WPI MPS-4, Instruction Manual

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14 World Precision Instruments
with a piece of tubing. If water flows through the µ-manifold and valve console
separately, try raising the syringe holder or shortening the manifold output
tubing.
5. The MPS-4 system is designed to work with aqueous solutions. Fluids that are
more viscous than water might not flow through the µ-manifold.
NOTE : If you have a problem/issue with that falls outside the definitions of this
troubleshooting section, contact the WPI Technical Support team at 941.371.1003 or
technicalsupport@wpiinc.com.
SPECIFICATIONS
This unit conforms to the following specifications:
Base .........................................................................................................White plastic over metal
Number of Perfusion Channels ...................................................................................................8
I.D. of Micro-perfusion Head Tubing ....................................... MP-1 100 µm; MP-4 250 µm
Dead Volume for Perfusion Head ..................................................................................<100 nL
TTL Triggering Inputs ..................................................................High: +3 ~ 5 V; Low: 0 ~ +1 V
Channels Control Level ..................................................................ON: +3 ~ 5 V; OFF: 0 ~ +1 V
Maximum Flow Rates (gravity fed) ................................ 100 µm ID tip, 8 µL/min. at 50 cm
............................................................................................250 µm ID tip, 500 µL/min. at 50 cm
Packing Weight.........................................................................................................................<8 kg
Packing Volume ...............................................................................................680x210x170 mm
APPENDIX A: DETERMINING FLOW RATE
Theoretical Calculation
The relationship of flow rate to the height of the liquid column and inner diameter of
the capillary tubing can be accurately predicted with the Hagen-Poiseuille equation.
F = C (d
4
PV/L)
F = flow rate in µL/min
P = pressure in mmH
2
O
L = length of capillary tubing in mm
V = viscosity of the perfusion media in cps
d = diameter of the capillary tubing in micrometers (µm)
C = constant (1.3765 x10
-8
).
In most biological systems, the fluid has approximately the same density as pure
water, so P is equal to the height of the liquid column in mm. The viscosity of most
biological perfusion solutions can be considered as one. Since the flow is proportional
to the fourth power of the tubing diameter, the restriction of the plastic tubing to
the flow can be ignored. We only need to consider the diameters and lengths of
the quartz tubing, and the fluid passages leading up to the 8 to 1 junction. A good
approximation of the resistance of the junction can be obtained by removing the
tubing from one of the 8 manifold inputs, and turning on one of the other channels.
Take the calculated flow resistance and divide it by two.