torque
Leak check
Nm kgfm ft-lb
GL
LPG IN
(VAPOR)
1 M12x1.25 11.8 to 26.5 1.2 to 2.7 8.7 to 19.5 Soap solution or its equivalent
DG
GAS IN
(LOCK NUT)
1 M16×1 19.6 to 39.2 2.0 to 4.0 14.5 to 28.9 Soap solution or its equivalent