Chromalox PQ431 - Manual (Page 2)

CAUTION: This vaporizer is not for use with water or ethylene
glycol and water mixtures as the heat transfer media. Check with
your local Chromalox Sales and Application Engineer to be sure
that you are using an accepted heat transfer media in this vapor-
izer or consult PQ301.
Note: When installing the vaporizer, allow a minimum of 3 feet for
removing heating element if, and when, necessary.
HYDRAULIC OR MECHANICAL:
Note: The CHTVW vaporizer should be mounted so that the con-
trol box does not fall in direct sunlight.
The bed plate should be mounted on solid foundation, prefer-
ably level.
The pipe lines from the Chromalox vaporizer to the process
should be the same size as the vaporizer’s piping connections. All
piping should be arranged so that the vaporizer is not subject to
extreme nozzle loading due to thermal expansion and contraction of
pipe lines. If these instructions are not followed, cracks could devel-
op in the vaporizer where the inlet and outlet nozzles are attached.
1. The piping of the entire system should be arranged to minimize
pockets where air may be trapped. Manual air vents or bleeder
valves should be provided at all high points in the system and
every time the flow of the condensate has to drop.
2. Condensate return systems:
A. Gravity return type: The simplest and most easily operat-
ed type of vaporizer is one in which the condensate from the
heating equipment is returned to the vaporizer by gravity,
thus providing a system without moving parts. Such a sys-
tem is possible if there is sufficient difference in elevation
between the process and the vaporizer so the static liquid
head will counter-balance all frictional losses in the vapor-
izer, vapor piping process and condensate return piping
without flooding the heated equipment. See Figure 1 for a
typical schematic piping diagram.
B. Pumped return type: Where there is insufficient differ-
ence in elevation between the vaporizer and the process, the
condensate must be returned to the vaporizer by a pump.
Normally, these pumps are of the centrifugal type; howev-
er, positive displacement pump may also be used. See
Figure 2 for a typical schematic piping diagram.
3. Hartford Loop – In gravity return systems a Hartford Loop
should be incorporated where the condensate is returned to any
point below the desired liquid level of the vaporizer.
A Hartford Loop consists of a line without valves outside of
the vaporizer connecting the vapor outlet and the condensate
inlet. The condensate return line is connected to the vapor-con-
densate line or loop at the same elevation as the lowest permis-
sible level in the vaporizer. Thus, a vacuum in the heated equip-
ment can then pull liquid from the vaporizer (or a closed valve
in the vapor line can force liquid from the vaporizer) only until
the level in the vaporizer falls to the level of this connection.
Also, the resultant liquid hammering will give warning that the
liquid level in the vaporizer is too low. (See Figure 1 below.)
4. Note: All flange connections should be checked and tightened
if necessary. These sometimes loosen during transit.
ELECTRIC:
GENERAL
The Chromalox Horizontal Electric Vaporizer is a thoroughly
engineered pre-tested package, designed to give years of service,
virtually maintenance free if properly installed. The CHTV series
is ASME certified for 150 PSI at 750°F and is available in four
models, each with basic features that comply with the National
Electrical Code. Model CHTV has general-purpose NEMA I con-
struction and can be used where no hazards exist. Model CHTVO
is oil and dust tight as specified by NEMA XII standards. Model
CHTVW can be used where weather-resistant construction is
required and is constructed according to NEMA IV specifications.
Model CHTVX, Class 1, Group D, Division 1 is explosion-resis-
tant and is constructed to operate in hazardous or explosive areas.
WARNING: Vessel and pipe surfaces could achieve temperatures
higher than allowed for Class 1, Group D, Division 1 hazardous
areas. Common to all four models: OCE (open coil element) type
heating elements installed in 3”, schedule 40 seamless carbon steel
pipes; watt density on the outside of the pipe surface is 10 watts
per square inch; elements are removable without draining the fluid
in the vaporizer; requirements 208, 240, 480 and 550 volt, 3 phase,
60 cycle, 15 to 300kW.
INSTALLATION
Heater Terminal
Enclosure
Heater Terminal
Enclosure
Safety
Valve
Jacketed
Vessel
Vapor
Outlet
Hartford
Loop
Jacketed
Vessel
Liquid
Liquid Return
Liquid
Return
Pump
Condensate
Return
Tank
Vapor Outlet
Figure 1 Figure 2
Control Box Size No. Control
kW Volts H L D Circuits Accomplished By
15 240 1 Pressure
Thru or 30 x 24 x 8 1 Control with
30 480 1 Switch
40 240 1 Pressure
Thru or 30 x 30 x 8 2 Control with
60 480 2 Switches
75 240 1 Pressure
Thru or 42 x 30 x 8 3 Control with
100 480 3 Switches
1 Proportional
125 Pressure Control
Thru 480 48 x 36 x 8 4 with 4-step
150 electronic stepper
1 Proportional
175 Pressure Control
Thru 480 60 x 36 x 8 6 with 6-step
300 electronic stepper