Hydraulic Circuit Design - Levitronix PuraLev i100MU User Manual

3.4 Hydraulic Circuit Design

Following general design rules help to operate the pump system optimally considering efficiency, optimum
priming behavior and low shear forces:
1. The general rule for minimum shear forces and optimum priming behavior is to minimize the pressure drop in the inlet circuit
and avoid negative pressure at the inlet of the pump head.
2. Minimize tubing length at the inlet of the pump head and maximize the ID (not smaller than the pump head inlet ID of 9.5 mm is
recommended). This reduces the pressure drop and the tendency of cavitation.
3. Avoid any restrictions, valves, elbows, bended tubing and sharp edges at the inlet circuit of the pump head, which potentially
causes cavitation resulting in higher shear forces and bubble collection in the pump head with the danger of priming loss.
4. Choose correctly aligned sealing rings and fitting adaptors to connect tubing to the in- and outlet of the pump head. Consult the
dimension drawings of the sealing ring and fitting adaptor manufacturer and check with the in- and outlet ID. Miss-aligned sealing
rings and fittings can be the cause of increased shear forces and cavitation effects.
5. Place the pump at the lowest point of the hydraulic circuit. Optimum is as much as possible below a tank or reservoir. This
optimizes priming behavior and keeps the inlet pressure positive for low shear forces.
6. Keep the liquid level in the reservoir tank or bag as high as possible, which increases the inlet pressure of the pump head and
minimized heat up of the liquid.
7. In general the pump system placement and hydraulic circuit shall be designed that gas bubbles can leave the pump housing
and that the pump head remains primed.
8. To minimize heat up of the liquid the overall pressure drop in the hydraulic circuit shall be reduced as much as possible.
9. It shall be avoided to pump longer times against a closed valve, which can cause heat-up of the liquid and higher shear forces.
10. At flows < 1 l/min it is recommended to use a bypass loop to assure that sufficient flow runs through the pump head to wash-
out gas bubbles and avoid heat stagnation.
11. At higher liquid temperature the rules mentioned above become more important due to higher cavitation tendency of the liquid.
12. As the pump heads and the fittings are made out of plastics the usage of 3-part clamps instead of 2-part clamps (see Figure
20) for in- and outlet connection is recommended to prevent asymmetric stress during high temperature treatments like SIP
(steam in place) or autoclaving causing sealing and leakage issues.
13. Load and stress at the inlet and outlet by heavy tubing and improper mounting alignment shall be avoided (see Figure 21) as
this can cause leakage issues due to distortion of the plastic pump housing.
Figure 21: Avoidance of stress forces and torques at the inlet and outlet of the pump head
®
Contact the Levitronix
support on the design of the hydraulic circuit.
PL-4075-00, Rev02, DCO# 20-275
Recommended
Figure 20: 3-part clamps versus 2-parts
Force/torque stress
at the in- and outlet
of the pump housing!
Technical Service department (see Section 8) for more detailed considerations and
User Manual for PuraLev
Heavy tubing at
in- and outlet of pump
Tubing fixation/support to avoid
load at in- and outlet of pump system.
®
i100MU
www.levitronix.com
Can cause assymetric
stress with sealing issues
Pump
17