Bronkhorst®
Instruction Manual Controlled Evaporator and Mixer
9.17.126A
14
Gas entrapment by dissolution can be minimized by taking one of the following measures:
·
Use a container or vessel with a membrane to pressurize the liquid; the membrane separates the gas from the liquid, so it
cannot dissolve.
·
Use a pump to feed the liquid. Note, however, that some pumps have a large internal volume, which lengthens the start-
up time of the system. Also, some pump types (e.g. gear pumps) can cause cavitation, which introduces gas bubbles,
exactly what was to be prevented.
If direct pressurization of the liquid with a gas is inevitable, these measures can keep gas dissolution to a minimum:
·
Use a gas with a low solubility to pressurize the liquid (for instance Helium)
·
Keep the gas pressure on the liquid as low as possible
·
Relieve the gas pressure from the liquid when the CEM system is not in use
2.5.4
Liquid vessel size
The liquid vessel should be large enough to provide a stable flow for a sufficient amount of time between refills. Purging or
flushing the fluidic system can consume a relatively large amount of liquid; take this into account when selecting a suitable
vessel size. The table below gives an indication of the liquid consumption, based on different flow rates:
Flow rate
Liquid consumption
g/h
mg/min
g per work week (40 hours)
g per week (24x7 hours)
0.1
1.6
4
16.8
1
16
40
169
10
160
400
1680
100
1600
4000
16800
2.6
Media compatibility
The wetted parts of the CEM are made of SS316 (heater) and SS304 (mixing valve). The standard sealing material for the
mixing valve is Kalrez®, which is compatible with a wide range of chemicals.
Before deploying the CEM with any other media than specified at ordering time, be sure that the media are compatible
with the wetted materials and sealing material. Accumulation of corrosion matter on the tubing interior can easily
destabilize the flow, especially with (extremely) low flows.
