SyriXus Series Pumps Installation and Operation Guide
Section 5 Continuous Flow Introduction, Installation, and Operation
5-16
EAR99 Technology Subject to Restrictions Contained on the Cover Page
5.5.4 No Check Valve
All Teledyne ISCO SyriXus series syringe pump models can use
SyriXus series syringe pump controllers or a standard Teledyne ISCO
D series syringe pump controller (refer Section 3.2.1 "Controller
Models").
Teledyne ISCO pumps are normally operated with a check valve in the
refill line to prevent backflow into the working fluid source reservoir
when the inlet valve is opened. This backflow results from the pres-
surized fluid on the pump side of the inlet valve causing fluid to flow
backward through the inlet valve into the supply reservoir when the
valve is opened.
To limit fluid backflow from the pump to the supply reservoir, one of
the following approaches are generally used.
1. The most common technique is to install a check valve in the
supply line. This approach works well with most common liquids,
but more viscous fluids are difficult to aspirate through a check
valve.
2. Another method is to pressurize the supply reservoir (perhaps
with a pressure pot), but this involves more hardware and is typ-
ically cumbersome to work with.
3. A typical approach is to delay the opening of the inlet valve to
allow the pressure to equalize across the valve before it is
opened. Teledyne ISCO syringe pumps provide a N
O
C
HECK
V
ALVE
(NCV) software feature to implement this delay.
The N
O
C
HECK
V
ALVE
(NCV) feature controls the opening of the
inlet valves such that, just prior to refill, the pump is
depressurized to a user specified value (pressure point) or for a
user specified time-out period (time point). This action reduces
the pressure in the cylinder before the inlet valve is opened.
NOTE
The check valve approach is generally required when the viscosity
of the working fluid is low, when working with gases or when the
working fluid changes phases when depressurized (like liquefied
CO
2
). In these cases, the depressurization of the pump may lead to
insufficient refills.
When the working fluid is viscous (more than 150 centipoise), the
check valve on the supply fluid inlet may create an undesirable
restriction during refill. The N
O
C
HECK
V
ALVE
(NCV) feature in the
SyriXus series controller allows the SyriXus series pumps to be more
smoothly operated without the refill check valve installed.
