MICROPUMP, INC.
A Unit of IDEX Corporation
PO Box 8975, Vancouver, WA 98668-8975 • Phone: 360/253-2008 • Fax: 360/253-8294
MICROPUMP
LIMITED
A Subsidiary of Micropump, Inc.
2 Howard Road, Eaton Socon, St.
Neots, Cambridgeshire, PE 19 8ET England, • Phone: 011-44-1480-356600 • Fax: 011-44-
1480-
356300
Page 14 of 33
2.4.1.2.2 Connect Model 668-400-2 into test setup as shown in Figure C.
Mount pump with pressure regulator screw in up position and motor
pointing down to facilitate adjustment. Open valve 1 completely
and valve 2 partially. Energize pump to establish initial system
pressure. Disable pressure switch by holding down starting button
during entire adjustment if necessary. Gradually close valve 2 and
allow system pressure to stabilize after valve 2 is completely
closed. Set pressure regulator for a 25 psi (1.73 bar) reading on
pressure gauge by loosening nut and turning pressure regulator
screw. Turn screw in to increase pressure and out to decrease
pressure.
2.4.1.3 Pressure Switch Assembly Adjustment
2.4.1.3.1 This adjustment allows system pressure to control motor operation
automatically at higher pressure, preventing pump from pumping
dry at low pressure.
Note: Pump automatically shuts off at low pressure, 4 psi (.28 bar) to 8
psi (.55 bar), and requires manually re-energizing pump.
2.4.1.3.2 It is wise to consider shims in pressure switch cavity as a rough
adjustment, and setscrew on pressure switch assembly as a fine
adjustment.
2.4.1.3.3 Connect Model 668-400-2 into test setup shown in Figure C.
Mount pump with motor and pressure switch in up position. Open
valve 1 completely and valve 2 partially. Energize pump to
establish system pressure. Close valve 2 slowly until a 23 psi (1.59
bar) reading appears on pressure gauge. If pump shuts off before
reaching a 23 psi reading, back off setscrew on pressure switch
assembly using 0.050 inch (1.27 mm) hex key until pump re-starts
automatically; then continue to obtain a 23 psi (1.59 bar) reading.
At this reading, screw in setscrew until pump shuts off
automatically. Open valve 2 slowly to decrease system pressure.
Pump should restart at 12-20 psi (.83-1.38 bar). Continue
decreasing system pressure. Pump should automatically shut off
at 4 to 8 psi (0.28 to 0.55 bar) low pressure.
2.4.1.3.4 Adjustment involves adding shim(s) to pressure switch cavity
(install below spring) and repeating process in step 2.4.1.1.3. One
shim equals approximately 2 psi (.14 bar). Avoid using more than 2
shims. To add shims, remove two screws holding pressure switch
assembly to cylinder. Lift pressure switch assembly from cylinder.
Lift spring from cylinder. Place shim(s) in cylinder, replace spring
and pressure switch assembly, and re-install screws.
