U.S. Boiler Company MPO - IQ, Service Instructions Manual

Page: 46 / 92

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Figure 30: Two Pipe Oil Lines
C. TWO PIPE OIL LINES
1. For two piped systems, where more lift is required, the
two-stage fuel unit is recommended. Table 7 (two-stage)
and Table 8 (single-stage) show allowable lift and lengths
of 3/8 inch and 1/2 inch OD tubing for both suction and
return lines. Refer to Figure 30.
2. Follow the oil pump manufacturer’s recommendations
on the proper connections for a two pipe system. Some
manufacturers require the insertion of a bypass plug.
3. Under no circumstances is a manual shutoff valve to
be located on the return line of a two pipe system.
Accidental closure of the return line will rupture the oil
pump seals.
TABLE 7: TWO-STAGE UNITS (3450 RPM) -
TWO PIPE SYSTEMS
Lift "H"
(See Fig. 25)
Maximum Length of Tubing
"H" + "R" (See Figure)
3/8" OD
Tubing (3 GPH)
1/2" OD
Tubing (3 GPH)
0' 93' 100'
2' 85' 100'
4' 77' 100'
6' 69' 100'
8' 69' 100'
10 52' 100'
12' 44' 100'
14' 36' 100'
16' 27' 100'
18' --- 76'
TABLE 8: SINGLE-STAGE UNITS (3450 RPM) -
TWO PIPE SYSTEMS
Lift "H"
(See Fig. 25)
Maximum Length of Tubing
"H" + "R" (See Figure)
3/8" OD
Tubing (3 GPH)
1/2" OD
Tubing (3 GPH)
0' 84' 100'
1' 78' 100'
2' 73' 100'
3' 68' 100'
4' 63' 100'
5' 57' 100'
6' 52' 100'
7' 47' 100'
8' 42' 100'
9' 36' 100'
10' 31' 76'
11' 26' 100'
12' 21' 83'
13' --- 62'
14' --- 41'
VIII. OIL PIPING (continued)