Setting Up Temperature And Temperature Limit Controllers; Temperature Controller - Brooks Instrument DLI Manual De Instalación Y Funcionamiento

Section 2 Installation
®
Brooks DLI Vaporizer System
Table 2-1 Flow Rate Guidelines Without and With Gas Heater
Brooks Gas Flow Controller Size
Size 0 (for example, SLA5850)
Size 1 (for example, SLA5851)
Size 3 (for example, SLA5853)

2-11 Setting Up Temperature and Temperature Limit Controllers

2-11-1 Temperature Controller

2-8
well below 0°C. It might be necessary to heat the carrier gas once it has
been dropped to the specified inlet pressure of the vaporizer. Table 2-1
provides generic guidelines where you should consider heating the
carrier gas.
• Inlet carrier gas can be managed by heat tracing the gas inlet piping or
by the use of a self-contained gas heater. Two or more heaters can be
used in series or parallel for higher flow rates. (One source of gas heaters
can be found at the Calco Controls Inc. website http://
www.calcocutaways.com/ pdf/mcilrath1c.pdf.)
No Gas Heater Required
0–30 slpm
0–50 slpm
N/A
• Another method for managing carrier gas temperature is with the use of
a "sink". A sink acts like a large capacitor that charges and discharges
slowly. It consists of a tank and coiled tubing assembly that is submerged
in a fluid (for example, water or light oil). For very high flow rates, a plastic
55-gal drum with a coil assembly of ¾" stainless steel tubing 160 ft long
works well. Smaller sizes can be used for lower flow rates.
• It is common for the vapor temperature at the outlet of the vaporizer to
be less than the setpoint temperature of the vaporizer due to the effect of
evaporative cooling that takes place within the vaporizer.
When the vapor outlet temperature is required to be at or above the
vaporizer temperature setpoint temperature, it might be necessary to heat
trace the outlet piping of the vaporizer. Care must be taken not to overheat
the vapor as some chemicals will decompose when over-heated.
The temperature controller, whether a Watlow PID controller supplied by
Brooks Instrument, or a customer-supplied system, is used to set the
operating temperature of the DLI vaporizer. Temperature is reported to the
controllers by two Type K thermocouples attached to the vaporizer heat
exchanger, one for temperature control and one for limit control.
Vaporizer temperature is based on the specific chemistry and carrier gas
to be used. Each chemistry and carrier gas combination will require a
different temperature setting to achieve optimal vaporization. For best
results the ratio of precursor chemistry to carrier gas is a molar ratio of
1:1. Depending upon the fluid being vaporizer, the mass ratio of liquid:gas
can go as high as 12:1. Please consult with a Brooks applications
engineer for the proper mass ratio. This ratio accomplishes two goals -
achieve complete atomization of the precursor and achieve a favorable
partial pressure in the vaporizer allowing the precursor to stay well below
saturation. A default configuration file will be loaded into the PID controller
Installation and Operation Manual
X-VAP-DLI-Standard-eng
Part Number: 541B203AAG
Gas Heater Required
N/A
51–100 slpm
100–2500 slpm
May, 2016