Dover PSG Blackmer LGL158B Інструкції з монтажу, експлуатації та технічного обслуговування - Сторінка 5
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GUIDE TO UNDERGROUND TANK
APPLICATIONS
TANK
15 %
MIN.
LEVEL
Fig. 5 – Underground Tank Schematic
No.
Description
1
Dip Tube
2
Excess Flow Valve
Control Valve - Full
3
Flow Ball
4
Strainer (Optional)
5
Inlet Piping
6
Pump Speeds
7
Back Check Valve
Control Valve - Full
8
Flow Ball
9
Bypass Valve
10
Priming Valve
11
Minimum Tank Size
* Blackmer PN: 455750
When pumping from an underground tank, the change in
elevation from the fluid level in the tank to the inlet of the
pump will cause significant vaporization of the fluid in the inlet
piping. For this reason alone, it is impossible to prevent
vaporization at the inlet of the pump for an underground tank
installation. However, there are many things that can be
done to minimize these effects. Refer to figure 5. See
Bulletin 500-002 "Underground Tank Application Guide" for
more detailed information.
INSTALLATION
9
BV
10
8
7
VAPOR
PUMP
6
5
4
3
2
1
3 "
LGL150 Series Pumps
2"
Fisher F190, Rego A2137A,
or equivalent
2"
2"
2"
1150, 1450, & 1750 RPM
Fisher G200-16, Rego A7794
(sight glass) or equivalent
1.5"
BV1.5"
Fisher F138* or equivalent
2,000 Gal (7570 liters)
501-K00
For an underground tank installation, the piping between the
pump and the tank is filled with vapor when the pump is at
rest. This vapor must be removed before the pump can
prime. Reducing the amount of vapor during startup and
operation will greatly enhance the pump's performance.
Inlet Piping Length
Keep the inlet piping as short as possible. Install the pump
directly over the tank and as close to the ground as possible.
Minimize the Number of Fittings
Every fitting, valve, and piece of straight piping causes a
pressure drop and adds to the startup vapor volume. Use a
minimum number of fittings on the inlet side of the pump.
Eliminate all possible elbows in the inlet piping by moving the
pump so that they will not be necessary. Size the inlet piping
per the table.
Strainers (4)
Suction strainers should not normally be used on
underground tank installations. The end of the dip tube
should be placed 2 – 3" (5 – 8 cm) above the bottom of the
tank. In applications with known high levels of contaminates,
install a strainer that is one or two sizes larger than the pump.
Vapor Priming Valve (10)
Install a vapor priming (excess flow) valve on the discharge
side of the pump, between the soft seat back check valve and
the pump. Refer to figures 5 and 6. The vapor excess flow
valve provides a path to return the vapors to the tank during
startup. When liquid flow is established, the vapor excess
flow valve will close. When piping the return line from the
vapor excess flow valve to the tank, ensure that there are no
low spots where liquid can collect. Pipe the vapor return line
to the vapor space in the tank, NOT to the liquid space of the
tank or to the inlet of the pump.
Soft Seat Back Check Valve (7)
Install a soft seat back check valve on the discharge side of
the pump as close as possible. A swing valve is preferred.
Refer to figure 6.
BACKCHECK
VALVE
Fig. 6 – Vapor Priming Valve and Back Check Valve
Page 5/12
BACK TO VAPOR SPACE OF TANK.
SLOPE HORIZONTAL PIPING
DOWNWARD TOWARD TANK.
VAPOR PRIMING VALVE
PUMP