System Purging; Temperature Management Of The Vaporizer Carrier Gas, Liquid Inlets, And Vapor Outlet - Brooks Instrument DLI Manual De Instalación Y Funcionamiento

Installation and Operation Manual
X-VAP-DLI-Standard-eng
Part Number: 541B203AAG
May, 2016

2-9 System Purging

2-10 Temperature Management of the Vaporizer Carrier Gas, Liquid Inlets, and Vapor Outlet

Prior to the introduction of precursor to the vaporizer, it is important to
eliminate all atmosphere (air) and moisture (except for water vaporizers)
from the process lines and vaporizer and replace them with an inert gas,
as most precursor chemistries react with air and/or moisture.
Any time the line is opened or a new precursor is introduced, it is
important to purge the system. It is common to use both a non-
contaminating solvent like hexane and a dry gas like nitrogen to clean and
purge the system. It is the user's responsibility to select purge liquids and
gases that are compatible with the process / precursor to be used. It is
extremely important that when using any hydrophobic fluid that you use
an appropriately-sized hydrophobic particle filter upstream of the liquid
flow controller. We do not recommend sintered or stainless steel filters in
this application due to the difficulty in eliminating all moisture from the
surface of the filter media.
Temperature management of the incoming liquid, incoming carrier gas
and the vapor outlet is critical in producing and maintaining good quality
vapor.
• The liquid and carrier gas should be at a temperature of not less than
20°C. Very high vapor pressure liquids may be an exception and require a
lower temperature.
• Carrier gas temperature management is very important. When carrier
gas flow rates exceed 50 slpm, it is likely that the temperature of the gas
will drop below 20°C. Each gas has a different Joules Thompson
coefficient (http://chemengineering.wikispaces.com/
Joule%E2%80%93%C2%ADThomson+effect)and will yield a different
result. However, as the carrier gas is expanded from the source through
the gas delivery system of regulators, filters, and valves, it will expand
from the source pressure to the lower pressure required at the vaporizer
atomizer. Flow rates greater than 50 slpm can lower the gas temperature
Section 2 Installation
®
Brooks DLI Vaporizer System
2-7