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MICRO-PUMP TECH TIPS
Customized Solutions
Pressure limits:
Although Micro-Pumps are capable of producing
outlet pressures of up to 5 psi (0.35 bar) while a dispense is taking
place, for optimal dispense accuracy, the pressure on both the inlet
and the outlet side of the pump should be kept between ± 0.5 psi
(0.035 bar), equivalent to a head of ± 12” (300mm) water.
During the pump’s up-stroke, suction is created on the inlet. Positive
pressure is generated at the outlet during the down-stroke. When
the pump is not actuated, it will shut-off flow as long as the pressure
on the inlet does not exceed the maximum holding pressure. To
ensure correct operation, pressure on the inlet side should never
exceed 2 psi (0.14 bar) even when the pump is in the closed position.
The check valves in the pump prevent fluid from flowing against the
intended flow direction.
OPERATING PARAMETERS & INSTALLATION TIPS
Output volume and accuracy:
A number of factors influence the
output volume of our pumps. In our factory the pump’s setpoint is
determined using the following test conditions:
•
Fluid: De-ionized water at 70°F/21°C
•
Fittings: Omni-Lok™ 1/4”-28 inverted cone fittings for the 120SP
and 130SP pump families and 5/16”-24 inverted cone fittings for the
150SP pumps (see page 13).
•
Tubing: PTFE tubing with the following dimensions:
• 120SP and 130SP pump families: Internal diameter
of 1/32”, 3”/8cm ≤ tubing length ≤ 14”/35cm.
• 150SP pumps: Internal diameter of 1/8” on the inlet and 1/16”
on the outlet, 3”/8cm ≤ tubing length ≤ 10”/25cm
•
Pressure: Negligible pressure on both the inlet and outlet ports.
•
Cycle rates:
• 120SP & 130SP pump families: 250ms on / 350ms off
• 150SP pump family: 250ms on / 750ms off
•
No air or gas bubbles in the line once the priming process is
complete. (See the Priming section on right)
If your application parameters deviate significantly from the above, you
may experience dispense rates that are different from the setpoint. In
that case, please contact Bio-Chem Fluidics to discuss your application
and we will make appropriate adjustments for you.
Priming:
Micro-Pumps must be fully primed prior to operation
to ensure that all air is removed from the pump cavity. Priming is
achieved by cycling the pump until no air bubbles are seen in the
dispense. This normally takes 30-60 seconds. Excessive air bubbles in
the dispense are generally caused by air leaks due to loose fittings -
check all the fittings in the system and tighten accordingly.
LeadWires:
As a standard all lead wires are PTFE coated. Lead wires
are provided with stripped ends for easy wiring into your control
system - refer to drawings on product pages for more details.
Different lengths and terminal connectors can be provided - refer to
customization notes below.
Orientation:
Pumps should be installed with the solenoid portion of
the pump pointing upwards, downwards or in a horizontal position
with the outlet on top. This ensures that any air in the system will
be evacuated quickly and also minimizes the effects of a pressure
head acting to keep the check elements open when they should be
closed.
We understand that many applications require customized solutions. Our design and prototyping expertise enables us to offer
simple modifications of standard products as well as completely customized designs. Over 90% of the Micro-Pumps we sell are
customized to one extent or another. Customizable options include (but are not limited to):
• Materials of construction
• Operating voltage
• Dispense volume
• Mounting options
• Tagging / labeling
• Length and/or style of connecting leads
• Custom manifolds
We look forward to working with you to meet your design engineering objectives!
Inlet
Outlet
Preferred mounting positions